The influence of the degree of cross-linking on the adsorption properties of chitosan beads.
The influence of the degree of cross-linking (DCL) on chitosan beads was studied. Chitosan was prepared from the exoskeleton of Cape rock-lobsters, collected from the surroundings of Cape Town, South Africa. The chitosan beads were characterized; the beads water contents and pKa varied in the range of 90-96% and 4.3-6.0, respectively, and were found to decrease with increasing DCL (0.0-34.0%). A pH-model, which described the reversibility of the metal adsorbed onto the beads, was used to predict the equilibrium properties of copper adsorption onto the cross-linked beads. The model accounts for the effect of pH and the important model parameters, the equilibrium adsorption constant (Kads) and to a lesser extent the adsorbent adsorption capacity (qmax) showed to decrease with the DCL. The adsorbent capacity and the adsorption constant were determined as 3.8-5.0mmol/g chitosan and (9-90)x10(-4), respectively. The adsorption kinetics could be described using a shrinking core model and the effective diffusion coefficient (Deff) was determined as (8.0-25.8)x10(-11)m2/s. It was found that Deff decreases with the DCL mainly due to the decreased in water content of the beads at high DCL.
Osifo
Peter O
PO
Department of Chemical Engineering, Vaal University of Technology, Private Bag X021, Vanderbijlpark, Guateng 1900, South Africa. petero@vut.ac.za
Webster
Athena
A
van der Merwe
Hein
H
Neomagus
Hein W J P
HW
van der Gun
Marius A
MA
Grant
David M
DM
D000327:Adsorption; D048271:Chitosan / Q000737:chemistry*; D003300:Copper / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D007700:Kinetics
D003300:Copper; D048271:Chitosan