Removal of silver(I) from aqueous solutions by chitosan/bamboo charcoal composite beads

Chitosan/bamboo charcoal composites were prepared by blending chitosan with bamboo charcoal and forming composite beads. The composites were used as silver ion (Ag+) adsorbents. Batch adsorption experiments were performed as a function contact time, bamboo charcoal concentration, pH value, and adsorbent dosage level. Equilibrium contact time of 180 min was achieved by chitosan and composite adsorbents. Composite adsorbent had the highest adsorption efficiency when the bamboo charcoal content was 50% of chitosan weight. The maximum Ag+ removal was obtained at the initial pH value of 6. The optimum adsorbent dosage for Ag+ removal was 0.4 g/L. Under above optimal conditions the maximum Ag+ removal was 100%. The adsorption isotherm of chitosan/bamboo charcoal composite beads agreed well with the Langmuir model. The maximum adsorption capacity was 52.91 mg/g. The Ag+ desorption of composite bead was 31.76%. SEM/EDX images confirm that after adsorption the Ag+ was dispersed onto the composite bead surface. This study demonstrated that the chitosan/bamboo charcoal composite can effectively remove Ag+ from aqueous solution and simply with low cost.