Bioadsorption studies of arsenate from aqueous solutions using chitosan

摘要

This study proposed the use of chitosan (biopolymer with a deacetylation degree of 85%) to remove arsenate [As(V)] ions from aqueous solutions. Batch adsorption experiments were carried out as a function of pH, contact time, initial concentration of the adsorbate, adsorbent dosage, and co-anions were evaluated. Maximum adsorption (82%) has taken place at pH 5.0,while equilibrium was achieved in 60 min. at temperature 25°C, with adsorbent dose (1 mg/g), initial concentration 1 g/L As(V), and shaking speed 200 rpm. The presence of coexisting anions has a negative effect on As(V) adsorption. The equilibrium adsorption data were fitted reasonably well for the Langmuir adsorption isotherm and showing maximum As(V) adsorption capacity of chitosan was 123.7 mg/g. Kinetic study reveals that adsorption of As(V) is fast and follows pseudo-second-order kinetics. The results reveals that chitosan biopolymer (with deacetylation degree of 85%) can be an effective adsorbent for removing As(V) from groundwater.