Details
Original language | English |
---|---|
Pages (from-to) | 329-339 |
Number of pages | 11 |
Journal | Clay minerals |
Volume | 42 |
Issue number | 3 |
Publication status | Published - Sept 2007 |
Abstract
Adsorption of the polycation chitosan on montmorillonite was studied at different pH values from 4.5 to 6.5 and at temperatures of 25, 50 and 75°C. The amount of chitosan adsorbed increased with temperature, indicating that temperature is a decisive factor. At pH 5.0 and 25°C the amount adsorbed was 1.18 molc kg-1, whereas it was 1.5 times higher (1.79 molc kg-1) at 75°C. The uptake of chitosan increased significantly at higher pH. This can be attributed to the decrease in the degree of protonation. Surface charge and X-ray diffraction measurements indicate that most of the chitosan is adsorbed in the interlayer, where mono- and bilayer structures are formed. The kinetics of chitosan adsorption also depend on temperature and pH. At ≥ 50°C, the adsorption mechanism of chitosan on montmorillonite is closest to the intraparticle diffusion model, whereas at lower temperature (25°C) the adsorption process is closer to the pseudo-second order model. The pH of the solution affects the protonation degree of chitosan and the mode of adsorption on montmorillonite, but not the adsorption rate. For chitosan-montmorillonite prepared at pH 5.0 and 75°C, the effective anion exchange capacity (AEC) was found to be 80% (0.36 molc kg-1) of the calculated value. The relatively large AEC and the location of most of the anion exchange sites in the interlayer make chitosan-montmorillonite an interesting prospect as an adsorbent for water-purification procedures.
Keywords
- Adsorption kinetics, Anion exchange capacity, Chitosan, Montmorillonite, Organo-clay mineral
ASJC Scopus subject areas
- Earth and Planetary Sciences(all)
- Geochemistry and Petrology
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In: Clay minerals, Vol. 42, No. 3, 09.2007, p. 329-339.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Polycation adsorption on montmorillonite
T2 - pH and T as decisive factors for the kinetics and mode of chitosan adsorption
AU - An, J. H.
AU - Dultz, S.
N1 - Copyright: Copyright 2008 Elsevier B.V., All rights reserved.
PY - 2007/9
Y1 - 2007/9
N2 - Adsorption of the polycation chitosan on montmorillonite was studied at different pH values from 4.5 to 6.5 and at temperatures of 25, 50 and 75°C. The amount of chitosan adsorbed increased with temperature, indicating that temperature is a decisive factor. At pH 5.0 and 25°C the amount adsorbed was 1.18 molc kg-1, whereas it was 1.5 times higher (1.79 molc kg-1) at 75°C. The uptake of chitosan increased significantly at higher pH. This can be attributed to the decrease in the degree of protonation. Surface charge and X-ray diffraction measurements indicate that most of the chitosan is adsorbed in the interlayer, where mono- and bilayer structures are formed. The kinetics of chitosan adsorption also depend on temperature and pH. At ≥ 50°C, the adsorption mechanism of chitosan on montmorillonite is closest to the intraparticle diffusion model, whereas at lower temperature (25°C) the adsorption process is closer to the pseudo-second order model. The pH of the solution affects the protonation degree of chitosan and the mode of adsorption on montmorillonite, but not the adsorption rate. For chitosan-montmorillonite prepared at pH 5.0 and 75°C, the effective anion exchange capacity (AEC) was found to be 80% (0.36 molc kg-1) of the calculated value. The relatively large AEC and the location of most of the anion exchange sites in the interlayer make chitosan-montmorillonite an interesting prospect as an adsorbent for water-purification procedures.
AB - Adsorption of the polycation chitosan on montmorillonite was studied at different pH values from 4.5 to 6.5 and at temperatures of 25, 50 and 75°C. The amount of chitosan adsorbed increased with temperature, indicating that temperature is a decisive factor. At pH 5.0 and 25°C the amount adsorbed was 1.18 molc kg-1, whereas it was 1.5 times higher (1.79 molc kg-1) at 75°C. The uptake of chitosan increased significantly at higher pH. This can be attributed to the decrease in the degree of protonation. Surface charge and X-ray diffraction measurements indicate that most of the chitosan is adsorbed in the interlayer, where mono- and bilayer structures are formed. The kinetics of chitosan adsorption also depend on temperature and pH. At ≥ 50°C, the adsorption mechanism of chitosan on montmorillonite is closest to the intraparticle diffusion model, whereas at lower temperature (25°C) the adsorption process is closer to the pseudo-second order model. The pH of the solution affects the protonation degree of chitosan and the mode of adsorption on montmorillonite, but not the adsorption rate. For chitosan-montmorillonite prepared at pH 5.0 and 75°C, the effective anion exchange capacity (AEC) was found to be 80% (0.36 molc kg-1) of the calculated value. The relatively large AEC and the location of most of the anion exchange sites in the interlayer make chitosan-montmorillonite an interesting prospect as an adsorbent for water-purification procedures.
KW - Adsorption kinetics
KW - Anion exchange capacity
KW - Chitosan
KW - Montmorillonite
KW - Organo-clay mineral
UR - http://www.scopus.com/inward/record.url?scp=36049017452&partnerID=8YFLogxK
U2 - 10.1180/claymin.2007.042.3.06
DO - 10.1180/claymin.2007.042.3.06
M3 - Article
AN - SCOPUS:36049017452
VL - 42
SP - 329
EP - 339
JO - Clay minerals
JF - Clay minerals
SN - 0009-8558
IS - 3
ER -