Chitosan/poly(methacrylic acid) complexes, CS/PMAA, were prepared via dropwise addition of a solution of PMAA to a solution of chitosan in acetic acid 2 wt %. The increase in molecular weight of PMAA inhibited the formation of insoluble complexes, while the increase in ionic strength first favored the formation of the complex followed by inhibiting it at higher concentrations. These observations were related to a description of polyelectrolyte complexation that was strongly dependent on macromolecular dimensions, both in terms of molecular weight and of coil expansion/contraction driven by polyelectrolyte effect.
Removal of chromium(III) from aqueous solutions by chitosan impregnated with a microemulsion was
investigated. The modified chitosan showed a remarkable increase in chromium sorption capacity as
compared to an untreated sample. Dynamic column experiments were performed to study the influence
of pH, concentration, and the presence of others metal ions (copper and nickel) in the chromium solutions.
The adsorption process is pH-dependent, and the amount of Cr(III) retained increases with increasing
heavy metal initial concentration. It can be observed that the best bed efficiency was for copper, followed
by chromium and then nickel. The nature of chromium(III) adsorption equilibrium at different temperatures
(30, 40, and 50 °C) was investigated, and the Freundlich and Langmuir isotherm models were applied to
fit the experimental data. The uptake process obeys the Langmuir isotherm. Following the adsorption step,
the desorption process was carried out using several eluant solutions. The best results were obtained using
strongly acidic solutions as eluants.
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