ArticlePDF Available

Reparation and characterization of amidated pectin based polymer electrolyte membranes



The work presents the synthesis and characterization of amidated pectin (AP) based polymer electrolyte membranes (PEM) crosslinked with glutaraldehyde (GA). The prepared membranes are characterized by Fourier transform infrared spectroscopy (FTIR), organic elemental analysis, X-ray diffraction studies (XRD), thermogravimetric analysis (TGA) and impedance spectroscopy. Mechanical properties of the membranes are evaluated by tensile tests. The degree of amidation (DA), molar and mass reaction yields (Y(M) and Y(N)) are calculated based on the results of organic elemental analysis. FTIR spectroscopy indicated the presence of primary and secondary amide absorption bands. XRD pattern of membranes clearly indicates that there is a considerable increase in crystallinity as compared to parent pectin. TGA studies indicate that AP is less thermally stable than reference pectin. A maximum room temperature conductivity of 1.098 x 10(-3) Scm(-1) is obtained in the membrane, which is designated as AP-3. These properties make them good candidates for low cost biopolymer electrolyte membranes for fuel cell applications.
Chinese Journal of Polymer Science Vol. 27, No. 5, (2009), 639
646 Chinese Journal of
Polymer Science
©2009 World Scientific
R.K. Mishraa, A. Anisb, S. Mondalb*, M. Dutta and A.K. Banthiab
a Department of Polymer Science, Bundelkhand University, Jhansi 284128, India
b Materials Science Center, Indian Institute of Technology, Kharagpur 721302, India
Abstract The work presents the synthesis and characterization of amidated pectin (AP) based polymer electrolyte
membranes (PEM) crosslinked with glutaraldehyde (GA). The prepared membranes are characterized by Fourier transform
infrared spectroscopy (FTIR), organic elemental analysis, X-ray diffraction studies (XRD), thermogravimetric analysis
(TGA) and impedance spectroscopy. Mechanical properties of the membranes are evaluated by tensile tests. The degree of
amidation (DA), molar and mass reaction yields (YM and YN) are calculated based on the results of organic elemental
analysis. FTIR spectroscopy indicated the presence of primary and secondary amide absorption bands. XRD pattern of
membranes clearly indicates that there is a considerable increase in crystallinity as compared to parent pectin. TGA studies
indicate that AP is less thermally stable than reference pectin. A maximum room temperature conductivity of 1.098 × 103
Scm1 is obtained in the membrane, which is designated as AP-3. These properties make them good candidates for low cost
biopolymer electrolyte membranes for fuel cell applications.
Keywords: Amidated pectin; Proton conducting; Methanol permeability; Impedance spectroscopy; Fuel cell.
Fuel cells have emerged strongly as power sources for stationary and portable applications owing to their high-
energy conversion efficiency, eco-friendly nature and low temperature operation[1, 2]. Methanol has been widely
used as a fuel in direct methanol fuel cell (DMFC) because of its easy handling and low price. It has high energy
density and can be easily generated from natural resources such as coal, gas and biomass. DMFC is expected to
have high and compromising values as clean energy[3, 4]. Among the various types of fuel cells, the polymer
electrolyte membrane fuel cell (PEMFC) has been well established for over five decades and is successfully
used as an electrical power for spacecrafts and submarines[5]. One of the important areas of research in PEMFC
is the development of low cost membranes with low methanol permeability for direct methanol fuel cells
(DMFC). The main reasons for this growing interest is the high cost, limit of low operating cell temperature and
methanol crossover problems associated with presently used plain perflurosulfonic acid membranes[6, 7]. It has
been reported by few workers that, on suitable chemical modification polymers containing hydroxyl and amine
groups exhibit good conductivities[8, 9]. Applications of biopolymers in electrical devices are not only interesting
but also important for environmental safety. In addition to that, production cost is greatly reduced by using a
biopolymer instead of expensive polymers[10]. Recently some natural polymers have been used as a low cost
electrolyte for the development of polymer electrolyte membrane fuel cell (PEMFC)[11, 12]. Pectin is a complex
carbohydrate polymer that plays an instrumental role in regulating the mechanical properties of plant cell wall[13]
and has several industrial applications related to their thickening and gelling properties[1416]. Chemically, pectin
is a linear chain of poly(
-1,4-galacturonic acids), with varying degree of methylation of carboxylic acid
residues. Chemical modification of pectin can influence their chemical and technological properties. Amidated
pectins are firmly entrenched in the food industry, and they are important pectin derivatives with good gelling
* Corresponding author: S. Mondal, E-mail:
Received May 26, 2008; Revised September 22, 2008; Accepted October 6, 2008
R.K. Mishra et al.
properties. Amidated pectins often replace low methoxyl pectins, since amidated pectins need less calcium, are
less sensitive to precipitation by high amounts of calcium, and their gels are claimed to be thermo-reversible[17,
18]. Some reports were published dealing with the polyelectrolytic properties of amidated pectin in solution and
their calcium binding ability[19] but no such work has been reported on amidated pectin based membranes, which
are ionically conducting. This paper reports the development of ethanolamine-modified pectin (EAMP) based
membranes. The membranes prepared were characterized by FTIR, organic elemental analysis, XRD, TGA,
impedance spectroscopy and tensile tests.
Materials and Methods
Pectin (MW ca. 3.0 × 1041.0 × 105), methanol (AR) and glutaraldehyde (GA) 25% solution were obtained from
Loba-chemie Indoaustranal Co. Mumbai, India. Ethanolamine was obtained from Sisco Research Laboratories
(SRL), Mumbai, India. Hydrochloric acid 35% pure was obtained from Merck Limited, Mumbai, India. Double
distilled water was used throughout the study. Amidated pectin (AP) was synthesized according to the method
described elsewhere[20].
Preparation of Membranes
The amidated pectin (AP) based membranes crosslinked with GA used in the study were fabricated using
solvent casting technique. A stock viscous solution of APs in water (100 g/L) was prepared by dissolving 2 g of
APs of different concentrations in 20 mL of distilled water and stirring for 2 h at room temperature. To the
dissolved AP solutions 1 mL of glutaraldehyde was added as a crosslinking agent. The resultant mixture was
further stirred for 30 min at room temperature to complete the crosslinking reaction. After that the homogeneous
solution was poured into petri dishes and allowed to dry in a laminar flow chamber. The resulting films were
peeled off from the petri dishes and were characterized. The films so obtained were named AP-1, AP-2, AP-3,
AP-4, AP-5 and AP-6 respectively.
FTIR Spectral Analysis
The FTIR spectra of pectin and AP were taken in the frequency range of 4000400 cm1 using attenuated total
reflectance (ATR) mode with the help of an FTIR spectrophotometer (NEXUS870, Thermo Nicolet
Organic Elemental Analysis
Elemental analysis was obtained from a 2400 series II CHN analyzer (Perkin Elmer). The estimation of only
three elements i.e. carbon, hydrogen and nitrogen was done.
X-ray Diffraction Studies
For the X-ray diffraction studies the raw materials were subjected to X-ray diffraction (XRD-PW 1700, Philips,
USA) using Cu K
radiation generated at 40 kV and 40 mA; the diffraction angle, 2
values were in the range
of 10°70°.
Thermogravimetric Analysis
Thermal stability of pectin and AP membranes was carried out by using NETZSCH TG 209 F1 at a heating rate
of 10 K/min, with nitrogen flushed at 100 mL/min.
Tensile Studies
The tensile studies of the AP based composite membranes were carried out using a Hounsfield H10KS tensile
testing machine.
Crosshead speed: 50 mm/min; Temperature: 18°C; Relative humidity: 60%.
Water Uptake
The water uptake of the hybrid membranes was determined by measuring the change in the weight before and
after hydration. The membrane was immersed in deionized water for 24 h, and the water attached on surface of
the membrane was carefully removed with filter paper. After that, the wetted membrane weight was determined
Polymer Electrolyte Membranes Based on Pectin 641
instantaneously. The water uptake was calculated by using the following equation:
Water uptake =
MM (1)
where Mw and Md are the weight of the swollen polymer and the dry polymer in grams, respectively[21].
Methanol Permeability Measurements
The measurement of methanol diffusion coefficient through the composite membranes was performed using an
in house built diffusion cell having two compartments, which were separated by the membrane situated
horizontally. Prior to diffusion coefficient measurement, the membranes were equilibrated in aqueous methanol
solution 50% V/V for 24 h, and the experiments were carried out at room temperature (25°C). The methanol
concentration of the receptor compartment was estimated using a differential refractometer (Photal OTSUKA
Electronics, DRM-1021); the differential refractometer was highly sensitive to the presence of methanol. The
change in refractive index of the diffusion samples was averaged over 52 scans in the differential refractometer
to determine the change in refractive index. The methanol diffusion coefficients for the PEMs was calculated
using the following equation[22]:
sample ln cc
= (2)
where D is the methanol diffusion coefficient, l is the thickness of the membrane, Vsample is the volume of the
sample solution; A is the cross-section area of membrane and texp is the time interval during which diffusion
occurs, c
methanol is the concentration of methanol fed in the donor compartment, c1 is the concentration of
methanol in receptor compartment at t = 0, and c2 is the concentration of methanol in the receptor compartment
at t = texp.
Impedance Spectroscopy
Conductivity measurements were made at room temperature (25°C) after equilibrating the membrane in
deionized water for 24 h. The conductivity cell was composed of two stainless steel electrodes of 16 mm
diameter. The membrane sample was sandwiched in between stainless steel electrodes. AC impedance spectra of
the membranes were recorded from 40 Hz to 15 MHz with amplitude of 10 mV using an Agilent 4294A
Precision Impedance Analyzer. The bulk resistance of the membrane was determined from the high frequency
intercept of the imaginary component of impedance with the real axis. The conductivity was calculated using the
following equation:
, l, R, and A denote the membrane conductivity, membrane thickness, the bulk resistance of the
membrane, and the cross-sectional area of the membrane, respectively[23].
The reaction mechanism of amidation of pectin with ethanolamine (Sinitsya et al.) is depicted below.
R.K. Mishra et al.
Elemental Analysis
The results of elemental analysis (C, H, N) of pectin and modified pectin (AP) membrane and calculated values
of DA, DM, YM and YN are listed in Table 1[20]. It is evident from the table that pectin does not show any
significant presence of nitrogen, but in case of AP membranes, the analysis shows a considerable increase in
nitrogen content with increasing concentration of ethanolamine. It can be clearly observed from Table 1 that the
degree of amidation (DA%) of pectin increased with increase in concentration of ethanolamine. This is due to
incorporation of amide groups or amine moieties in a greater extent on the pectin structure after amidation
Where DA is the degree of amidation, YM the mass yield of the reaction, i.e. the relative mass of bonded amine
(%) in reaction product, YN the molar yield of the reaction i.e. the relative content of ester groups substituted by
amine (%), MH the hydrogen content (%), MN the nitrogen content (%) and MC the carbon content (%), MA the
molar mass of amine (gmol1), 73 is the degree of methylation (DM) of original pectin (%)[24].
Table 1. Results of elemental analysis of AP based membranes
Sample identity MC (%) MH (%) MN (%) DA (%) DM (%) YM (%) YN (%)
Pectin 36.27 5.85 0.39
AP-1 33.08 6.21 1.11 22.46 31 0.39 6.840
AP-2 38.31 5.56 2.17 33.00 33 1.55 13.69
AP-3 32.56 7.25 2.83 59.61 34 3.03 20.54
AP-4 31.55 7.32 3.13 68.83 32 4.47 27.39
AP-5 33.02 7.71 4.17 88.45 29 7.44 34.24
AP-6 32.92 7.74 4.30 91.48 35 9.21 41.09
Fig. 1 FTIR spectra of (a) pure pectin and (b) amidated pectin based membrane (AP-6)
Polymer Electrolyte Membranes Based on Pectin 643
FTIR Spectral Analysis
The FTIR spectrum of the pure pectin is shown in Fig. 1(a). The spectrum showed peak at 3402 cm1 due to the
stretching of OH groups. The peak at 2939 cm1 indicated CH stretching vibration. The peaks at 1460 and
1332 cm1 could be assigned to CH2 scissoring and OH bending vibration peaks, respectively. The peak at
1010 and 1647 cm1 suggested CHOCH stretching and CO stretching vibration peaks. The peak at
1157 cm1 suggested the presence of CHOH in aliphatic cyclic secondary alcohol[25, 26]. Figure 1(b) shows
the FTIR spectrum of AP membrane. The carboxyl vibration region 15001900 cm1 is most important for our
analysis. The acid form of modified pectin has two important bands at 1672 cm1 (amide I) and 1595 cm1
(amide II)[27]. The presence of these two bands and absence of intense carboxylate stretching bands indicated
that the subsituents were grafted on pectin chain by covalent amide bonds. The intense band near 2925 cm1 was
due to symmetric CH stretching vibrations of methylene groups. This effect is due to the increase of CH
bond content after amidation reaction. The peak at 1402 cm1 suggested CH bending of CH2 groups. The
peak at 1016 cm1 suggested OH bending, and the peak at 1074 cm1 indicated the presence of secondary
alcohol (characteristic peak of CHOH in cyclic alcohol CO stretch).
X-ray Diffraction Analysis
Figure 2 shows XRD patterns of the pectin and AP based membrane respectively. X-ray diffractogram of the AP
based membrane shows an intense peak at 35.17° (2θ), where as the diffractogram of pectin indicated a single
weak wide diffraction peak at ca. 13.34° (2θ). From the diffractograms of reference pectin and AP based
membranes one can easily justify that the pure pectin is a completely amorphous material because there is no
intense peak except a weak wide diffraction peak at 13.34°, whereas the diffractogram of AP based membrane
shows an intense peak at 2θ equal to 35.17°. The crystallinity of the AP membranes increases after amidation
due to the formation of hydrogen bonding in the amidated pectin. From the XRD plots of pectin and AP
membranes the crystallinity was calculated[28], and it was found to be 0.81% and 49.09%, respectively, which
indicates that AP is a partially crystalline material as compared to reference pectin.
Water Uptake
The water uptakes of AP based membranes with respect to degree of amidation (DA) of prepared membranes
are depicted in Fig. 3. It is evident from the figure that at first there is a considerable increase in water uptake of
the AP membranes with increase in degree of amidation (DA) to 68.83% but further increase in DA leads to
decrease in water uptake of the membranes. The increase in water uptake up to certain level may be attributed to
the hydrophilic nature of AP but after that, there is a considerable decrease in water uptake due to the resistance
offered by the crosslinked networks to further uptake of water by the AP based membranes.
Fig. 2 XRD patterns of (a) pure pectin and (b) AP
based membrane (AP-6) Fig. 3 Water uptake verses degree of amidation of
AP membranes
R.K. Mishra et al.
Mechanical Properties
The tensile strength and elongation at break of the AP membranes are shown in Fig. 4. It is evident from the
figure that the membranes which are designated as AP-1, AP-2, AP-3, AP-4, their tensile strengths are almost
comparable (0.363, 0.267, 0.433 and 0.314 MPa), whereas the tensile strength of the AP-5, AP-6 are quite high
(1.58 and 1.013 MPa) as compared to the other four membranes and the highest strength (1.58 MPa) was
observed in the case of AP-5. Whereas the elongation at break of the AP membranes increases gradually with
increase in degree of amidation (DA) of the membranes but after that a decrease in elongation was observed.
The low tensile strength of the four membranes were attributed to the presence of unreacted pectin that might be
present in the membranes causes reduction in the tensile strength of the prepared AP based membranes.
Fig. 4 Tensile strength and elongation at break of AP based membranes (AP-1 to AP-6)
Thermo Gravimetric Analysis (TGA)
The thermograms of pectin and AP membrane obtained at heating rate of 10 K/min under nitrogen atmosphere
are shown in Fig. 5. It can be observed from the thermogram of pectin that thermal loss in weight starts in the
range of 3576°C, which is associated with loss of absorbed moisture in the sample, and in second step
decomposition was observed between 195350°C[29, 30]. In this range the sample rapidly losses 60% of its total
weight up to 350°C. Therefore, it shows a two-step degradation process. Beyond 350°C thermogram shows that
weight loss is slow and gradual up to 697°C. In this temperature range 350697°C the sample loses 15% of its
original weight. The maximum rate of weight loss was observed at 235°C. Whereas the thermogram of AP
membrane shows a three-step degradation process. The first weight loss starts at 77194°C, which is due to
moisture vaporization. The second weight loss at 200350°C is due to thermal degradation of the EAMP
membrane. The third weight loss at 400500°C is due to the by-product generated by the thermal
Fig. 5 TGA of (a) pure pectin and (b) AP-6 membrane
Polymer Electrolyte Membranes Based on Pectin 645
decomposition of modified pectin (AP) based membrane. Up to 600°C 86% loss in total weight was observed
for AP membrane as compared to 72% weight loss in pectin. This indicates the lower thermal stability of AP as
compared to parent pectin.
Methanol Permeability
Table 2 shows the methanol permeability of amidated pectin (AP) based polymer electrolyte membranes. It can
be observed from the table that there is a regular increase in methanol permeability of the AP based membranes
with increase in DA of the membranes. The methanol permeability was directly correlated with the water uptake
of the membranes because the highest methanol permeability of 1.98 × 106 was observed in the membrane AP-
4 that had the highest water uptake. But after that a decrease in methanol permeability was observed. The lower
methanol permeability of 1.22 × 106 was observed in the membrane of AP-1.
Table 2. Result of methanol permeability of AP based membranes
Sample identity Membrane thickness (µm) Methanol diff. coefficient (cm2s1)
AP-1 190 1.22 × 106
AP-2 270 1.27 × 106
AP-3 270 1.30 × 106
AP-4 420 1.98 × 106
AP-5 165 1.42 × 106
AP-6 245 1.35 × 106
Proton Conductivity Analysis
Figure 6 shows the proton conductivity as function of degree of amidation. Here the proton conductivity was of
the order of 103 Scm1. The proton conductivity initially increases with increase in degree of amidation but with
further increase in degree of amidation, a decrease in conductivity of the membranes is observed. The drop in
the conductivity is due to the decrease in water uptake of these membranes because the presence of water assists
in the movement of the protons through the polymer matrix by forming hydronium ions. A maximum
conductivity of 1.098 × 103 Scm1 was obtained for the membrane designated AP-3. The reasonably good
conductivity of the membrane can be attributed to the residual hydroxyl and amine groups present in the
membranes, which give rise to hydrophilic regions in the polymer due to strong affinity towards water. This
hydrophilic area formed around the clusters of side chains leads to absorption of water, which enables easy
proton transfer[31].
Fig. 6 Degree of amidation verses proton conductivity of AP membranes
In the present study, amidated pectin based polymer electrolyte membranes have been prepared by crosslinking
with glutaraldehyde (GA). FTIR spectra of AP based membranes indicate presence of amide bands (amide I,
amide II) and N-alkyl absorption bands. The data obtained were in good agreement with other analytical
methods (organic elemental analysis). The XRD study indicates that there is considerable increase in
R.K. Mishra et al.
crystallinity of pectin after chemical modification with ethanolamine. Mechanical properties of the AP
membranes were found to be sufficient. The water uptake measurement of the membranes shows increase in
water holding capacity of the membranes with increase in degree of amidation of pectin up to 68.83 % after
which a decrease in water holding capacity of the membranes was observed. The proton conductivity of AP
membranes was measured at room temperature, the highest proton conductivity of 1.098 × 103 Scm1 was
observed in the membrane AP-3. Further, due to the high ionic conductivity of the membrane it can be used as
low cost proton conducting biopolymer electrolyte membranes for fuel cell applications.
1 Smitha, B., Sridhar, S. and Khan, A.A., J. Membr. Sci., 2003, 225: 63
2 Yu, J., Yi, B., Xing, D., Liu, F., Shao, Z. and Fu, Y., J. Power Sources, 2002, 4937: 1
3 Jorrisen, L., Gogel, V., Kerres, J. and Garche, J., J. Power Sources, 2002, 105: 267
4 Kordesh, K.V., J. Electrochem. Soc., 1978, 25: 77
5 Smitha, B., Sridhar, S. and Khan, A.A., J. Power Sources, 2006, 159: 846
6 Savadogo, O., J. Power Sources, 2004,127: 135
7 Yamada, M. and Honma, I., Electrochem. Acta, 2005, 50: 2837
8 Kreuer, K.D., Chem. Phys. Chem., 2002, 3: 771
9 Kerrers, J.A., J. Membr. Sci., 2001, 185: 3
10 Kreuer, K.D., J. Membr. Sci., 2001, 185: 29
11 Rikukawa, M. and Sanui, K., Prog. Polym. Sci., 2000, 25: 1463
12 Schuster, M.F.H., Meyer, W.H., Schuster, M. and Kreuerm, K.D., Chem. Mater., 2004, 16: 329
13 McCann, M.C. and Roberts, K., “Plant cell wall architecture: the role of pectins”, In: “Pectins and Pectinases”, Progress
in Biotechnology, Vol. 14, ed. by Visser, G. and Voragen, A.G.J., Elsevier Sciences, B.V. Amsterdam, 1996, p.91
14 May, C.D., Carbohy. Polym., 1990, 12: 79
15 Axelos, M.A.V. and Thibault, J.F., “The chemistry of low-methoxyl pectin gelation, In: “The Chemistry and
Technology of Pectin”, ed. by Walter, R.H., Academic Press Inc, San Diego, California, 1991, p.109
16 Thakur, B.R., Singh, R.K. and Handa, A.K., Crit. Rev. Food Sci. Nutri., 1997, 37: 47
17 Gross, M.O., Thesis, University of Georgia, 1979
18 van Alebeek, G.J.W.M., Schols, H.A. and Voragen, A.G.J., Carbohy. Polym., 2001, 46: 311
19 Racape, E., Thiaboult, J.F., Reitsma, J.C.E. and Pilink, W., Biopolymers, 1989, 28: 1435
20 Sinitsya, A., Copikova, J., Prutyanov, V., Skoblya, S. and Machovic, V., Carbohy. Polym., 2000, 42: 359
21 Zhang, Y. J., Huang, Y.D. and Wang, L., Solid State Ionics, 2006, 177: 65
22 Di Noto, V., Vittedelo, M., Zago, V., Pace, G. and Vidali, M., Electrochim. Acta, 2006, 51: 1602
23 Xue, S. and Yin, G., Polymer, 2006, 47: 5044
24 Flippov, M.P. and Kuzminov, V.I., Zhurnal Analiticheskoj Khimii, 1971, 26: 143
25 Sinitsya, A., Copikova, J., Matejka, P. and Machovic,V., Carbohy. Polym., 2003, 54: 97
26 Coimbra, M.A., Barros, A., Barros, M., Rutledge, D.N. and Delgadillo, I., Carbohy. Polym., 1998, 37: 241
27 Sinitsya, A., Copikova, J., Marounek, M., Micochova, P., Sehelnkova, L., Skoblya, S., Havlatova, H., Matcjika, P.,
Maryska, M. and Machovic, V., Carbohy. Polym., 2004, 56: 169
28 Bhat, A.H. and Banthia, A.K., J. Appl. Polym. Sci., 2007, 103: 238
29 Stoll, U.E., Kunzek, H. and Dongowski, G., Food Hydrocolloids, 2007, 21: 1101
30 Fisher, T., Hajaligol, M., Waymack, B. and Kellogg, D., J. Analyt. & Appl. Pyrol., 2002, 62: 331
31 Miyatake, K., Oyaizu, K., Tsuchida, E. and Hay, A.S., Macromolecules, 2001, 34: 2065
... Following treatments in treated groups, a significant decrease in colonic MPO and MDA levels with an increase in GSH level were detected in rats with AA-induced colitis. Many studies reported that taurine, CS-NPs, and PT-NPs reduced inflammation and ROS generation [23,[36][37][38][39]48,49]. The effect of oxidative stress was also proved by colon histopathological results in the untreated colitis control group. ...
... Furthermore, it enhanced the healing of 2,4,6-trinitrobenzene sulfonic acid (TNBS)-colitis induced in rats when used as a colon-specific carrier for 5-aminosalicylic acid [21]. Pectin shares very similar properties with chitosan, such as non-toxic, biodegradable, antioxidant, anti-inflammatory, and resistant to the digestive enzymes in the gastrointestinal tract and degraded only by the microflora in the colon [23,48,49]. Besides, our in vivo results for inflammatory and oxidative stress markers and histopathology support this characterization. ...
Owing to the poor outcomes and adverse side effects of existing ulcerative colitis drugs, the study aimed to develop an alternative nano-based treatment approach. The study was designed to characterize the in vitro and in vivo properties of taurine, taurine-loaded chitosan pectin nanoparticles (Tau-CS-PT-NPs) and chitosan pectin nanoparticles (CS-PT-NPs) in the therapy of acetic acid (AA)-induced colitis in rats. CS-PT-NPs and Tau-CS-PT-NPs were prepared by ionic gelation method then in vitro characterized, including transmission electron microscopy (TEM), polydispersity index (PDI), zeta potential, Fourier transform infrared (FTIR) spectroscopy, encapsulation efficiency (EE), and drug release profile. Following colitis induction, rats orally received free taurine, Tau-CS-PT-NPs, and CS-PT-NPs once per day for six days. The sizes of Tau-CS-PT-NPs and CS-PT-NPs were 74.17 ± 2.88 nm and 42.22 ± 2.41 nm, respectively. EE was about 69.09 ± 1.58%; furthermore, 60% of taurine was released in 4 h in simulated colon content. AA-induced colitis in untreated rats led to necrosis of colon tissues and a significant increase in interleukin-1beta (IL-1β), Tumor Necrosis Factor-alpha (TNF-α), myeloperoxidase (MPO), and malondialdehyde (MDA) levels associated with a remarkable reduction in glutathione (GSH) level in colon tissue in comparison to control group. Treatment with taurine, Tau-CS-PT-NPs, and CS-PT-NPs partly reversed these effects. The present study demonstrated that the administration of free taurine, CS-PT-NPs, and Tau-CS-PT-NPs exerted beneficial effects in acetic acid-induced colitis by their anti-inflammatory and antioxidant activities. The best therapeutic effect was observed in animals treated with taurine-loaded chitosan pectin nanoparticles.
... The 1 st thermal degradation stage of OC occurred nearby 250 • C with 44.67 % weight loss, which was well in agreement with previous reports (Maciel, Yoshida, & Franco, 2015). The 2 nd degradation stage of OC happened at 540 • C, which was attributed to long-chain thermal degradation of the OC (Mishra, Anis, Mondal, Dutt, & Banthia, 2009). On the other hand, the degradation of AP was observed at 304 • C with a weight loss of 64.83 % and at 587 • C with a weight loss of 32.39 %. ...
... AP- OC-65 hydrogel with larger pore size and less AP% showed a superior swelling capability, while, AP-OC-80 hydrogel with smaller pore size and higher AP% performed the inferior swelling capability. This result might be explained by the large number of hydrophilic groups and the porous 3D structure in both AP and OC hydrogels (Mishra et al., 2009). Large pore size and optimizing of the binding sites could effectively facilitate the swelling capability of the hydrogel (Pourjavadi, Bardajee, & Soleyman, 2009). ...
Hydrogel can provide a favorable moisture environment for skin wound healing. In this study, a novel in-situ crosslinked injectable hydrogel was prepared using the water-soluble amidated pectin (AP) and oxidized chitosan (OC) through Schiff-base reaction without any chemical crosslinker. The influence of AP content on the properties of the hydrogel was systemically investigated. It showed that gelation time, pore structure, swelling capability and degradability of the hydrogel can be tuned by varying the content of amine and aldehyde groups from AP and OC. All the porous hydrogels with various AP contents (65%, 70%, and 80%) presented desirable gelation time, swelling property, high hemocompatibility and biocompatibility. Particularly, AP-OC-65 hydrogel presented superior swelling capability and better hemo- and bio-compatibility, owing to more residual amine sites in the hydrogel. Therefore, the injectable AP-OC-65 hydrogel has a greater potential for application to wound dressing or skin substitute.
... Therefore, biopolymer electrolytes are a good alternative to synthetic electrolytes, by being cost-effective and environmentally friendly [3]. Electrolytes based on various biopolymers such as chitosan [4], starch [2,5], agar-agar [6], arabic gum [7], carrageenan [8], tamarind seed polysaccharide [9], Tragacanth [10,11] cellulose and its derivatives [12], pectin [13], alginate [14], xanthan gum [15], gellan gum [16], polylactic acid and vegetable oil-based polymer [17] are studied. Biopolymers are obtained directly or derived from biomass such as polysaccharides, proteins, and lipids. ...
Full-text available
A proton conducting natural polymer electrolyte based on guar gum and ammonium thiocyanate has been prepared by solution casting method using distilled water as solvent. FTIR confirms the complex formation between polymer and salt. Using the FTIR deconvolution method, ion transport parameters were calculated. XRD spectra reveal the amorphous nature of the polymer membranes. Ionic conductivity of 4.91 × 10–3 Scm−1 is measured for the film containing 1.2 g of GG and 0.6 g of ammonium thiocyanate at room temperature. The glass transition temperature for the highest ion-conducting membrane is found to be 86.4 °C from DSC analysis. A high value of ionic transference number implies that conduction occurs primarily due to mobile ionic species. LSV studies reveal the electrochemical stability of the polymer electrolyte as 2 V. A proton battery is constructed using the highest conducting polymer electrolyte. Its OCV and short circuit current were measured to be 1.33 V and 10.3 mA. Discharge characteristics using different loads were also studied.
... Pectin is primarily derived from citrus and apple peels, and it also has a number of industrial applications associated with its gelling properties [22]. Pectin-based, ethanolamine [23] and diethanolamine [24] modified polymer electrolyte membranes for the fuel cells have also been reported. This indicates that pectin materials exhibit proton conductivity, an important property of PEMFC electrocatalytic systems. ...
Full-text available
A number of nickel complexes of sodium pectate with varied Ni2+ content have been synthesized and characterized. The presence of the proton conductivity, the possibility of the formation of a dense spatial network of transition metals in these coordination biopolymers, and the immobilization of transition ions in the catalytic sites of this class of compounds make them promising for proton-exchange membrane fuel cells. It has been established that the catalytic system composed of a coordination biopolymer with 20% substitution of sodium ions for divalent nickel ions, Ni (20%)-NaPG, is the leading catalyst in the series of 5, 15, 20, 25, 35% substituted pectates. Among the possible reasons for the improvement in performance the larger specific surface area of this sample compared to the other studied materials and the narrowest distribution of the vertical size of metal arrays were registered. The highest activity during CV and proximity to four-electron transfer during the catalytic cycle have also been observed for this compound.
... The band at around 1560 cm −1 corresponded to the protein amide in the pectin molecules [62]. The peak of 1402 cm −1 suggested -CH bending of -CH 2 groups [63]. The peaks between 1320 cm −1 and 1000 cm −1 showed the presence of alcohols, esters, ethers, and carboxylic acids (C-O stretch) [34]. ...
Full-text available
Grape pomace is one of the most abundant by-products generated from the wine industry. This by-product is a complex substrate consisted of polysaccharides, proanthocyanidins, acid pectic substances, structural proteins, lignin, and polyphenols. In an effort to valorize this material, the present study focused on the influence of extraction conditions on the yield and physico-chemical parameters of pectin. The following conditions, such as grape pomace variety (Fetească Neagră and Rară Neagră), acid type (citric, sulfuric, and nitric), particle size intervals (<125 µm, ≥125–<200 µm and ≥200–<300 µm), temperature (70, 80 and 90 °C), pH (1, 2 and 3), and extraction time (1, 2, and 3 h) were established in order to optimize the extraction of pectin. The results showed that acid type, particle size intervals, temperature, time, and pH had a significant influence on the yield and physico-chemical parameters of pectin extracted from grape pomace. According to the obtained results, the highest yield, galacturonic acid content, degree of esterification, methoxyl content, molecular, and equivalent weight of pectin were acquired for the extraction with citric acid at pH 2, particle size interval of ≥125–<200 µm, and temperature of 90 °C for 3 h. FT-IR analysis confirmed the presence of functional groups in the fingerprint region of identification for polysaccharide in the extracted pectin.
... The absorption around 1000 -1200 cm − 1 are the distinctive absorbance region of galacturonic acid, identifying the existence of pectin (Wang and Jin, 2009). In addition to the FT-IR features of the pectin, the data obtained regarding the XRD pattern in this study provides understanding on the overall structure of the extracted pectin in terms of crystallinity and this observation is consistent with the reports of Wathoni et al. (2019), Lopez-sanchez et al. (2016 and Mishra (2009), on the amorphous and crystalline nature of pectin. While the pectin in this study shared similar XRD pattern, factors such as the source of pectin, method of extraction and the extractant may be responsible for the variation in the structural organization of the pectin generally (Lutz et al., 2009). ...
Pectin polysaccharides are characterized with alternating units of a-1,4-linked d-galacturonic acid and a-1,2-l-rhamnose, alongside other sugar moieties. Currently, pectins are attracting research interests due to their pharmacological applications and potential for development of industrial and health products. Here, functional characterization and biological activity of novel pectins from an underutilized plant product, Parkia biglobosa pulp, as possible anti-inflammatory agent is reported for the first time. Pectin was extracted at different pH (2, 5 and 7) conditions, characterized and evaluated for anti-inflammatory properties using methods such as cytometric bead assay complemented with real-time assay, enzyme-linked immunosorbent and membrane stabilization assays. Of the three pectins (P2, P5, and P7) obtained, P5 had the highest yield (40.48%) and lowest moisture content (6.55%), while there was no significant difference in water and oil holding capacities between the pectins. The P5 has a half-maximal concentration of 65.5 ± 0.5 μg/mL in TZM-bl cells and the viability was confirmed by the real time assay through the detection of growth pattern treatment with P5 relative to the control cells. Furthermore, P5 (25 μg/mL) significantly inhibited the production of pro-inflammatory cytokines and nitric oxide levels, while the c-Jun in activator protein-1 was stimulated. These observations are indicative of potential anti-inflammatory attributes of the pectin and was further supported by the capability of P5 in stabilizing red blood cell membranes against hemolytic damage. The findings from this study have lent credence to the promising industrial and pharmacological applications of pectin in the development of anti-inflammatory drugs.
In the current study, the facile method of 5-amino-1-phenyl-3-(thiophen-2-yl)-1H-pyrazole-4‑carbonitrile (pyrazole compound) functionalization was introduced to synthesize the new kind of pectin-based material with high functionality and hydrophilicity. The obtained pyrazole compound/pectin (PCPT) hybrid was characterized by SEM, XRD, FTIR, and EDX. Consequently, it was incorporated into the polyethersulfone (PES) nanofiltration (NF) membrane at different loadings. The pectin (PT) composite membranes (PT-0.3 and PT-0.5) were also prepared to further prove the influence of the used PT functionalization method on membrane performance. The surface properties and filtration performance of the composite membranes were studied. All composite membranes showed higher pure water flux compared to the bare membrane (PT-0) and in the best case, the pure water flux value of 43.22 L/m²h was obtained for the 0.3 wt% PCPT composite membrane (PCPT-0.3). PCPT-0.3 showed the highest mean pore size, porosity, surface hydrophilicity, smoothness, and negative charge among all prepared composite membranes. After incorporation of PCPT hybrid, the salt rejection was considerably enhanced with the sequence of Na2SO4 > NaCl, verifying the typical NF behavior of the membranes. For PCPT-0.3, the rejection of direct red 16 (DR16) and crystal violet (CV) was 99.82 and 98.24%, and the corresponding permeate flux was 40.2 and 40.1 L/m²h, respectively. Pb²⁺, Cu²⁺, and Cd²⁺ rejections were measured 31.00, 32.00, and 32.50% for PT-0, whereas they were 98.09, 98.32, and 98.63% PCPT-0.3, respectively. Moreover, PCPT-0.3 exhibited excellent antifouling properties, nominating the PCPT hybrid as a privileged membrane modifier for the treatment of water/wastewater.
Full-text available
Polymer membranes are emerging substrates for industrial applications like power solutions, toxic metal ion removal and drug delivery technologies. Among all types of membranes polymer electrolyte membranes (PEMs) are current interest, due to their physico-chemical interaction with the guest molecules. PEMs are capable to transport or permeate, adsorb and delivery of molecules, ions and other required reagents. This chapter provides basic concepts as well as the progress with regard to PEMs based science and technology of fuel cells and drug delivery.
This research studied the chemo-sensing of low-cost aminated pectin (PE) obtained by a facile calcination under ammonia gas at temperature no higher than 175 °C without excessive use of alkaline, acid or solvents. The ammonia gas was found to replace the hydroxyl and methoxyl group, enhancing the crystallinity and solubility of the resultant pectin than those calcined in air or in 5% H2. Though the increase of light absorption could be attributed mainly to the dehydration during calcination which caused the formation of CC double bond or aromatic ring, the N incorporation could be important to the photoluminescence (PL) emission. The PL quenching of the blue fluorescent aminated pectin showed a good linearity with the concentration of Cu²⁺, Fe³⁺ and the highest sensitivity toward Cu²⁺ among the investigated metal ions. In order to further increase the PL quenching toward Cu²⁺ and decrease the interference of Fe³⁺, a method involving H2O2 and ultraviolet illumination was developed to catalyze the oxidation of fluorophores on the polymer. This work provides new horizon on the modification and application of pectin in chemosensing.
Full-text available
A series of polymer–acid-modified red mud composite (PRM) materials that consist of poly(vinyl alcohol) (PVA) and layered Red mud (RM) are prepared by effectively dispersing organic PVA matrix into the inorganic layers of modified RM via a conventional solvent casting technique. The as-synthesized PRM materials are typically characterized by Fourier transformation infrared (FTIR) spectroscopy and wide-angle X-ray diffraction. The morphological image of as-synthesized materials is studied by scanning electron microscopy (SEM) and optical microscope (OM). Effects of the material composition on the thermal stability and optical clarity of PVA along with a series of PRM materials freestanding film are also studied by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and UV–vis transmission spectra, respectively. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 238–243, 2007
Blend membranes made of chitosan (CS) and poly(vinyl pyrrolidone) (PVP), were synthesized and characterized for their ion exchange capacity (IEC) and Swelling Index to investigate their applicability in direct methanol fuel cells (DMFC). These membranes were assessed for their intermolecular interactions and thermal stability using FT-IR, X-ray diffraction methods, and TGA. Their methanol permeability and proton conductivity were also estimated and compared to that of Nafion 117. In addition to being effective methanol barriers, the membranes have a high ion exchange capacity (IEC) and possess adequate thermal stability. Crosslinking the polymer blend using glutaraldehyde and sulfuric acid has been particularly effective in producing a reduction of methanol permeability from 9.2×10−8cm2s−1 for CS/PVP blend to 7.3×10−8cm2s−1 for crosslinked CS/PVP blend (GS-CS/PVP) and enhancing the conductivity from 0.019Scm−1 for CS/PVP blend to 0.024Scm−1 for GS-CS/PVP, thereby rendering it more suitable for a DMFC. Low methanol permeability, excellent physico-mechanical properties and above all, the cost effectiveness could make their use in DMFC quite attractive.
From previous biomass decomposition studies, it is well established that thermolysis generally occurs between 200 and 400°C. For most materials, this temperature range constitutes up to 95% of total degradation; nonetheless, secondary decomposition reactions continue to occur in the solid matrix above 400°C. The extent of these reactions, as indicated by the material loss above 400°C, is small, and in the past has been either ignored or included in the primary degradative step. However, this latter step (reactions above 400°C) exhibits many unique characteristics that differentiate it from the primary pyrolysis step and therefore needs to be treated separately. Additionally, it is widely accepted that primary decomposition of biomass material (400°C) involves an aromatization process. In this study, It is shown that the latter step can be deconvoluted from the primary decomposition step, particularly for materials with limited aromaticity, such as cellulose and other carbohydrates. A thermogravimetric analyzer (TGA) coupled with a differential scanning calorimeter (DSC) and mass spectrometer (MS) was used to pyrolyze materials such as cellulose, xylan and other carbohydrates; and a pyroprobe interfaced with a gas chromatograph (GC) and mass spectrometer for product identification. In addition to monitoring the major products for each step, one also monitored and compared the temperatures corresponding to the maximum rate. From this analysis, the DTG results at 20°C min−1 heating rate show that the temperature differences between the peak temperatures of the two decomposition steps are approximately 70, 190, and 200°C for cellulose, pectin, and xylan, respectively. Furthermore, TGA data were used to calculate sets of biomass-specific kinetic parameters for these two steps.
In this contribution an overview is given about the state-of-the-art at the membrane development for proton-conductive polymer (composite) membranes for the application membrane fuel cells, focusing on the membrane developments in this field performed at ICVT.For preparation of the polymers, processes have been developed for sulfonated arylene main-chain polymers as well as for arylene main-chain polymers containing basic N-containing groups, including a lithiation step. Covalently cross-linked polymer membranes have been prepared by alkylation of the sulfinate groups of sulfinate group-containing polymers with α,ω-dihalogenoalkanes. The advantage of the covalently cross-linked ionomer membranes was their dimensional stability even at temperatures of 80–90°C, their main disadvantage their brittleness when drying out, caused by the inflexible covalent network. Sulfonated and basic N-containing polymers (commercial polymers as well as self-developed ones) have been combined to acid–base blends containing ionic cross-links. The main advantage of these membrane type was its flexibility even when dried-out, its good to excellent thermal stability, and the numerous possibilities to combine acidic and basic polymers to blend membranes having fine-tuned properties. The main disadvantage of this membrane type was the insufficient dimension stability at T>70–90°C, caused by breakage of the ionic cross-links, where the ionic cross-links broke as easier as lower the basicity of the polymeric base was. Some of the acid–base blend membranes were applied to H2 membrane fuel cells and to direct methanol fuel cells up to 100°C, yielding the result that these membranes show very good perspectives in the membrane fuel cell application.
Partially amidated pectin derivatives (N-alkyl pectinamides) were prepared from highly methoxylated citrus pectin by treatment with different primary amines in methanol. The characterisation of reaction products was made by elemental analysis, photometry and diffuse reflectance FTIR spectroscopy. N-alkyl pectinamides (secondary amides) had two intense infrared bands (amide I and amide II) shifted to lower wave numbers in comparison with the corresponding bands of commercial amidated pectins (primary amides). In some cases aminolysis of HM pectin caused the appearance of infrared bands from N-substituents. Multiple Gaussian decomposition of the characteristic bands in an IR spectrum in the region of 1850–1500cm−1 were applied for evaluation of the degrees of amidation and methylation. The aminolysis of pectins appears to be an interesting way to produce pectin derivatives with new properties.
This contribution is focused on the conductivity study and the protonic transfer investigation of two new siloxanic membranes. The conductivity of the systems has been studied within the temperature range 5 °C ≤ T ≤ 145 °C, both for pristine and hydrated membranes. Membrane A has been hydrated up to 33.12% in weight, while in B up to 27.76%. The conductivity of these membranes has shown a temperature dependence of the Arrhenius type variable in the interval 1.6 × 10−4 ≤ σA ≤ 2.3 × 10−3 S cm−1 and 1.3 × 10−5 ≤ σB ≤ 2.9 × 10−4 S cm−1, respectively, for A and B. In particular, conductivities of 2 × 10−3 S cm−1 (A) and of 2 × 10−4 S cm−1 (B) at 125 °C were observed.The conductivity mechanism was investigated by using broad band electrical spectroscopy in the region between 40 Hz and 10 MHz. This study, for both the materials has shown the presence at low frequencies (102 ≤ fβ ≤ 104 Hz) of β relaxations related to the sulphonic side chain dynamics. The activation energy measured for this molecular dynamics is about ≅30 kJ mol−1 and corresponds to the typical interaction energy associated with hydrogen bonding. Furthermore, it was observed that the activation energies determined from the conductivity measurements are 12 and 14 kJ mol−1, respectively, for A and B. This shows that the protonic conductivity is strongly influenced by the side chain dynamics and that the charge migration occurs through an ion hopping mechanism between different regions, consisting of micro-clusters of hydration water coordinated with the polar sulphonic groups of the side chains. The comparable activation energies and the values of the conductivity demonstrate that in these systems the conductivity is proportional to the concentration of the sulphonic groups. This shows also that these kinds of membranes, with a high concentration of SO3H are necessary in order to obtain materials with a high protonic conductivity with the capacity to retain water in bulk up to 145 °C.
The polymerization of 2,3,5,6-tetraphenylhydroquinone (or 2,2‘,3,3‘,5,5‘-hexaphenyl-4,4‘-dihydroxybiphenyl) with α,ω-tetrahydroperfluoroalkanediol and decafluorobiphenyl was carried out to synthesize a series of copolymers III (Mw = 49 100−80 900). The copolymers III are composed of arylene ether (10−30 mol %) and fluorinated alkane (90−70 mol %) moieties. The reaction of III with chlorosulfonic acid gave sulfonated polymers IV, which are soluble in polar organic solvents and form flexible and transparent films by casting from solution. The polymers IV have glass transition temperatures of 109−155 °C and decomposition temperatures of ca. 300 °C. The hydrated polymers show protonic conductivity (3.4 × 10-3 S cm-1), which does not decrease at temperatures up to 170 °C.
The intrinsic pK values, as well as the free fractions of sodium and calcium counterions, were determined on salt-free solutions of amidated pectinates and amidated pectates. The apparent pK values were non dependent of the degree of amidation but only to the effective charge density of the pectic polymers and an unique value of 2.9 ± 0.1 was found for the intrinsic pK value. The results obtained by conductimetry and with (sodium and calcium) specific electrodes showed a blockwise distribution of amide and acid groups in amidated pectates and a blockwise distribution of amide groups and a rather statistical distribution of acid groups in amidated pectinates.