Accepted Manuscript Title: Hollow Latex Particles Functionalized with Chitosan for the Removal of Formaldehyde from Indoor Air Author: Sukanya Nuasaen Pakorn Opaprakasit Pramuan Tangboriboonrat PII: DOI: Reference:
S0144-8617(13)00951-X http://dx.doi.org/doi:10.1016/j.carbpol.2013.09.059 CARP 8148
To appear in: Received date: Revised date: Accepted date:
20-7-2013 15-9-2013 18-9-2013
Please cite this article as: Nuasaen, S., Opaprakasit, P., & Tangboriboonrat, P., Hollow Latex Particles Functionalized with Chitosan for the Removal of Formaldehyde from Indoor Air, Carbohydrate Polymers (2013), http://dx.doi.org/10.1016/j.carbpol.2013.09.059 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
1 1
Highlights
2
5 6
demonstrated by FTIR.
ip t
4
The formaldehyde adsorption in HL-chitosan and HL-PEI particles were
The nucleophilic addition of amines to carbonyls generated carbinolamine and Schiff base.
cr
3
The major product appeared in HL-chitosan were carbinolamine.
8
The intensity of carbinolamine and Schiff base increased with formaldehyde
12 13
an
M
efficiency.
d
11
Compared to HL-PEI, HL-chitosan possesses higher formaldehyde adsorption
te
10
exposure times.
Ac ce p
9
us
7
Page 1 of 39
2 13
Hollow Latex Particles Functionalized with Chitosan for the Removal of
14
Formaldehyde from Indoor Air
15
ip t
Sukanya Nuasaena, Pakorn Opaprakasitb, Pramuan Tangboriboonrata*
16 17
a
18
Phyathai, Bangkok 10400, Thailand
19
b
20
Institute of Technology (SIIT), Thammasat University, Pathum Thani 12120, Thailand
21
*Corresponding author: [email protected] (P. Tangboriboonrat)
22
Tel.: +66-2-2015135
23
Fax: +66-2-3547151
24
Author : [email protected] (P. Opaprakasit)
25
Author : [email protected] (S. Nuasaen)
us
cr
Department of Chemistry, Faculty of Science, Mahidol University, Rama 6 Road,
Ac ce p
te
d
M
an
School of Bio-Chemical Engineering and Technology, Sirindhorn International
Page 2 of 39
3 26
Abstract Chitosan and polyethyleneimine (PEI) functionalized hollow latex (HL)
28
particles were conveniently fabricated by coating poly(methyl methacrylate-co-divinyl
29
benzene-co-acrylic acid) (P(MMA/DVB/AA)) HL particles with 5 wt% chitosan or 14
30
wt% PEI. The materials were used as formaldehyde adsorbent, where their
31
adsorbent activity was examined by Fourier Transform Infrared (FTIR) spectroscopy.
32
The nucleophilic addition of amines to carbonyls generated a carbinolamine
33
intermediate with a characteristic band at 1020 cm-1 and Schiff base product at 1650
34
cm-1, whose intensity increased with prolonged formaldehyde exposure times. The
35
major products observed in HL-chitosan were carbinolamine and Schiff base,
36
whereas a small amount of Schiff base was obtained in HL-PEI particles, confirming
37
a chemical bond formation without re-emission of formaldehyde. Compared to HL-
38
PEI, HL-chitosan possesses higher formaldehyde adsorption efficiency. Besides
39
providing opacity and whiteness, the multilayer HL-chitosan particles can effectively
40
remove indoor air pollutants, i.e., formaldehyde gas, and, hence, would be useful in
41
special coating applications.
42
Keywords:
43
Polyethyleneimine
45
cr
us
an
M
d
te
Ac ce p
44
ip t
27
Hollow
latex
particle,
Formaldehyde
adsorption,
Chitosan,
Introduction
46 47
Formaldehyde, a colourless, flammable, and bad smelling gas, is a common
48
precursor in production of more complex materials, e.g., phenol-formaldehyde and
49
urea-formaldehyde resins, which are widely used as wood-binding products and
50
insulating foam (Cogliano et al., 2005). Formaldehyde is also applied in plastics,
Page 3 of 39
4 51
coatings and textile finishing in spite of the fact that it is carcinogenic in humans
52
(Cogliano
53
http://www.epa.gov/teach/chem_summ/ Formaldehyde_ summary.pdf, 2013). When
54
absorbed in the upper respiratory tract, it can be oxidized to formate and carbon
55
dioxide or incorporated into biological macromolecules (Heack et al., 1985). At > 6
56
ppm of formaldehyde, cellular proliferation increases and then amplifies the
57
genotoxic effect (Cogliano et al., 2005). In addition, there is strong but not sufficient
58
evidence that formaldehyde causes leukemia. Therefore, emitted formaldehyde gas
59
in indoor air is considered hazardous and should be removed.
al.,
2005;
Formaldehyde
TEACH
Chemical
Summary,
an
us
cr
ip t
et
Among several methods used in the removal of formaldehyde in an indoor
61
environment, e.g., decomposition using photocatalyst and physical adsorption by
62
porous materials, one of the effective methods is chemical adsorption, where a re-
63
emission is excluded due to strong chemical bonding (Obee & Brown, 1995; Agudo,
64
Polo, Bernal, Coronas & Santamaria, 2004; Wada, Uragami & Matoba, 2005).
65
Formaldehyde gas can be chemically adsorbed by polymeric amines, e.g., chitosan
66
and polyethyleneimine (PEI) via a reaction of primary (1°) amines to form
67
azomethine or Schiff base, a compound containing an aryl or alkyl carbon-nitrogen
68
double bond (Wada et al., 2005; Gesser & Fu,1990; Yang, Liu, Yu & Chen, 2011;
69
Silva et al., 2011). Enhancement of formaldehyde adsorption was achieved by
70
increasing the content of amines in the adsorbent. Nonporous TiO2 fibre
71
functionalized with high PEI content showed high adsorbent efficiency, and was used
72
as quartz crystal microbalance (QCM) sensors (Wang et al., 2012). Chitosan-
73
hybridized acrylic resin was used as a binder in interior finishing coating for
74
formaldehyde adsorption by employing the reaction between amino group of
75
chitosan and carbonyl of formaldehyde (Wada et al., 2005). Most importantly, when
Ac ce p
te
d
M
60
Page 4 of 39
5 76
the Schiff base is formed, adsorbed formaldehyde was not released from chitosan-
77
hybridized acrylic resin film, even with heat treating the film at 60°C for 2 h. For preparation of chitosan-coated particles, colloidal particles having high
79
surface area were used as a substrate to increase the amount of attached chitosan.
80
As a cationic polymer, chitosan is conveniently coated onto oppositely charge
81
colloidal particles, e.g., poly(styrene-co-acrylic acid) (P(St/AA)), via the Layer by
82
Layer (LbL) technique. The thickness of the adsorbed chitosan layer increased when
83
P(St/AA) particles containing a higher amount of carboxylic acid groups on the
84
surface were employed (Du, Liu, Mu & Wang, 2010). Chemical structure also has a
85
strong effect on the coating efficiency. Compared to the high charge density linear
86
poly(allylamine hydrochloride) (PAH), the lower charge density branched PEI formed
87
a thicker layer on silica nanoparticles (Nypelo, Osterberg, Zu & Laine, 2011).
M
an
us
cr
ip t
78
In this study, carboxylated hollow latex (HL) polymer particles or void
89
containing particles have hiding power due to multiple scattering between its
90
surrounding medium and void, were used as a substrate for chitosan or PEI coating
91
(Silva & Galembeck, 2010). The composite material was designed to combine both
92
optical property and formaldehyde adsorption ability. Besides higher surface to
93
volume ratio, the advantages of HL particles over conventional white pigments or
94
opacifying agents are; lower density, better UV resistance, lower coefficient to
95
thermal expansion, less agglomeration, and lower cost per gallon (McDonald &
96
Devon, 2002; Bourgeat-Lami, 2003). Therefore, HL particles possessing high
97
surface charge density and strong double shell are prepared via the template based
98
strategy seeded emulsion polymerization, using P(St/AA) as a seed particle and
99
methyl methacrylate (MMA)/divinyl benzene (DVB)/AA as monomers (Nuasaen &
Ac ce p
te
d
88
Page 5 of 39
6 Tangboriboonrat, 2013). The spherical and non-collapsed HL particles having voids
101
of ca. 280 nm in size are then coated with chitosan or PEI to produce HL-chitosan or
102
HL-PEI particles via the LbL technique. The materials are used as formaldehyde
103
adsorbent. The chemical composition, size, charge and morphology of HL-chitosan
104
and HL-PEI particles are characterized by Fourier Transform Infrared (FTIR)
105
spectroscopy, thermogravimetric analysis, dynamic light scattering, and transmission
106
electron microscopy. Effect of type of polymeric amines on formaldehyde adsorption
107
behaviours and the adsorption mechanism are also analysed by FTIR spectroscopy.
108
2. Experimental
109
2.1 Materials
M
an
us
cr
ip t
100
Styrene (St) (Sigma Aldrich, Purum) and methyl methacrylate (MMA) (Fluka,
111
Purum) were purified by passing through a column packed with neutral and basic
112
aluminum oxide (Fluka, Purum), while acrylic acid (AA) (Aldrich, Purum) was distilled
113
before use. Divinyl benzene (DVB) (Merck, Synthesis), potassium persulfate (KPS)
114
(Fluka, Puriss), and 40% formaldehyde (Carlo Erba, Analysis) were used as
115
received. Polyethyleneimine (PEI), MW of 750,000 g/mole (Aldrich, 50 wt% aqueous
116
solution) was diluted to 2 wt%. Chitosan, MW of 22,000 g/mole (90% deacetylation)
117
(Ta Ming Enterprise Co., Ltd., Thailand) was dissolved in 0.1 M acetic acid (Merck,
118
Analysis). Deionized (DI) water was used throughout the work.
119
2.2 Preparation of seed and HL particles
120
Ac ce p
te
d
110
P(St/AA)
latex
particles
were
synthesized
by
soap-free
emulsion
121
polymerization (Polpanich, Tangboriboonrat & Elaissari, 2005). DI water (90 g) was
122
bubbled with nitrogen for 30 min before adding St (10 g) and AA (1.5 g). The
Page 6 of 39
7 polymerization was started with the addition of KPS solution (0.1 g in 10 g of water)
124
at 70°C. After the reaction completion, the residual monomers, electrolyte and water-
125
soluble oligomers were removed by centrifugation (12,000 rpm, 20 min) and washed
126
thrice with DI water.
127
Highly-charged
HL
particles
were
prepared
via
ip t
123
seeded
emulsion
polymerization, as previously described (Nuasaen & Tangboriboonrat, 2013).
129
P(St/AA) seed latex (0.523 g) was diluted to 36 g in total. After nitrogen purging for
130
30 min and heating to 80°C, DVB (0.9 g) was added, followed by two portions of
131
MMA/AA/KPS (0.95/0.1/0.007 g). The polymerization was carried out for 5 h. The
132
resulting HL was washed thrice with DI.
133
2.3 Preparation and characterization of HL-chitosan and HL-PEI particles
M
an
us
cr
128
The carboxylated HL particles were coated with chitosan and PEI by simply
135
adding 1% w/v chitosan solution at pH 5 or 2% w/v PEI solution (2.0 ml) at pH 7 into
136
0.5% w/v HL (10.0 ml) while shaking (IKA, VIBRAX VXR basic) at room temperature
137
for 12 h. The free chitosan or PEI was removed from HL-chitosan or HL-PEI by
138
centrifugation (5,000 rpm, 15 min) and washed twice with DI water. Their chemical
139
composition, average size, zeta potential, and morphology were, respectively,
140
characterized by using an FTIR spectrometer in the attenuated total reflection mode
141
(ATR-FTIR; Thermo Scientific, iD5), thermogravimetric analysis (TGA; Mettler
142
Toledo, SDTA851), dynamic light scattering (DLS; Zetasizer Malvern, Nano ZS) and
143
transmission electron microscope (TEM; FEI, TECHNAI), operated at an accelerator
144
voltage of 120 kV.
Ac ce p
te
d
134
145
Page 7 of 39
8 146
2.4 Formaldehyde adsorption test The adsorption test was performed in a 500 ml chamber saturated with
148
formaldehyde vapor, generated by heating a 40% formaldehyde solution at 80°C, in
149
the presence of chitosan, PEI, HL-chitosan, or HL-PEI samples previously dried at
150
60°C for 24 h (Gesser & Fu, 1990). In order to ensure the saturation, formaldehyde
151
vapor was filled into the empty chamber at 25°C for 30 min before starting the first
152
test and for 15 min before starting each consecutive test. After formaldehyde
153
adsorption for 0 to 120 min, the samples were characterized by FTIR (FTIR; Perkin
154
Elmer, Spectra GX) and ATR-FTIR (ATR-FTIR; Thermo Scientific, iD5). FTIR
155
spectra of chitosan, HL-chitosan, and HL-PEI samples were collected on a single-
156
reflection diamond/ZnSe ATR accessory, whereas those of PEI were examined in
157
transmission mode by casting each sample on a Ge window.
158
3. Results and Discussion
159
3.1 Analysis of amine functionalized HL particles
161
cr
us
an
M
d
te
Ac ce p
160
ip t
147
FTIR spectra of PEI, chitosan, HL, HL-PEI, and HL-chitosan are shown in
Fig.1.
162
Page 8 of 39
9 163 164
Figure 1 FTIR spectra of PEI (A), chitosan (B), HL (C), HL-PEI (D) and HLchitosan (E) The characteristic peaks at 3440 and 1558 cm-1 in Spectrum 1A correspond to
166
N-H stretching and N-H vibration of PEI (Jenjob, Tharawut & Sunintaboon, 2012).
167
Spectrum 1B illustrates the characteristic bands at 3440 cm-1, relating to O-H and N-
168
H stretching, whereas two bands at 1650 and 1558 cm-1 are attributed to C=O of
169
amide I and N-H of amide II (He et al., 2012). The existence of PMMA, PAA, PS, and
170
PDVB in HL particles are confirmed by the C=O stretching band at 1731cm-1, C=C-H
171
stretching at 3025 cm-1, and C=C stretching at 1600, 1493, and 1453 cm-1, as shown
172
in Spectrum 1C (Nuasaen & Tangboriboonrat, 2013). A broad band at 1731 cm-1
173
indicates an overlap of two carbonyl groups of PMMA (1731cm-1) and PAA (1705 cm-
174
1
175
All mentioned characteristic bands are observed in Spectra 1D and 1E of HL-PEI
176
and HL-chitosan, respectively. Additionally, the N-H bending mode, appeared at
177
1558 cm-1, confirms the presence of amine groups in both types of amine-
178
functionalized HL particles.
cr
us
an
M
te
d
) (Hu & Wang, 2012; Canche-Escamilla, Pacheco-Catalan & Andrade-Canto, 2006).
Ac ce p
179
ip t
165
The particle size distribution curves of HL, HL-chitosan, and HL-PEI particles,
180
measured by the DLS technique, are displayed in Fig.2A. The presence of chitosan
181
and PEI as the outermost layer of particles was confirmed by measuring their zeta
182
potentials at various pHs, and the data are shown in Fig.2B. The morphologies of
183
HL, HL-chitosan and HL-PEI particles investigated under TEM are, respectively,
184
presented in Fig.2C-E.
185
Page 9 of 39
M
an
us
cr
ip t
10
186
Figure 2 Particle size (A) and zeta potential (B) of HL, HL-chitosan, and HL-PEI
188
particles and TEM images of HL (C) HL-chitosan (D), and HL-PEI (E)
te
d
187
The larger hydrodynamic volume of HL-chitosan (665 nm) and HL-PEI
190
particles (655 nm), compared to that of HL (530 nm), indicates the presence of
191
chitosan and PEI on HL particles. Although the molecular weight (MW) of chitosan
192
(22,000 g/mole) is much lower than that of PEI (750,000 g/mole), the average sizes
193
of HL-chitosan and HL-PEI are not much different. This might be because the trains
194
of chitosan molecules, having high Tg of 200°C, are too rigid to lie orderly and
195
closely on the HL surface, while the free loops and tails of chitosan segments are
196
extended away from the surface into aqueous medium (Guo & Gemeinhart, 2008).
197
On the contrary, all parts of the highly-flexible branched PEI (liquid at room
198
temperature) can tightly attach onto the HL particle surface. Moreover, chitosan is
199
fully protonated, but PEI is partially protonated while coated on HL particles at pH 5
Ac ce p
189
Page 10 of 39
11 and 7, respectively (Rinaudo, 2008; Trybala, Szyk-Warszynska & Warszynski, 2009).
201
Since the secondary (2°) and tertiary (3°) amines of PEI have pKa of 6.7 and 11.6,
202
the higher repulsion between positively-charged chitosan molecules would obstruct
203
the uniform coating of chitosan on HL particles.
ip t
200
In Fig.2B, the zeta potentials of HL are negative at pH 6–12, as a result of the
205
dissociation of AA monomer to form COO- groups. The decrease of absolute values
206
from -40.5 mV at pH 6 (COOH, pKa ~4.75) to -26.2 mV at pH 2 is due to the
207
protonation of COO- of AA (Nuasaen & Tangboriboonrat, 2013). After coating the
208
carboxylated HL with chitosan or PEI, both HL-chitosan and HL-PEI particles
209
possess positive zeta potentials at pH 2-8 and at pH 2-10, because of the
210
protonation of these polymeric amines. Since the branched PEI, composed of 1°, 2°
211
and 3° amines, carries positive charges even in acidic or mild basic environments,
212
the positive charge of HL-PEI at higher pH compared to HL-chitosan is attributed to
213
the protonation of 3° amine (Demadis, Paspalaki & Theodorou, 2011; Peng, Thio &
214
Gerhardt, 2010).
us
an
M
d
te
Ac ce p
215
cr
204
TEM micrographs in Fig.2C-E reveal spherical particles with rough surfaces in
216
all cases. Their average void size is nearly constant at ca. 280 nm, where the
217
particles average diameter increases from 460 nm for HL to ca. 500 nm for the
218
coated HL. The larger particle size confirms the existence of chitosan and PEI on
219
HL-chitosan and HL-PEI surfaces.
220
The weight compositions of chitosan and PEI coated on HL particles were
221
determined from TGA and DTG thermograms of HL, HL-chitosan and HL-PEI
222
(supplementary data, Fig.S1) and the data are summarized in Table 1.
Page 11 of 39
12 223
Table 1 Weight compositions, determined from TGA, of HL, HL-chitosan, and HL-
224
PEI particles Sample
Weight composition (%) at Tdecomposition
Weight (%) of
-
86.5
8.3
HL-chitosan
-
4.5
77.4
12.9
12.7
-
72.5
6.1
HL-PEI
4.8
13.9
an
225
-
cr
-
us
HL
ip t
250 290 445-455 non-decomposed fraction chitosan or PEI in HL
A major weight loss step observed between 360 and 540 °C of all
227
thermograms is due to the decomposition of P(St/AA) and P(MMA/DVB/AA) matrix of
228
HL particles. The important information on the nature of the coating species was
229
obtained at a lower temperature range (200 to 340°C), in which those due to PEI and
230
chitosan occurred at 250 and 290 °C, respectively (Jenjob, 2012; Wazed Ali,
231
Rajendran & Joshi, 2011). The weight contents of chitosan and PEI on HL-chitosan
232
and HL-PEI, calculated from TGA thermograms, are ca. 5 and 14 %, respectively
233
(Table 1). The lower amount of coated chitosan layer on HL particles is likely due to
234
its lower MW, higher rigidity, and full protonation, as earlier stated (Rinaudo, 2008;
235
Jeng, Dai, Chiu & Young, 2007; Kaewsaneha, Opaprakasit, Polpanich, Smanmoo &
236
Tangboriboonrat, 2012). In contrast, high MW and flexible branched PEI was
237
partially protonated at pH 7 and, hence, the electrostatically repulsion among their
238
positive charges is lower than that of chitosan, leading to a higher amount of
239
adsorbed PEI (Trybala et al., 2009).
Ac ce p
te
d
M
226
240
Page 12 of 39
13 241
3.2 Formaldehyde adsorption In formaldehyde adsorption experiments, chitosan, PEI, HL-chitosan, and HL-
243
PEI samples were exposed to saturated formaldehyde vapor for 0, 5, 15, 30, 45, 60,
244
75, 90, and 120 min. The formaldehyde adsorption characteristics of each sample,
245
as a function of adsorption time, were then examined by FTIR spectroscopy.
cr
ip t
242
3.2.1 Formaldehyde adsorption of chitosan and HL-chitosan
247
Formaldehyde adsorption mechanisms of chitosan are examined by FTIR
248
spectra as a function of adsorption times, as shown in Fig. 3 (Spectra B-J). The
249
reaction of chitosan and formaldehyde is proposed in Fig.3K.
250
Ac ce p
te
d
M
an
us
246
251
Figure 3 FTIR spectra of chitosan after formaldehyde adsorption at 0 (B), 5(C),
252
15(D), 30(E), 45(F), 60(G), 75(H), 90(I), and 120 min (J), and a different spectrum of
253
chitosan at 120 min adsorption time after subtraction of neat chitosan (A) and
254
reaction between chitosan and formaldehyde (K)
Page 13 of 39
14 Changes on all characteristic bands at 3440 (O-H and N-H stretching), 1650
256
(C=O of amide I) and 1558 cm-1 (N-H of amide II) of chitosan, after formaldehyde
257
adsorption (Spectra 3C-J), are similar to those of neat chitosan (Spectrum 3B) (He et
258
al., 2012). However, the intensity of the 1020 cm-1 band increases with increasing
259
formaldehyde adsorption time, due to the chemical reaction of chitosan and
260
formaldehyde. To recognize the change of chitosan, a different FTIR spectrum after
261
a subtraction of neat chitosan from the formaldehyde-adsorbed chitosan at 120 min
262
was generated, as displayed in Spectrum 3A. The appearance of a negative band at
263
1558 cm-1 (–NH bending of amide II) and a positive band at 1650 cm-1 (-C=N of
264
azomethine or Schiff base) indicate a nucleophilic addition of amines of chitosan to
265
carbonyl of formaldehyde, followed by an elimination of water (H2O), as proposed in
266
Fig.3K (Knaul, Hudson & Creber, 1999; Zhu, Li, Zheng, Xu & Li, 2012). It is noted
267
that the characteristic band of amide bonds in chitin (amide I) and that of the Schiff
268
base are both located near 1650 cm-1 (Spectra 3A –J)
269
absorption band can also indicate carbonyl group of N-acyl chitosan, occurred from
270
the reaction between chitosan and acid anhydride (Muzzarelli, 1977).
cr
us
an
M
d
te
(He et al., 2012). This
Ac ce p
271
ip t
255
In addition, a sharp positive different band at 1020 cm-1 (aliphatic C-N),
272
corresponding to carbinolamine intermediate, was also observed (Spectrum 3A)
273
(Farris, Song & Huang, 2010; Nishat, Khan, Rasool & Parveen, 2011). This was
274
possibly because the reaction between chitosan and formaldehyde generated not
275
only the Schiff base, but also other intermediate products, which are then
276
transformed to Schiff base structure by dehydration (Fig.3K). However, the high
277
stability of these five-membered ring intermediates, due to intra-molecular H-bonding
278
of carbinolamine, might retard their transformation. In general, the high efficiency of
279
Schiff base formation was achieved by using highly electrophilic carbonyl
Page 14 of 39
15 compounds and strong nucleophilic amines in the absence of electronic and steric
281
factors (Chakraborti, Bhagat & Rudrawar, 2004). Since the free lone pair electrons of
282
N atom of carbinolamine are engaged in the H-bonded structure, the nucleophilicity
283
of amine groups decreases. In the absence of acid protonation, the reaction involved
284
a bad hydroxyl (-OH) leaving group. Therefore, the more stable intermediates,
285
indicated by the 1020 cm-1 band, occurs at high yields compared to the Schiff base
286
structure at 1650 cm-1, as the dehydration of carbinolamine at neutral pH was the
287
rate determination step (Brown, 1999). This was reflected in the different FTIR
288
spectra of the adsorbed samples at various times after subtraction of neat chitosan,
289
as shown in Fig.4 (Spectra A-E).
Ac ce p
te
d
M
an
us
cr
ip t
280
290
Page 15 of 39
16 Figure 4 FTIR different spectra of formaldehyde-adsorbed chitosan at various
292
adsorption times: 5(A), 30(B), 60(C), 90(D) and 120 min (E) and FTIR different
293
spectra of heat-treated samples after subtraction of formaldehyde-adsorbed chitosan
294
at various adsorption times: 5(F), 30(G), 60(H), 90(I), 120 min (J)
ip t
291
It was also found that the amounts of intermediate (1020 cm-1 band) increase
296
with an increase of adsorption time from 5 to 90 min, and remained constant,
297
reflecting a complete consumption of the chitosan amines (Spectra 4A-E). As
298
mentioned above, the reaction proceeded in excellent yields within a short time
299
period (Chakraborti et al., 2004). The negative different patterns at 1070 and 1040
300
cm-1 indicate the conversion of chitosan amines.
an
us
cr
295
In order to prove the transformation of intermediates to Schiff base, the
302
formaldehyde adsorbed chitosan samples at various adsorption times were heated in
303
a vacuum oven at 50°C for 120 min to facilitate the dehydration, and their FTIR
304
spectra were re-examined. The different spectra generated from the subtraction of
305
formaldehyde adsorbed chitosan at various times from those of the vacuum-heat
306
treatment are shown in Fig.4 (Spectra F-J). The absence of the positive different
307
band at 1020 cm-1 reflects the transformation of carbinolamine intermediate to Schiff
308
base structure by a removal of H2O. The appearances of positive band at 1650 cm-1
309
and the negative patterns at 1070 and 1040 cm-1 indicate the conversion of amines
310
to Schiff base structure.
Ac ce p
te
d
M
301
311
FTIR spectra of HL and HL-chitosan at various formaldehyde adsorption times
312
were examined (presented as supplementary data, Fig.S2). The variation of
313
characteristic bands of HL-chitosan, i.e., C=O stretching at 1731 cm-1, C=C
314
stretching at 1600, 1493, and 1453 cm-1 and a shoulder peak of N-H bending at
Page 16 of 39
17 1558 cm-1 at all formaldehyde adsorption times cannot be clearly observed.
316
However, the intensity of the 1020 cm-1 band decreases after coating with chitosan.
317
When HL-chitosan was subjected to formaldehyde adsorption, the band intensity at
318
1020 cm-1 slowly increases with increasing the adsorption time from 0 to 120 min.
320
To explain these results, the spectra of HL-chitosan at various adsorption times were subtracted by that of the original HL, as shown in Fig.5 (Spectra A-E).
cr
319
ip t
315
322
Ac ce p
te
d
M
an
us
321
323
Figure 5 The different spectra of HL-chitosan at various adsorption times: 0 (A),
324
5(B), 45(C), 90(D), and 120(E), after subtraction of HL, and the different spectra of
325
HL-chitosan with a vacuum heat treatment at 0(F), 5(G), 45(H), 90(I), and 120 min
326
(J), after subtraction of HL
Page 17 of 39
18 The different FTIR spectra at 0 and 5 min (Spectra 5A and B) display an
328
intense negative pattern at 1020 cm-1. The negative intensity largely decreases when
329
the adsorption time was prolonged from 5 to 120 min (Spectra 5B-E). Meanwhile, a
330
positive different mode presenting as a broad band centered near 1600 cm-1
331
represents the Schiff base formation (Spectra 5B-E). The results agree well with the
332
uptake of formaldehyde by chitosan particles, i.e., the absorption peak of Schiff base
333
slightly shifts to lower wavenumber (Zhou et al., 2013).The positive pattern increases
334
in intensity with increasing adsorption time, likely a result from the increase in
335
carbinolamine and Schiff base contents, as a function of reaction time with
336
formaldehyde.
an
us
cr
ip t
327
Similar to the experiments on chitosan, HL-chitosan samples after
338
formaldehyde adsorption were also heat treated at 50°C under vacuum. FTIR
339
spectra of HL-chitosan particles at various formaldehyde adsorption times are
340
presented as supplementary data, Fig.S3. The different spectra obtained from
341
subtraction of the heat-treated HL-chitosan by HL, as shown in Fig.5 (Spectra 5F-J),
342
obviously indicate that the intensity of Schiff base band at 1650 cm-1 increases,
343
compared to that obtained at the same adsorption time, before the heat treatment
344
(Spectra 5A-E). The negative different band at 1020 cm-1, however, shows a nearly
345
constant intensity, regardless of adsorption time (Spectra 5F-J). This suggests that
346
most of carbinolamine intermediate species, generated from the reaction of
347
formaldehyde and chitosan on HL-chitosan particles, at any adsorption time, are
348
converted to Schiff base by dehydration. The results are in good agreement with the
349
chitosan model.
Ac ce p
te
d
M
337
350
Page 18 of 39
19 3.2.2 Formaldehyde adsorption of PEI and HL-PEI
352
FTIR spectra of PEI at various formaldehyde adsorption times and a different
353
spectrum of PEI at 120 min after subtraction of neat PEI are presented in Fig.6
354
(Spectra A-J). The reaction of PEI and formaldehyde are proposed in Fig.6K.
ip t
351
356
Ac ce p
te
d
M
an
us
cr
355
357
Figure 6 FTIR spectra of PEI at various formaldehyde adsorption times: 0 (B), 5(C),
358
15(D), 30(E), 45(F), 60(G), 75(H), 90(I), and 120 min (J), and the different spectrum
359
of PEI at 120 min after subtraction of neat PEI (A) and reaction between PEI and
360
formaldehyde (K)
361
Spectra 6B-J show that the intensities of the 1558 and 1471 cm-1 modes,
362
corresponding to –NH bending of 1° amine and –N+H of 1°or 2° amines, decrease
Page 19 of 39
20 363
with increasing formaldehyde adsorption time. This indicates a reaction of 1° and 2°
364
amines with formaldehyde (Gesser & Fu, 1990). Unlike chitosan, the different FTIR spectrum derived from PEI at 120 min
366
adsorption time reveals a positive Schiff base band at 1650 cm-1, whereas a
367
negative pattern of the intermediate structure at 1020 cm-1 is not clearly observed, as
368
shown in Spectrum 6A. The corresponding different spectra of PEI at all adsorption
369
times show similar characteristics (Supplementary data, Fig.S4). The intensity of the
370
positive different band of the Schiff base at 1650 cm-1 increases with increasing
371
adsorption time, whereas the band intensities of the 1558 and 1471 cm-1 modes,
372
corresponding to –NH bending of 1° amine and –N+H of 1°or 2° amines, decreases.
373
This suggests that the formation of Schiff bases via nucleophilic addition of 1° and 2°
374
amines of branched PEI to the carbonyl group of formaldehyde followed by
375
dehydration is preferable, compared to chitosan, due to its low degree of intra-
376
molecular H-bonding as illustrated in Fig.6K (Chakraborti et al., 2004).
te
d
M
an
us
cr
ip t
365
For HL-PEI, the variation in the characteristic band of C=O stretching at 1731
378
cm-1, C=C stretching at 1600, 1493, and 1453 cm-1, and N-H bending at 1558 cm-1
379
after formaldehyde adsorption at various times from 0 to 120 min is not clearly
380
detected in Fig.7 (Spectra A-I). The corresponding FTIR different spectra are shown
381
in Spectra J-N, where a positive pattern attributed to the formation of Schiff base at
382
1650 cm-1, is observed as a shoulder band.
Ac ce p
377
Page 20 of 39
an
us
cr
ip t
21
383
Figure 7 FTIR spectra of HL-PEI at various adsorption times: 120 (A), 90(B), 75(C),
385
60(D), 45(E), 30(F), 15 (G), and 0 min (H) and HL (I), their different spectra at
386
120(J), 90(K), 60(L), 5(M), and 0 min (N), after subtraction of HL
te
d
M
384
The low positive intensity of the intermediate characteristic at 1020 cm-1 is
388
also noticed. In contrast to that of neat PEI model, the characteristic bands of the
389
Schiff base product are not clearly observed in HL-PEI. This is possibly due to a
390
small amount of 1° amine presented in branched PEI (35, 37 and 28% wt for 1°, 2°
391
and 3° amines, respectively), and low reactivity of its 2° amines caused from steric
392
effect (Gesser & Fu, 1990). However, a decrease in intensity of a positive different
393
band of N-H bending mode (1558 cm-1) with time from 0 to 120 min in Spectra 7J-N
394
confirms the progress of reaction between PEI on HL-PEI surface with
395
formaldehyde.
Ac ce p
387
396
Page 21 of 39
22 397
Conclusions HL-chitosan and HL-PEI particles, prepared by the seeded emulsion
399
polymerization and the LbL technique, can chemically adsorb formaldehyde via the
400
nucleophilic addition of amines to carbonyls of formaldehyde, followed by the
401
elimination of water molecules. FTIR spectra reveal that the two species, i.e.,
402
carbinolamine intermediate and Schiff base, are generated when HL-chitosan is
403
used in formaldehyde adsorption tests, whereas, the Schiff base structure is not
404
clearly observed in HL-PEI. In both cases, the adsorbent activity increases with
405
increasing formaldehyde adsorption time. The transformation of intermediate to
406
Schiff base can be accelerated by increase of temperature. Further modifications of
407
multilayer HL-chitosan particles could lead to a special indoor coating material.
408
Acknowledgements
cr
us
M
an
grant
d
Research
(RTA5480007)
from
The
Thailand
Research
Fund
te
409
ip t
398
(TRF)/Commission on Higher Education to P.T. and a scholarship from TRF through
411
the Royal Golden Jubilee Ph.D. Program (Grant No. PHD/0190/2553) to S.N. are
412
gratefully acknowledged.
413
Ac ce p
410
Page 22 of 39
23 413 414
References Agudo, S., Polo, A.C., Bernal, M.P., Coronas, J., & Santamaria, J. (2004). Removal of Pollutants from Indoor Air using Zeolite Membranes.
416
Membrane Science, 240, 159-166.
418
Applications.
419
Characterization. (pp.189-223). Marcel Dekker.
421
Elaissari,
A.
(Eds),
Colloidal
Polymers:
Synthesis
and
Brown, K. H. (1999). Kinetic studies on the reaction of formaldehyde with
an
420
In
cr
Bourgeat-Lami, E. (2003). Hollow Particle Synthetic Pathways and Potential
us
417
Journal of
ip t
415
amines in the presence of sulfite, Durham theses, Durham University. Canche-Escamilla, G., Pacheco-Catalan, D.E., & Andrade-Canto, S.B. (2006).
423
Modification of Properties of Rayon Fibre by Graft Copolymerization with Acrylic
424
Monomer. Journal of Materials Science, 41, 7296-7301.
d
M
422
Chakraborti, A.K., Bhagat, S., & Rudrawar, S. (2004). Magnesium perchlorate
426
as an efficient catalyst for the synthesis of imines and phenylhydrazones.
427
Tetrahedron Letter, 45, 7641-7644.
Ac ce p
428
te
425
Cogliano, V.J., Grosse, Y., Baan, R.A., Straif, K., Secretan, M.B., & El
429
Ghissassi, F. and the work group for volume 88. (2005). Meeting Report: Summary
430
of IARC Monographs on Formaldehyde, 2-Butoxyethanol, and 1-tert-Butoxy-2-
431
Propanol. Environmental Health Perspectives, 113, 1205-1208.
432
Da Silva, C.M., Da Silva, D.L., Modolo, L.V., Alves, R.B., de Resende, M.A.,
433
Martins, C.V.B., & De Fatima, A. (2011). Schiff bases: A Short Review of Their
434
Antimicrobial Activities. Journal of Advanced Research, 2, 1-8.
Page 23 of 39
24 435
Demadis, K.D., Paspalaki, M., & Theodorou, J. (2011). Controlled Release of
436
Bis(phosphonate) Pharmaceuticals from Cationic Biodegradable Polymeric Matrices.
437
Industrial & Engineering Chemistry Research, 50, 5873-5876. Du, P., Liu, P., Mu, B., & Wang, Y. (2010). Monodisperse Superparamagnetic
439
pH-Sensitive Single-Layer Chitosan Hollow Microsphere with Controllable Structure.
440
Journal of Polymer Science: Part A: Polymer Chemistry, 48, 4981-4988.
cr
ip t
438
Farris, S., Song, J., & Huang, Q. (2010). Alternative Reaction Mechanism for
442
the Cross-Linking of Gelatin with Glutaraldehyde. Journal of Agricultural and Food
443
Chemistry, 58, 998-103.
an
Formaldehyde TEACH Chemical Summary, US Environmental Protection
445
Agency.
446
Accessed on June, 2013.
449
d
Gesser, H.D., & Fu, S. (1990).
te
448
http://www.epa.gov/teach/chem_summ/Formaldehyde_summary.pdf.
Removal of Aldehydes and Acidic Pollutants
from Indoor Air. Environmental Science & Technology, 24, 495-497.
Ac ce p
447
M
444
us
441
Guo, C., & Gemeinhart, R.A. (2008). Understanding the Adsorption
450
Mechanism of Chitosan onto Poly(lactide-co-glycolide) Particles. European Journal
451
of Pharmaceutics and Biopharmaceutics, 70, 597-604.
452
Heack, Hd’A., Casanova-Schmitz, M., Dodd, P.B., Schachter, E.N., Witek,
453
T.J., & Tosun, T. (1985). Formaldehyde (CH2O) Concentration in the Blood of
454
Humans and Fischer-344 Rats Exposed to CH2O under Controlled Conditions.
455
American Industrial Hygiene Association Journal, 46, 1-3.
Page 24 of 39
25 456
He, G., Wang, Z., Zheng, H., Yin, Y., Xiong, X., & Lin, R. (2012). Preparation,
457
Characterization and Properties of Aminoethyl Chitin Hydrogels.
458
Polymers, 90, 1614-1619.
461
ip t
460
Hu, H., Wang, H., & Du, Q. (2012). Preparation of pH-Sensitive Polyacrylic Acid Hollow Microspheres and Their Release Properties. Soft Matter, 8, 2816-2822.
cr
459
Jeng, J., Dai, C.A., Chiu, W.Y., & Young, P.Y. (2007). Effect of Cationic
462
Surfactant
463
Miniemulsion Modified by Chitosan. Polymer International, 56, 746-753.
Homogenization
and
Polymerization
of
Methyl
us
on
an
464
Methacrylate
Jenjob, S., Tharawut, T., & Sunintaboon, P. (2012). Facile Synthesis of Silver
465
Immobilized-Poly(methyl
466
Composite. Materials Science and Engineering C, 32, 2068-2072.
Core-Shell
Particle
M
methacrylate)/Polyethyleneimine
Kaewsaneha, C., Opaprakasit, P., Polpanich, D., Smanmoo, S., &
d
467
Carbohydrate
468
Tangboriboonrat, P. (2012).
469
Magnetic Polymeric Nanoparticle using Chitosan as Spacer. Journal of Colloid and
470
Interface Science, 377, 145-152.
te
Ac ce p
471
Immobilization of Fluorescein Isothiocyanate on
Knaul, O.Z.,
Hudson, S. M., &
Creber, K.A. M. (1999). Crosslinking of
472
Chitosan Fibers with Dialdehydes: Proposal of a New Reaction Mechanism. Journal
473
of Polymer Science: Part B: Polymer Physics, 37, 1079-1094.
474 475 476
Mc Donald, C.J., & Devon, M. J. (2002). Hollow Latex Particles: Synthesis
and Applications. Advances in Colloid and Interface Science, 99, 181-213. Muzzarelli, R.A.A. (1977). Chitin. Oxford: Pergamon Press, (pp.132).
Page 25 of 39
26 Nishat, N., Khan, S.A., Rasool, R., & Parveen, S. (2011). Synthesis, Spectral
478
Characterization and Biocidal Activity of Thermally Stable Polymeric Schiff Base and
479
Its Polymer Metal Complexes. Journal of Inorganic and Organometallic Polymers,
480
21, 673-681.
ip t
477
Nuasaen, S., & Tangboriboonrat, P. (2013). Highly Charged Hollow Latex
482
Particles Prepared via Seeded Emulsion Polymerization. Journal of Colloid and
483
Interface Science, 396, 75-82.
us
cr
481
Nypelo, T., Osterberg, M., Zu, X., & Laine, J. (2011). Preparation of Ultrathin
485
Coating Layers Using Surface Modified Silica Nanoparticles. Colloids and Surfaces
486
A: Physicochemical and Engineering Aspects, 392, 313-321.
M
an
484
Obee, T.N., & Brown, R.T. (1995). TiO2 Photocatalysis for Indoor Air
488
Applications: Effects of Humidity and Trace Contaminant Levels on the Oxidation
489
Rates of Formaldehyde, Toluene, and 1, 3-Butadiene. Environmental Science &
490
Technology, 29, 1223-1231.
te
Ac ce p
491
d
487
Peng, C., Thio, Y.S., & Gerhardt, R.A. (2010). Enhancing the Layer-by-Layer
492
Assembly of Indium Tin Oxide Thin Films by Using Polyethyleneimine. Journal of
493
Physical Chemistry C, 114, 9685-9692.
494
Polpanich, D., Tangboriboonrat, P., & Elaissari, A. (2005). The effect of
495
Acrylic Acid Amount on the Colloidal Properties of Polystyrene Latex. Colloid &
496
Polymer Science, 284, 183-191.
497 498
Rinaudo, M. (2008). Main Properties and Current Applications of Some Polysaccharides as Biomaterials. Polymer International, 57, 397-430.
Page 26 of 39
27 499
Silva, C. A., & Galembeck, F. (2010). Void Formation and Opacity in Latex
500
Films with Aluminum Phosphate Particles. Colloids and Surfaces A: Physicochemical
501
and Engineering Aspects, 363, 146-154. Trybala, A., Szyk-Warszynska, L., &
Warszynski, P. (2009).The Effect of
ip t
502 503
Anchoring PEI Layer on the Build-up of Polyelectrolyte Multilayer Films at
504
Homogeneous
505
Physicochemical and Engineering Aspects, 343, 127-132.
Surfaces.
Colloids
and
Surfaces
cr
Heterogeneous
A:
us
and
Wada, T., Uragami, T., & Matoba, Y. (2005). Chitosan-Hybridized Acrylic
507
Resins Prepared in Emulsion Polymerizations and Their Application as Interior
508
Finishing Coating. Journal of Coating Technology and Research, 2, 577-582. Wang, X., Cui, F.,
M
509
an
506
Lin, J., Ding, B., Yu, J., & Al-Deyab, S.S. (2012).
Functionalized Nanoporous TiO2 Fibers on Quartz Crystal Microbalance Platform for
511
Formaldehyde Sensor. Sensors and Actuators B: Chemical, 171-172, 658-665.
te
d
510
Wazed Ali, S., Rajendran, S., & Joshi, M. (2011). Synthesis and
513
Characterization of Chitosan and Silver Loaded Chitosan Nanoparticles for Bioactive
514
Polyester. Carbohydrate Polymers, 83, 438-446.
515
Ac ce p
512
Yang, K., Liu, Y., Yu, C., & Chen, B. (2011). Fabrication of Chitosan/Silver
516
Nanocomposites based on Electrochemical Methods for Removing Formaldehyde in
517
Air. Materials Chemistry and Physics, 126, 993-997.
518
Zhou, X., Cheng, X.J., Liu, W.F., Li, J., Ren, L.H., Dang, Q.F., Feng, C.,
519
Chen, X.G. (2013). Optimization and Characteristics of Preparing Chitosan
520
Microspheres Using Response Surface Methodology. Journal of Applied Polymer
521
Science, 127, 4433-4439.
Page 27 of 39
28 522
Zhu, Y., Li, H., Zheng, Q., Xu, J., & Li, X. (2012). Amine-Functionalized SBA-
523
15 with Uniform Morphology and Well-Defined Mesostructure for Highly Sensitive
524
Chemosensors to Detect Formaldehyde Vapor. Langmuir, 28, 7843-7850.
ip t
525
Ac ce p
te
d
M
an
us
cr
526
Page 28 of 39
29 Table
527
Table 1 Weight compositions, determined from TGA, of HL, HL-chitosan and HL-PEI
528
particles Sample
Weight composition (%) at Tdecomposition
290
445-455 non-decomposed fraction
HL
-
-
86.5
8.3
HL-chitosan
-
4.5
77.4
12.9
12.7
-
72.5
6.1
4.8 13.9
M
529
an
HL
chitosan or PEI in
us
250
HL-PEI
Weight (%)
cr
of
ip t
526
Ac ce p
te
d
530
Page 29 of 39
30 530
Figure Captions
531
Figure 1 FTIR spectra of PEI (A), chitosan (B), HL (C), HL-PEI (D) and HL-chitosan
533
(E)
534
Figure 2 Particle size (A) and zeta potential (B) of HL, HL-chitosan and HL-PEI
535
particles and TEM images of HL (C) HL-chitosan (D) and HL-PEI (E)
536
Figure 3 FTIR spectra of chitosan after formaldehyde adsorption at 0 (B), 5(C),
537
15(D), 30(E), 45(F), 60(G), 75(H), 90(I) and 120 min (J), and a different spectrum of
538
chitosan at 120 min adsorption time after subtraction of neat chitosan (A) and
539
reaction between chitosan and formaldehyde (K)
540
Figure 4 FTIR different spectra of formaldehyde-adsorbed chitosan
541
adsorption times: 5(A), 30(B), 60(C), 90(D) and 120 min (E) and FTIR different
542
spectra of heat-treated samples after subtraction of formaldehyde-adsorbed chitosan
543
at various adsorption times: 5(F), 30(G), 60(H), 90(I), 120 min (J)
544
Figure 5 The different spectra of HL-chitosan at various adsorption times: 0 (A),
545
5(B), 45(C), 90(D), and 120(E), after subtraction of HL, and the different spectra of
546
HL-chitosan with a vacuum heat treatment at 0(F), 5(G), 45(H), 90(I) and 120 min
547
(J), after subtraction of HL
548
Figure 6 FTIR spectra of PEI at various formaldehyde adsorption times: 0 (B), 5(C),
549
15(D), 30(E), 45(F), 60(G), 75(H), 90(I) and 120 min (J), and the different spectrum
550
of PEI at 120 min after subtraction of neat PEI (A) and reaction between PEI and
551
formaldehyde (K)
at various
Ac ce p
te
d
M
an
us
cr
ip t
532
Page 30 of 39
31 Figure 7 FTIR spectra of HL-PEI at various adsorption times: 120 (A), 90(B), 75(C),
553
60(D), 45(E), 30(F), 15 (G) and 0 min (H) and HL (I), their different spectra at 120(J),
554
90(K), 60(L), 5(M) and 0 min (N), after subtraction of HL
555
Figure S1 TGA and DTG thermograms of HL (A), HL-chitosan (B) and HL-PEI (C)
556
Figure S2 FTIR spectra of HL (A) and HL-chitosan at various formaldehyde
557
adsorption times: 5 (B), 15(C), 30(D), 45(E), 75(F), 90(G), 120 min (H)
558
Figure S3 FTIR spectra of HL(A) and HL-chitosan at various adsorption times with a
559
vacuum heat treatment: 0(B), 5(C), 15(D), 30(E), 45(F), 60(G), 75(H), 90 (I) and 120
560
min(J)
561
Figure S4 FTIR different spectra, at various formaldehyde adsorption times, after
562
subtraction of neat PEI: 120(A), 90(B), 75(C), 60(D), 45(E), 30 (F), 15(G) and 5 min
563
(H)
566 567
cr
us
an
M
d te
565
Ac ce p
564
ip t
552
Page 31 of 39
Ac
ce
pt
ed
M
an
us
cr
i
Figure 1
Page 32 of 39
Ac
ce
pt
ed
M
an
us
cr
i
Figure 2
Page 33 of 39
Ac
ce
pt
ed
M
an
us
cr
i
Figure 3
Page 34 of 39
Ac ce p
te
d
M
an
us
cr
ip t
Figure 4
Page 35 of 39
Ac
ce
pt
ed
M
an
us
cr
i
Figure 5
Page 36 of 39
Ac
ce
pt
ed
M
an
us
cr
i
Figure 6
Page 37 of 39
Ac
ce
pt
ed
M
an
us
cr
i
Figure 7
Page 38 of 39
Ac
ce
pt
ed
M
an
us
cr
i
Graphical Abstract
Page 39 of 39
S0144-8617(13)00951-X http://dx.doi.org/doi:10.1016/j.carbpol.2013.09.059 CARP 8148
To appear in: Received date: Revised date: Accepted date:
20-7-2013 15-9-2013 18-9-2013
Please cite this article as: Nuasaen, S., Opaprakasit, P., & Tangboriboonrat, P., Hollow Latex Particles Functionalized with Chitosan for the Removal of Formaldehyde from Indoor Air, Carbohydrate Polymers (2013), http://dx.doi.org/10.1016/j.carbpol.2013.09.059 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
1 1
Highlights
2
5 6
demonstrated by FTIR.
ip t
4
The formaldehyde adsorption in HL-chitosan and HL-PEI particles were
The nucleophilic addition of amines to carbonyls generated carbinolamine and Schiff base.
cr
3
The major product appeared in HL-chitosan were carbinolamine.
8
The intensity of carbinolamine and Schiff base increased with formaldehyde
12 13
an
M
efficiency.
d
11
Compared to HL-PEI, HL-chitosan possesses higher formaldehyde adsorption
te
10
exposure times.
Ac ce p
9
us
7
Page 1 of 39
2 13
Hollow Latex Particles Functionalized with Chitosan for the Removal of
14
Formaldehyde from Indoor Air
15
ip t
Sukanya Nuasaena, Pakorn Opaprakasitb, Pramuan Tangboriboonrata*
16 17
a
18
Phyathai, Bangkok 10400, Thailand
19
b
20
Institute of Technology (SIIT), Thammasat University, Pathum Thani 12120, Thailand
21
*Corresponding author: [email protected] (P. Tangboriboonrat)
22
Tel.: +66-2-2015135
23
Fax: +66-2-3547151
24
Author : [email protected] (P. Opaprakasit)
25
Author : [email protected] (S. Nuasaen)
us
cr
Department of Chemistry, Faculty of Science, Mahidol University, Rama 6 Road,
Ac ce p
te
d
M
an
School of Bio-Chemical Engineering and Technology, Sirindhorn International
Page 2 of 39
3 26
Abstract Chitosan and polyethyleneimine (PEI) functionalized hollow latex (HL)
28
particles were conveniently fabricated by coating poly(methyl methacrylate-co-divinyl
29
benzene-co-acrylic acid) (P(MMA/DVB/AA)) HL particles with 5 wt% chitosan or 14
30
wt% PEI. The materials were used as formaldehyde adsorbent, where their
31
adsorbent activity was examined by Fourier Transform Infrared (FTIR) spectroscopy.
32
The nucleophilic addition of amines to carbonyls generated a carbinolamine
33
intermediate with a characteristic band at 1020 cm-1 and Schiff base product at 1650
34
cm-1, whose intensity increased with prolonged formaldehyde exposure times. The
35
major products observed in HL-chitosan were carbinolamine and Schiff base,
36
whereas a small amount of Schiff base was obtained in HL-PEI particles, confirming
37
a chemical bond formation without re-emission of formaldehyde. Compared to HL-
38
PEI, HL-chitosan possesses higher formaldehyde adsorption efficiency. Besides
39
providing opacity and whiteness, the multilayer HL-chitosan particles can effectively
40
remove indoor air pollutants, i.e., formaldehyde gas, and, hence, would be useful in
41
special coating applications.
42
Keywords:
43
Polyethyleneimine
45
cr
us
an
M
d
te
Ac ce p
44
ip t
27
Hollow
latex
particle,
Formaldehyde
adsorption,
Chitosan,
Introduction
46 47
Formaldehyde, a colourless, flammable, and bad smelling gas, is a common
48
precursor in production of more complex materials, e.g., phenol-formaldehyde and
49
urea-formaldehyde resins, which are widely used as wood-binding products and
50
insulating foam (Cogliano et al., 2005). Formaldehyde is also applied in plastics,
Page 3 of 39
4 51
coatings and textile finishing in spite of the fact that it is carcinogenic in humans
52
(Cogliano
53
http://www.epa.gov/teach/chem_summ/ Formaldehyde_ summary.pdf, 2013). When
54
absorbed in the upper respiratory tract, it can be oxidized to formate and carbon
55
dioxide or incorporated into biological macromolecules (Heack et al., 1985). At > 6
56
ppm of formaldehyde, cellular proliferation increases and then amplifies the
57
genotoxic effect (Cogliano et al., 2005). In addition, there is strong but not sufficient
58
evidence that formaldehyde causes leukemia. Therefore, emitted formaldehyde gas
59
in indoor air is considered hazardous and should be removed.
al.,
2005;
Formaldehyde
TEACH
Chemical
Summary,
an
us
cr
ip t
et
Among several methods used in the removal of formaldehyde in an indoor
61
environment, e.g., decomposition using photocatalyst and physical adsorption by
62
porous materials, one of the effective methods is chemical adsorption, where a re-
63
emission is excluded due to strong chemical bonding (Obee & Brown, 1995; Agudo,
64
Polo, Bernal, Coronas & Santamaria, 2004; Wada, Uragami & Matoba, 2005).
65
Formaldehyde gas can be chemically adsorbed by polymeric amines, e.g., chitosan
66
and polyethyleneimine (PEI) via a reaction of primary (1°) amines to form
67
azomethine or Schiff base, a compound containing an aryl or alkyl carbon-nitrogen
68
double bond (Wada et al., 2005; Gesser & Fu,1990; Yang, Liu, Yu & Chen, 2011;
69
Silva et al., 2011). Enhancement of formaldehyde adsorption was achieved by
70
increasing the content of amines in the adsorbent. Nonporous TiO2 fibre
71
functionalized with high PEI content showed high adsorbent efficiency, and was used
72
as quartz crystal microbalance (QCM) sensors (Wang et al., 2012). Chitosan-
73
hybridized acrylic resin was used as a binder in interior finishing coating for
74
formaldehyde adsorption by employing the reaction between amino group of
75
chitosan and carbonyl of formaldehyde (Wada et al., 2005). Most importantly, when
Ac ce p
te
d
M
60
Page 4 of 39
5 76
the Schiff base is formed, adsorbed formaldehyde was not released from chitosan-
77
hybridized acrylic resin film, even with heat treating the film at 60°C for 2 h. For preparation of chitosan-coated particles, colloidal particles having high
79
surface area were used as a substrate to increase the amount of attached chitosan.
80
As a cationic polymer, chitosan is conveniently coated onto oppositely charge
81
colloidal particles, e.g., poly(styrene-co-acrylic acid) (P(St/AA)), via the Layer by
82
Layer (LbL) technique. The thickness of the adsorbed chitosan layer increased when
83
P(St/AA) particles containing a higher amount of carboxylic acid groups on the
84
surface were employed (Du, Liu, Mu & Wang, 2010). Chemical structure also has a
85
strong effect on the coating efficiency. Compared to the high charge density linear
86
poly(allylamine hydrochloride) (PAH), the lower charge density branched PEI formed
87
a thicker layer on silica nanoparticles (Nypelo, Osterberg, Zu & Laine, 2011).
M
an
us
cr
ip t
78
In this study, carboxylated hollow latex (HL) polymer particles or void
89
containing particles have hiding power due to multiple scattering between its
90
surrounding medium and void, were used as a substrate for chitosan or PEI coating
91
(Silva & Galembeck, 2010). The composite material was designed to combine both
92
optical property and formaldehyde adsorption ability. Besides higher surface to
93
volume ratio, the advantages of HL particles over conventional white pigments or
94
opacifying agents are; lower density, better UV resistance, lower coefficient to
95
thermal expansion, less agglomeration, and lower cost per gallon (McDonald &
96
Devon, 2002; Bourgeat-Lami, 2003). Therefore, HL particles possessing high
97
surface charge density and strong double shell are prepared via the template based
98
strategy seeded emulsion polymerization, using P(St/AA) as a seed particle and
99
methyl methacrylate (MMA)/divinyl benzene (DVB)/AA as monomers (Nuasaen &
Ac ce p
te
d
88
Page 5 of 39
6 Tangboriboonrat, 2013). The spherical and non-collapsed HL particles having voids
101
of ca. 280 nm in size are then coated with chitosan or PEI to produce HL-chitosan or
102
HL-PEI particles via the LbL technique. The materials are used as formaldehyde
103
adsorbent. The chemical composition, size, charge and morphology of HL-chitosan
104
and HL-PEI particles are characterized by Fourier Transform Infrared (FTIR)
105
spectroscopy, thermogravimetric analysis, dynamic light scattering, and transmission
106
electron microscopy. Effect of type of polymeric amines on formaldehyde adsorption
107
behaviours and the adsorption mechanism are also analysed by FTIR spectroscopy.
108
2. Experimental
109
2.1 Materials
M
an
us
cr
ip t
100
Styrene (St) (Sigma Aldrich, Purum) and methyl methacrylate (MMA) (Fluka,
111
Purum) were purified by passing through a column packed with neutral and basic
112
aluminum oxide (Fluka, Purum), while acrylic acid (AA) (Aldrich, Purum) was distilled
113
before use. Divinyl benzene (DVB) (Merck, Synthesis), potassium persulfate (KPS)
114
(Fluka, Puriss), and 40% formaldehyde (Carlo Erba, Analysis) were used as
115
received. Polyethyleneimine (PEI), MW of 750,000 g/mole (Aldrich, 50 wt% aqueous
116
solution) was diluted to 2 wt%. Chitosan, MW of 22,000 g/mole (90% deacetylation)
117
(Ta Ming Enterprise Co., Ltd., Thailand) was dissolved in 0.1 M acetic acid (Merck,
118
Analysis). Deionized (DI) water was used throughout the work.
119
2.2 Preparation of seed and HL particles
120
Ac ce p
te
d
110
P(St/AA)
latex
particles
were
synthesized
by
soap-free
emulsion
121
polymerization (Polpanich, Tangboriboonrat & Elaissari, 2005). DI water (90 g) was
122
bubbled with nitrogen for 30 min before adding St (10 g) and AA (1.5 g). The
Page 6 of 39
7 polymerization was started with the addition of KPS solution (0.1 g in 10 g of water)
124
at 70°C. After the reaction completion, the residual monomers, electrolyte and water-
125
soluble oligomers were removed by centrifugation (12,000 rpm, 20 min) and washed
126
thrice with DI water.
127
Highly-charged
HL
particles
were
prepared
via
ip t
123
seeded
emulsion
polymerization, as previously described (Nuasaen & Tangboriboonrat, 2013).
129
P(St/AA) seed latex (0.523 g) was diluted to 36 g in total. After nitrogen purging for
130
30 min and heating to 80°C, DVB (0.9 g) was added, followed by two portions of
131
MMA/AA/KPS (0.95/0.1/0.007 g). The polymerization was carried out for 5 h. The
132
resulting HL was washed thrice with DI.
133
2.3 Preparation and characterization of HL-chitosan and HL-PEI particles
M
an
us
cr
128
The carboxylated HL particles were coated with chitosan and PEI by simply
135
adding 1% w/v chitosan solution at pH 5 or 2% w/v PEI solution (2.0 ml) at pH 7 into
136
0.5% w/v HL (10.0 ml) while shaking (IKA, VIBRAX VXR basic) at room temperature
137
for 12 h. The free chitosan or PEI was removed from HL-chitosan or HL-PEI by
138
centrifugation (5,000 rpm, 15 min) and washed twice with DI water. Their chemical
139
composition, average size, zeta potential, and morphology were, respectively,
140
characterized by using an FTIR spectrometer in the attenuated total reflection mode
141
(ATR-FTIR; Thermo Scientific, iD5), thermogravimetric analysis (TGA; Mettler
142
Toledo, SDTA851), dynamic light scattering (DLS; Zetasizer Malvern, Nano ZS) and
143
transmission electron microscope (TEM; FEI, TECHNAI), operated at an accelerator
144
voltage of 120 kV.
Ac ce p
te
d
134
145
Page 7 of 39
8 146
2.4 Formaldehyde adsorption test The adsorption test was performed in a 500 ml chamber saturated with
148
formaldehyde vapor, generated by heating a 40% formaldehyde solution at 80°C, in
149
the presence of chitosan, PEI, HL-chitosan, or HL-PEI samples previously dried at
150
60°C for 24 h (Gesser & Fu, 1990). In order to ensure the saturation, formaldehyde
151
vapor was filled into the empty chamber at 25°C for 30 min before starting the first
152
test and for 15 min before starting each consecutive test. After formaldehyde
153
adsorption for 0 to 120 min, the samples were characterized by FTIR (FTIR; Perkin
154
Elmer, Spectra GX) and ATR-FTIR (ATR-FTIR; Thermo Scientific, iD5). FTIR
155
spectra of chitosan, HL-chitosan, and HL-PEI samples were collected on a single-
156
reflection diamond/ZnSe ATR accessory, whereas those of PEI were examined in
157
transmission mode by casting each sample on a Ge window.
158
3. Results and Discussion
159
3.1 Analysis of amine functionalized HL particles
161
cr
us
an
M
d
te
Ac ce p
160
ip t
147
FTIR spectra of PEI, chitosan, HL, HL-PEI, and HL-chitosan are shown in
Fig.1.
162
Page 8 of 39
9 163 164
Figure 1 FTIR spectra of PEI (A), chitosan (B), HL (C), HL-PEI (D) and HLchitosan (E) The characteristic peaks at 3440 and 1558 cm-1 in Spectrum 1A correspond to
166
N-H stretching and N-H vibration of PEI (Jenjob, Tharawut & Sunintaboon, 2012).
167
Spectrum 1B illustrates the characteristic bands at 3440 cm-1, relating to O-H and N-
168
H stretching, whereas two bands at 1650 and 1558 cm-1 are attributed to C=O of
169
amide I and N-H of amide II (He et al., 2012). The existence of PMMA, PAA, PS, and
170
PDVB in HL particles are confirmed by the C=O stretching band at 1731cm-1, C=C-H
171
stretching at 3025 cm-1, and C=C stretching at 1600, 1493, and 1453 cm-1, as shown
172
in Spectrum 1C (Nuasaen & Tangboriboonrat, 2013). A broad band at 1731 cm-1
173
indicates an overlap of two carbonyl groups of PMMA (1731cm-1) and PAA (1705 cm-
174
1
175
All mentioned characteristic bands are observed in Spectra 1D and 1E of HL-PEI
176
and HL-chitosan, respectively. Additionally, the N-H bending mode, appeared at
177
1558 cm-1, confirms the presence of amine groups in both types of amine-
178
functionalized HL particles.
cr
us
an
M
te
d
) (Hu & Wang, 2012; Canche-Escamilla, Pacheco-Catalan & Andrade-Canto, 2006).
Ac ce p
179
ip t
165
The particle size distribution curves of HL, HL-chitosan, and HL-PEI particles,
180
measured by the DLS technique, are displayed in Fig.2A. The presence of chitosan
181
and PEI as the outermost layer of particles was confirmed by measuring their zeta
182
potentials at various pHs, and the data are shown in Fig.2B. The morphologies of
183
HL, HL-chitosan and HL-PEI particles investigated under TEM are, respectively,
184
presented in Fig.2C-E.
185
Page 9 of 39
M
an
us
cr
ip t
10
186
Figure 2 Particle size (A) and zeta potential (B) of HL, HL-chitosan, and HL-PEI
188
particles and TEM images of HL (C) HL-chitosan (D), and HL-PEI (E)
te
d
187
The larger hydrodynamic volume of HL-chitosan (665 nm) and HL-PEI
190
particles (655 nm), compared to that of HL (530 nm), indicates the presence of
191
chitosan and PEI on HL particles. Although the molecular weight (MW) of chitosan
192
(22,000 g/mole) is much lower than that of PEI (750,000 g/mole), the average sizes
193
of HL-chitosan and HL-PEI are not much different. This might be because the trains
194
of chitosan molecules, having high Tg of 200°C, are too rigid to lie orderly and
195
closely on the HL surface, while the free loops and tails of chitosan segments are
196
extended away from the surface into aqueous medium (Guo & Gemeinhart, 2008).
197
On the contrary, all parts of the highly-flexible branched PEI (liquid at room
198
temperature) can tightly attach onto the HL particle surface. Moreover, chitosan is
199
fully protonated, but PEI is partially protonated while coated on HL particles at pH 5
Ac ce p
189
Page 10 of 39
11 and 7, respectively (Rinaudo, 2008; Trybala, Szyk-Warszynska & Warszynski, 2009).
201
Since the secondary (2°) and tertiary (3°) amines of PEI have pKa of 6.7 and 11.6,
202
the higher repulsion between positively-charged chitosan molecules would obstruct
203
the uniform coating of chitosan on HL particles.
ip t
200
In Fig.2B, the zeta potentials of HL are negative at pH 6–12, as a result of the
205
dissociation of AA monomer to form COO- groups. The decrease of absolute values
206
from -40.5 mV at pH 6 (COOH, pKa ~4.75) to -26.2 mV at pH 2 is due to the
207
protonation of COO- of AA (Nuasaen & Tangboriboonrat, 2013). After coating the
208
carboxylated HL with chitosan or PEI, both HL-chitosan and HL-PEI particles
209
possess positive zeta potentials at pH 2-8 and at pH 2-10, because of the
210
protonation of these polymeric amines. Since the branched PEI, composed of 1°, 2°
211
and 3° amines, carries positive charges even in acidic or mild basic environments,
212
the positive charge of HL-PEI at higher pH compared to HL-chitosan is attributed to
213
the protonation of 3° amine (Demadis, Paspalaki & Theodorou, 2011; Peng, Thio &
214
Gerhardt, 2010).
us
an
M
d
te
Ac ce p
215
cr
204
TEM micrographs in Fig.2C-E reveal spherical particles with rough surfaces in
216
all cases. Their average void size is nearly constant at ca. 280 nm, where the
217
particles average diameter increases from 460 nm for HL to ca. 500 nm for the
218
coated HL. The larger particle size confirms the existence of chitosan and PEI on
219
HL-chitosan and HL-PEI surfaces.
220
The weight compositions of chitosan and PEI coated on HL particles were
221
determined from TGA and DTG thermograms of HL, HL-chitosan and HL-PEI
222
(supplementary data, Fig.S1) and the data are summarized in Table 1.
Page 11 of 39
12 223
Table 1 Weight compositions, determined from TGA, of HL, HL-chitosan, and HL-
224
PEI particles Sample
Weight composition (%) at Tdecomposition
Weight (%) of
-
86.5
8.3
HL-chitosan
-
4.5
77.4
12.9
12.7
-
72.5
6.1
HL-PEI
4.8
13.9
an
225
-
cr
-
us
HL
ip t
250 290 445-455 non-decomposed fraction chitosan or PEI in HL
A major weight loss step observed between 360 and 540 °C of all
227
thermograms is due to the decomposition of P(St/AA) and P(MMA/DVB/AA) matrix of
228
HL particles. The important information on the nature of the coating species was
229
obtained at a lower temperature range (200 to 340°C), in which those due to PEI and
230
chitosan occurred at 250 and 290 °C, respectively (Jenjob, 2012; Wazed Ali,
231
Rajendran & Joshi, 2011). The weight contents of chitosan and PEI on HL-chitosan
232
and HL-PEI, calculated from TGA thermograms, are ca. 5 and 14 %, respectively
233
(Table 1). The lower amount of coated chitosan layer on HL particles is likely due to
234
its lower MW, higher rigidity, and full protonation, as earlier stated (Rinaudo, 2008;
235
Jeng, Dai, Chiu & Young, 2007; Kaewsaneha, Opaprakasit, Polpanich, Smanmoo &
236
Tangboriboonrat, 2012). In contrast, high MW and flexible branched PEI was
237
partially protonated at pH 7 and, hence, the electrostatically repulsion among their
238
positive charges is lower than that of chitosan, leading to a higher amount of
239
adsorbed PEI (Trybala et al., 2009).
Ac ce p
te
d
M
226
240
Page 12 of 39
13 241
3.2 Formaldehyde adsorption In formaldehyde adsorption experiments, chitosan, PEI, HL-chitosan, and HL-
243
PEI samples were exposed to saturated formaldehyde vapor for 0, 5, 15, 30, 45, 60,
244
75, 90, and 120 min. The formaldehyde adsorption characteristics of each sample,
245
as a function of adsorption time, were then examined by FTIR spectroscopy.
cr
ip t
242
3.2.1 Formaldehyde adsorption of chitosan and HL-chitosan
247
Formaldehyde adsorption mechanisms of chitosan are examined by FTIR
248
spectra as a function of adsorption times, as shown in Fig. 3 (Spectra B-J). The
249
reaction of chitosan and formaldehyde is proposed in Fig.3K.
250
Ac ce p
te
d
M
an
us
246
251
Figure 3 FTIR spectra of chitosan after formaldehyde adsorption at 0 (B), 5(C),
252
15(D), 30(E), 45(F), 60(G), 75(H), 90(I), and 120 min (J), and a different spectrum of
253
chitosan at 120 min adsorption time after subtraction of neat chitosan (A) and
254
reaction between chitosan and formaldehyde (K)
Page 13 of 39
14 Changes on all characteristic bands at 3440 (O-H and N-H stretching), 1650
256
(C=O of amide I) and 1558 cm-1 (N-H of amide II) of chitosan, after formaldehyde
257
adsorption (Spectra 3C-J), are similar to those of neat chitosan (Spectrum 3B) (He et
258
al., 2012). However, the intensity of the 1020 cm-1 band increases with increasing
259
formaldehyde adsorption time, due to the chemical reaction of chitosan and
260
formaldehyde. To recognize the change of chitosan, a different FTIR spectrum after
261
a subtraction of neat chitosan from the formaldehyde-adsorbed chitosan at 120 min
262
was generated, as displayed in Spectrum 3A. The appearance of a negative band at
263
1558 cm-1 (–NH bending of amide II) and a positive band at 1650 cm-1 (-C=N of
264
azomethine or Schiff base) indicate a nucleophilic addition of amines of chitosan to
265
carbonyl of formaldehyde, followed by an elimination of water (H2O), as proposed in
266
Fig.3K (Knaul, Hudson & Creber, 1999; Zhu, Li, Zheng, Xu & Li, 2012). It is noted
267
that the characteristic band of amide bonds in chitin (amide I) and that of the Schiff
268
base are both located near 1650 cm-1 (Spectra 3A –J)
269
absorption band can also indicate carbonyl group of N-acyl chitosan, occurred from
270
the reaction between chitosan and acid anhydride (Muzzarelli, 1977).
cr
us
an
M
d
te
(He et al., 2012). This
Ac ce p
271
ip t
255
In addition, a sharp positive different band at 1020 cm-1 (aliphatic C-N),
272
corresponding to carbinolamine intermediate, was also observed (Spectrum 3A)
273
(Farris, Song & Huang, 2010; Nishat, Khan, Rasool & Parveen, 2011). This was
274
possibly because the reaction between chitosan and formaldehyde generated not
275
only the Schiff base, but also other intermediate products, which are then
276
transformed to Schiff base structure by dehydration (Fig.3K). However, the high
277
stability of these five-membered ring intermediates, due to intra-molecular H-bonding
278
of carbinolamine, might retard their transformation. In general, the high efficiency of
279
Schiff base formation was achieved by using highly electrophilic carbonyl
Page 14 of 39
15 compounds and strong nucleophilic amines in the absence of electronic and steric
281
factors (Chakraborti, Bhagat & Rudrawar, 2004). Since the free lone pair electrons of
282
N atom of carbinolamine are engaged in the H-bonded structure, the nucleophilicity
283
of amine groups decreases. In the absence of acid protonation, the reaction involved
284
a bad hydroxyl (-OH) leaving group. Therefore, the more stable intermediates,
285
indicated by the 1020 cm-1 band, occurs at high yields compared to the Schiff base
286
structure at 1650 cm-1, as the dehydration of carbinolamine at neutral pH was the
287
rate determination step (Brown, 1999). This was reflected in the different FTIR
288
spectra of the adsorbed samples at various times after subtraction of neat chitosan,
289
as shown in Fig.4 (Spectra A-E).
Ac ce p
te
d
M
an
us
cr
ip t
280
290
Page 15 of 39
16 Figure 4 FTIR different spectra of formaldehyde-adsorbed chitosan at various
292
adsorption times: 5(A), 30(B), 60(C), 90(D) and 120 min (E) and FTIR different
293
spectra of heat-treated samples after subtraction of formaldehyde-adsorbed chitosan
294
at various adsorption times: 5(F), 30(G), 60(H), 90(I), 120 min (J)
ip t
291
It was also found that the amounts of intermediate (1020 cm-1 band) increase
296
with an increase of adsorption time from 5 to 90 min, and remained constant,
297
reflecting a complete consumption of the chitosan amines (Spectra 4A-E). As
298
mentioned above, the reaction proceeded in excellent yields within a short time
299
period (Chakraborti et al., 2004). The negative different patterns at 1070 and 1040
300
cm-1 indicate the conversion of chitosan amines.
an
us
cr
295
In order to prove the transformation of intermediates to Schiff base, the
302
formaldehyde adsorbed chitosan samples at various adsorption times were heated in
303
a vacuum oven at 50°C for 120 min to facilitate the dehydration, and their FTIR
304
spectra were re-examined. The different spectra generated from the subtraction of
305
formaldehyde adsorbed chitosan at various times from those of the vacuum-heat
306
treatment are shown in Fig.4 (Spectra F-J). The absence of the positive different
307
band at 1020 cm-1 reflects the transformation of carbinolamine intermediate to Schiff
308
base structure by a removal of H2O. The appearances of positive band at 1650 cm-1
309
and the negative patterns at 1070 and 1040 cm-1 indicate the conversion of amines
310
to Schiff base structure.
Ac ce p
te
d
M
301
311
FTIR spectra of HL and HL-chitosan at various formaldehyde adsorption times
312
were examined (presented as supplementary data, Fig.S2). The variation of
313
characteristic bands of HL-chitosan, i.e., C=O stretching at 1731 cm-1, C=C
314
stretching at 1600, 1493, and 1453 cm-1 and a shoulder peak of N-H bending at
Page 16 of 39
17 1558 cm-1 at all formaldehyde adsorption times cannot be clearly observed.
316
However, the intensity of the 1020 cm-1 band decreases after coating with chitosan.
317
When HL-chitosan was subjected to formaldehyde adsorption, the band intensity at
318
1020 cm-1 slowly increases with increasing the adsorption time from 0 to 120 min.
320
To explain these results, the spectra of HL-chitosan at various adsorption times were subtracted by that of the original HL, as shown in Fig.5 (Spectra A-E).
cr
319
ip t
315
322
Ac ce p
te
d
M
an
us
321
323
Figure 5 The different spectra of HL-chitosan at various adsorption times: 0 (A),
324
5(B), 45(C), 90(D), and 120(E), after subtraction of HL, and the different spectra of
325
HL-chitosan with a vacuum heat treatment at 0(F), 5(G), 45(H), 90(I), and 120 min
326
(J), after subtraction of HL
Page 17 of 39
18 The different FTIR spectra at 0 and 5 min (Spectra 5A and B) display an
328
intense negative pattern at 1020 cm-1. The negative intensity largely decreases when
329
the adsorption time was prolonged from 5 to 120 min (Spectra 5B-E). Meanwhile, a
330
positive different mode presenting as a broad band centered near 1600 cm-1
331
represents the Schiff base formation (Spectra 5B-E). The results agree well with the
332
uptake of formaldehyde by chitosan particles, i.e., the absorption peak of Schiff base
333
slightly shifts to lower wavenumber (Zhou et al., 2013).The positive pattern increases
334
in intensity with increasing adsorption time, likely a result from the increase in
335
carbinolamine and Schiff base contents, as a function of reaction time with
336
formaldehyde.
an
us
cr
ip t
327
Similar to the experiments on chitosan, HL-chitosan samples after
338
formaldehyde adsorption were also heat treated at 50°C under vacuum. FTIR
339
spectra of HL-chitosan particles at various formaldehyde adsorption times are
340
presented as supplementary data, Fig.S3. The different spectra obtained from
341
subtraction of the heat-treated HL-chitosan by HL, as shown in Fig.5 (Spectra 5F-J),
342
obviously indicate that the intensity of Schiff base band at 1650 cm-1 increases,
343
compared to that obtained at the same adsorption time, before the heat treatment
344
(Spectra 5A-E). The negative different band at 1020 cm-1, however, shows a nearly
345
constant intensity, regardless of adsorption time (Spectra 5F-J). This suggests that
346
most of carbinolamine intermediate species, generated from the reaction of
347
formaldehyde and chitosan on HL-chitosan particles, at any adsorption time, are
348
converted to Schiff base by dehydration. The results are in good agreement with the
349
chitosan model.
Ac ce p
te
d
M
337
350
Page 18 of 39
19 3.2.2 Formaldehyde adsorption of PEI and HL-PEI
352
FTIR spectra of PEI at various formaldehyde adsorption times and a different
353
spectrum of PEI at 120 min after subtraction of neat PEI are presented in Fig.6
354
(Spectra A-J). The reaction of PEI and formaldehyde are proposed in Fig.6K.
ip t
351
356
Ac ce p
te
d
M
an
us
cr
355
357
Figure 6 FTIR spectra of PEI at various formaldehyde adsorption times: 0 (B), 5(C),
358
15(D), 30(E), 45(F), 60(G), 75(H), 90(I), and 120 min (J), and the different spectrum
359
of PEI at 120 min after subtraction of neat PEI (A) and reaction between PEI and
360
formaldehyde (K)
361
Spectra 6B-J show that the intensities of the 1558 and 1471 cm-1 modes,
362
corresponding to –NH bending of 1° amine and –N+H of 1°or 2° amines, decrease
Page 19 of 39
20 363
with increasing formaldehyde adsorption time. This indicates a reaction of 1° and 2°
364
amines with formaldehyde (Gesser & Fu, 1990). Unlike chitosan, the different FTIR spectrum derived from PEI at 120 min
366
adsorption time reveals a positive Schiff base band at 1650 cm-1, whereas a
367
negative pattern of the intermediate structure at 1020 cm-1 is not clearly observed, as
368
shown in Spectrum 6A. The corresponding different spectra of PEI at all adsorption
369
times show similar characteristics (Supplementary data, Fig.S4). The intensity of the
370
positive different band of the Schiff base at 1650 cm-1 increases with increasing
371
adsorption time, whereas the band intensities of the 1558 and 1471 cm-1 modes,
372
corresponding to –NH bending of 1° amine and –N+H of 1°or 2° amines, decreases.
373
This suggests that the formation of Schiff bases via nucleophilic addition of 1° and 2°
374
amines of branched PEI to the carbonyl group of formaldehyde followed by
375
dehydration is preferable, compared to chitosan, due to its low degree of intra-
376
molecular H-bonding as illustrated in Fig.6K (Chakraborti et al., 2004).
te
d
M
an
us
cr
ip t
365
For HL-PEI, the variation in the characteristic band of C=O stretching at 1731
378
cm-1, C=C stretching at 1600, 1493, and 1453 cm-1, and N-H bending at 1558 cm-1
379
after formaldehyde adsorption at various times from 0 to 120 min is not clearly
380
detected in Fig.7 (Spectra A-I). The corresponding FTIR different spectra are shown
381
in Spectra J-N, where a positive pattern attributed to the formation of Schiff base at
382
1650 cm-1, is observed as a shoulder band.
Ac ce p
377
Page 20 of 39
an
us
cr
ip t
21
383
Figure 7 FTIR spectra of HL-PEI at various adsorption times: 120 (A), 90(B), 75(C),
385
60(D), 45(E), 30(F), 15 (G), and 0 min (H) and HL (I), their different spectra at
386
120(J), 90(K), 60(L), 5(M), and 0 min (N), after subtraction of HL
te
d
M
384
The low positive intensity of the intermediate characteristic at 1020 cm-1 is
388
also noticed. In contrast to that of neat PEI model, the characteristic bands of the
389
Schiff base product are not clearly observed in HL-PEI. This is possibly due to a
390
small amount of 1° amine presented in branched PEI (35, 37 and 28% wt for 1°, 2°
391
and 3° amines, respectively), and low reactivity of its 2° amines caused from steric
392
effect (Gesser & Fu, 1990). However, a decrease in intensity of a positive different
393
band of N-H bending mode (1558 cm-1) with time from 0 to 120 min in Spectra 7J-N
394
confirms the progress of reaction between PEI on HL-PEI surface with
395
formaldehyde.
Ac ce p
387
396
Page 21 of 39
22 397
Conclusions HL-chitosan and HL-PEI particles, prepared by the seeded emulsion
399
polymerization and the LbL technique, can chemically adsorb formaldehyde via the
400
nucleophilic addition of amines to carbonyls of formaldehyde, followed by the
401
elimination of water molecules. FTIR spectra reveal that the two species, i.e.,
402
carbinolamine intermediate and Schiff base, are generated when HL-chitosan is
403
used in formaldehyde adsorption tests, whereas, the Schiff base structure is not
404
clearly observed in HL-PEI. In both cases, the adsorbent activity increases with
405
increasing formaldehyde adsorption time. The transformation of intermediate to
406
Schiff base can be accelerated by increase of temperature. Further modifications of
407
multilayer HL-chitosan particles could lead to a special indoor coating material.
408
Acknowledgements
cr
us
M
an
grant
d
Research
(RTA5480007)
from
The
Thailand
Research
Fund
te
409
ip t
398
(TRF)/Commission on Higher Education to P.T. and a scholarship from TRF through
411
the Royal Golden Jubilee Ph.D. Program (Grant No. PHD/0190/2553) to S.N. are
412
gratefully acknowledged.
413
Ac ce p
410
Page 22 of 39
23 413 414
References Agudo, S., Polo, A.C., Bernal, M.P., Coronas, J., & Santamaria, J. (2004). Removal of Pollutants from Indoor Air using Zeolite Membranes.
416
Membrane Science, 240, 159-166.
418
Applications.
419
Characterization. (pp.189-223). Marcel Dekker.
421
Elaissari,
A.
(Eds),
Colloidal
Polymers:
Synthesis
and
Brown, K. H. (1999). Kinetic studies on the reaction of formaldehyde with
an
420
In
cr
Bourgeat-Lami, E. (2003). Hollow Particle Synthetic Pathways and Potential
us
417
Journal of
ip t
415
amines in the presence of sulfite, Durham theses, Durham University. Canche-Escamilla, G., Pacheco-Catalan, D.E., & Andrade-Canto, S.B. (2006).
423
Modification of Properties of Rayon Fibre by Graft Copolymerization with Acrylic
424
Monomer. Journal of Materials Science, 41, 7296-7301.
d
M
422
Chakraborti, A.K., Bhagat, S., & Rudrawar, S. (2004). Magnesium perchlorate
426
as an efficient catalyst for the synthesis of imines and phenylhydrazones.
427
Tetrahedron Letter, 45, 7641-7644.
Ac ce p
428
te
425
Cogliano, V.J., Grosse, Y., Baan, R.A., Straif, K., Secretan, M.B., & El
429
Ghissassi, F. and the work group for volume 88. (2005). Meeting Report: Summary
430
of IARC Monographs on Formaldehyde, 2-Butoxyethanol, and 1-tert-Butoxy-2-
431
Propanol. Environmental Health Perspectives, 113, 1205-1208.
432
Da Silva, C.M., Da Silva, D.L., Modolo, L.V., Alves, R.B., de Resende, M.A.,
433
Martins, C.V.B., & De Fatima, A. (2011). Schiff bases: A Short Review of Their
434
Antimicrobial Activities. Journal of Advanced Research, 2, 1-8.
Page 23 of 39
24 435
Demadis, K.D., Paspalaki, M., & Theodorou, J. (2011). Controlled Release of
436
Bis(phosphonate) Pharmaceuticals from Cationic Biodegradable Polymeric Matrices.
437
Industrial & Engineering Chemistry Research, 50, 5873-5876. Du, P., Liu, P., Mu, B., & Wang, Y. (2010). Monodisperse Superparamagnetic
439
pH-Sensitive Single-Layer Chitosan Hollow Microsphere with Controllable Structure.
440
Journal of Polymer Science: Part A: Polymer Chemistry, 48, 4981-4988.
cr
ip t
438
Farris, S., Song, J., & Huang, Q. (2010). Alternative Reaction Mechanism for
442
the Cross-Linking of Gelatin with Glutaraldehyde. Journal of Agricultural and Food
443
Chemistry, 58, 998-103.
an
Formaldehyde TEACH Chemical Summary, US Environmental Protection
445
Agency.
446
Accessed on June, 2013.
449
d
Gesser, H.D., & Fu, S. (1990).
te
448
http://www.epa.gov/teach/chem_summ/Formaldehyde_summary.pdf.
Removal of Aldehydes and Acidic Pollutants
from Indoor Air. Environmental Science & Technology, 24, 495-497.
Ac ce p
447
M
444
us
441
Guo, C., & Gemeinhart, R.A. (2008). Understanding the Adsorption
450
Mechanism of Chitosan onto Poly(lactide-co-glycolide) Particles. European Journal
451
of Pharmaceutics and Biopharmaceutics, 70, 597-604.
452
Heack, Hd’A., Casanova-Schmitz, M., Dodd, P.B., Schachter, E.N., Witek,
453
T.J., & Tosun, T. (1985). Formaldehyde (CH2O) Concentration in the Blood of
454
Humans and Fischer-344 Rats Exposed to CH2O under Controlled Conditions.
455
American Industrial Hygiene Association Journal, 46, 1-3.
Page 24 of 39
25 456
He, G., Wang, Z., Zheng, H., Yin, Y., Xiong, X., & Lin, R. (2012). Preparation,
457
Characterization and Properties of Aminoethyl Chitin Hydrogels.
458
Polymers, 90, 1614-1619.
461
ip t
460
Hu, H., Wang, H., & Du, Q. (2012). Preparation of pH-Sensitive Polyacrylic Acid Hollow Microspheres and Their Release Properties. Soft Matter, 8, 2816-2822.
cr
459
Jeng, J., Dai, C.A., Chiu, W.Y., & Young, P.Y. (2007). Effect of Cationic
462
Surfactant
463
Miniemulsion Modified by Chitosan. Polymer International, 56, 746-753.
Homogenization
and
Polymerization
of
Methyl
us
on
an
464
Methacrylate
Jenjob, S., Tharawut, T., & Sunintaboon, P. (2012). Facile Synthesis of Silver
465
Immobilized-Poly(methyl
466
Composite. Materials Science and Engineering C, 32, 2068-2072.
Core-Shell
Particle
M
methacrylate)/Polyethyleneimine
Kaewsaneha, C., Opaprakasit, P., Polpanich, D., Smanmoo, S., &
d
467
Carbohydrate
468
Tangboriboonrat, P. (2012).
469
Magnetic Polymeric Nanoparticle using Chitosan as Spacer. Journal of Colloid and
470
Interface Science, 377, 145-152.
te
Ac ce p
471
Immobilization of Fluorescein Isothiocyanate on
Knaul, O.Z.,
Hudson, S. M., &
Creber, K.A. M. (1999). Crosslinking of
472
Chitosan Fibers with Dialdehydes: Proposal of a New Reaction Mechanism. Journal
473
of Polymer Science: Part B: Polymer Physics, 37, 1079-1094.
474 475 476
Mc Donald, C.J., & Devon, M. J. (2002). Hollow Latex Particles: Synthesis
and Applications. Advances in Colloid and Interface Science, 99, 181-213. Muzzarelli, R.A.A. (1977). Chitin. Oxford: Pergamon Press, (pp.132).
Page 25 of 39
26 Nishat, N., Khan, S.A., Rasool, R., & Parveen, S. (2011). Synthesis, Spectral
478
Characterization and Biocidal Activity of Thermally Stable Polymeric Schiff Base and
479
Its Polymer Metal Complexes. Journal of Inorganic and Organometallic Polymers,
480
21, 673-681.
ip t
477
Nuasaen, S., & Tangboriboonrat, P. (2013). Highly Charged Hollow Latex
482
Particles Prepared via Seeded Emulsion Polymerization. Journal of Colloid and
483
Interface Science, 396, 75-82.
us
cr
481
Nypelo, T., Osterberg, M., Zu, X., & Laine, J. (2011). Preparation of Ultrathin
485
Coating Layers Using Surface Modified Silica Nanoparticles. Colloids and Surfaces
486
A: Physicochemical and Engineering Aspects, 392, 313-321.
M
an
484
Obee, T.N., & Brown, R.T. (1995). TiO2 Photocatalysis for Indoor Air
488
Applications: Effects of Humidity and Trace Contaminant Levels on the Oxidation
489
Rates of Formaldehyde, Toluene, and 1, 3-Butadiene. Environmental Science &
490
Technology, 29, 1223-1231.
te
Ac ce p
491
d
487
Peng, C., Thio, Y.S., & Gerhardt, R.A. (2010). Enhancing the Layer-by-Layer
492
Assembly of Indium Tin Oxide Thin Films by Using Polyethyleneimine. Journal of
493
Physical Chemistry C, 114, 9685-9692.
494
Polpanich, D., Tangboriboonrat, P., & Elaissari, A. (2005). The effect of
495
Acrylic Acid Amount on the Colloidal Properties of Polystyrene Latex. Colloid &
496
Polymer Science, 284, 183-191.
497 498
Rinaudo, M. (2008). Main Properties and Current Applications of Some Polysaccharides as Biomaterials. Polymer International, 57, 397-430.
Page 26 of 39
27 499
Silva, C. A., & Galembeck, F. (2010). Void Formation and Opacity in Latex
500
Films with Aluminum Phosphate Particles. Colloids and Surfaces A: Physicochemical
501
and Engineering Aspects, 363, 146-154. Trybala, A., Szyk-Warszynska, L., &
Warszynski, P. (2009).The Effect of
ip t
502 503
Anchoring PEI Layer on the Build-up of Polyelectrolyte Multilayer Films at
504
Homogeneous
505
Physicochemical and Engineering Aspects, 343, 127-132.
Surfaces.
Colloids
and
Surfaces
cr
Heterogeneous
A:
us
and
Wada, T., Uragami, T., & Matoba, Y. (2005). Chitosan-Hybridized Acrylic
507
Resins Prepared in Emulsion Polymerizations and Their Application as Interior
508
Finishing Coating. Journal of Coating Technology and Research, 2, 577-582. Wang, X., Cui, F.,
M
509
an
506
Lin, J., Ding, B., Yu, J., & Al-Deyab, S.S. (2012).
Functionalized Nanoporous TiO2 Fibers on Quartz Crystal Microbalance Platform for
511
Formaldehyde Sensor. Sensors and Actuators B: Chemical, 171-172, 658-665.
te
d
510
Wazed Ali, S., Rajendran, S., & Joshi, M. (2011). Synthesis and
513
Characterization of Chitosan and Silver Loaded Chitosan Nanoparticles for Bioactive
514
Polyester. Carbohydrate Polymers, 83, 438-446.
515
Ac ce p
512
Yang, K., Liu, Y., Yu, C., & Chen, B. (2011). Fabrication of Chitosan/Silver
516
Nanocomposites based on Electrochemical Methods for Removing Formaldehyde in
517
Air. Materials Chemistry and Physics, 126, 993-997.
518
Zhou, X., Cheng, X.J., Liu, W.F., Li, J., Ren, L.H., Dang, Q.F., Feng, C.,
519
Chen, X.G. (2013). Optimization and Characteristics of Preparing Chitosan
520
Microspheres Using Response Surface Methodology. Journal of Applied Polymer
521
Science, 127, 4433-4439.
Page 27 of 39
28 522
Zhu, Y., Li, H., Zheng, Q., Xu, J., & Li, X. (2012). Amine-Functionalized SBA-
523
15 with Uniform Morphology and Well-Defined Mesostructure for Highly Sensitive
524
Chemosensors to Detect Formaldehyde Vapor. Langmuir, 28, 7843-7850.
ip t
525
Ac ce p
te
d
M
an
us
cr
526
Page 28 of 39
29 Table
527
Table 1 Weight compositions, determined from TGA, of HL, HL-chitosan and HL-PEI
528
particles Sample
Weight composition (%) at Tdecomposition
290
445-455 non-decomposed fraction
HL
-
-
86.5
8.3
HL-chitosan
-
4.5
77.4
12.9
12.7
-
72.5
6.1
4.8 13.9
M
529
an
HL
chitosan or PEI in
us
250
HL-PEI
Weight (%)
cr
of
ip t
526
Ac ce p
te
d
530
Page 29 of 39
30 530
Figure Captions
531
Figure 1 FTIR spectra of PEI (A), chitosan (B), HL (C), HL-PEI (D) and HL-chitosan
533
(E)
534
Figure 2 Particle size (A) and zeta potential (B) of HL, HL-chitosan and HL-PEI
535
particles and TEM images of HL (C) HL-chitosan (D) and HL-PEI (E)
536
Figure 3 FTIR spectra of chitosan after formaldehyde adsorption at 0 (B), 5(C),
537
15(D), 30(E), 45(F), 60(G), 75(H), 90(I) and 120 min (J), and a different spectrum of
538
chitosan at 120 min adsorption time after subtraction of neat chitosan (A) and
539
reaction between chitosan and formaldehyde (K)
540
Figure 4 FTIR different spectra of formaldehyde-adsorbed chitosan
541
adsorption times: 5(A), 30(B), 60(C), 90(D) and 120 min (E) and FTIR different
542
spectra of heat-treated samples after subtraction of formaldehyde-adsorbed chitosan
543
at various adsorption times: 5(F), 30(G), 60(H), 90(I), 120 min (J)
544
Figure 5 The different spectra of HL-chitosan at various adsorption times: 0 (A),
545
5(B), 45(C), 90(D), and 120(E), after subtraction of HL, and the different spectra of
546
HL-chitosan with a vacuum heat treatment at 0(F), 5(G), 45(H), 90(I) and 120 min
547
(J), after subtraction of HL
548
Figure 6 FTIR spectra of PEI at various formaldehyde adsorption times: 0 (B), 5(C),
549
15(D), 30(E), 45(F), 60(G), 75(H), 90(I) and 120 min (J), and the different spectrum
550
of PEI at 120 min after subtraction of neat PEI (A) and reaction between PEI and
551
formaldehyde (K)
at various
Ac ce p
te
d
M
an
us
cr
ip t
532
Page 30 of 39
31 Figure 7 FTIR spectra of HL-PEI at various adsorption times: 120 (A), 90(B), 75(C),
553
60(D), 45(E), 30(F), 15 (G) and 0 min (H) and HL (I), their different spectra at 120(J),
554
90(K), 60(L), 5(M) and 0 min (N), after subtraction of HL
555
Figure S1 TGA and DTG thermograms of HL (A), HL-chitosan (B) and HL-PEI (C)
556
Figure S2 FTIR spectra of HL (A) and HL-chitosan at various formaldehyde
557
adsorption times: 5 (B), 15(C), 30(D), 45(E), 75(F), 90(G), 120 min (H)
558
Figure S3 FTIR spectra of HL(A) and HL-chitosan at various adsorption times with a
559
vacuum heat treatment: 0(B), 5(C), 15(D), 30(E), 45(F), 60(G), 75(H), 90 (I) and 120
560
min(J)
561
Figure S4 FTIR different spectra, at various formaldehyde adsorption times, after
562
subtraction of neat PEI: 120(A), 90(B), 75(C), 60(D), 45(E), 30 (F), 15(G) and 5 min
563
(H)
566 567
cr
us
an
M
d te
565
Ac ce p
564
ip t
552
Page 31 of 39
Ac
ce
pt
ed
M
an
us
cr
i
Figure 1
Page 32 of 39
Ac
ce
pt
ed
M
an
us
cr
i
Figure 2
Page 33 of 39
Ac
ce
pt
ed
M
an
us
cr
i
Figure 3
Page 34 of 39
Ac ce p
te
d
M
an
us
cr
ip t
Figure 4
Page 35 of 39
Ac
ce
pt
ed
M
an
us
cr
i
Figure 5
Page 36 of 39
Ac
ce
pt
ed
M
an
us
cr
i
Figure 6
Page 37 of 39
Ac
ce
pt
ed
M
an
us
cr
i
Figure 7
Page 38 of 39
Ac
ce
pt
ed
M
an
us
cr
i
Graphical Abstract
Page 39 of 39
