Removal of Hg2+ from aqueous solution using alginate gel containing chitosan

Glutaraldehyde-crosslinked alginate gel containing chitosan (AGCC) used for the removal of Hg2+ ions from aqueous solutions. Three bead sizes were obtained and performed to study the uptake equilibrium and kinetics of Hg2+ by AGCC (ca. an hour). The adsorption capacity was found to be independent of adsorbent particle size indicating that sorption occurs in the whole AGCC bead. A high initial rate of Hg2+ uptake was followed by a slower uptake rate suggesting intraparticle diffusion as the rate-limiting step. The rate of Hg2+ uptake increases with decreasing AGCC bead size. AGCC also enhanced the rate and the capacity of Hg2+ adsorption. The maximum Hg2+ adsorption capacity of AGCC was found 667 mg/g, which is over 20 times higher than that of alginate bead. Our results reveal the well-distributed chitosan powders in the alginate gel bead and Hg2+ ions can reach inside the chitosan bead. It indicates the feasibility of using AGCC as metal adsorbent at low pH values, and allows the regeneration of adsorbent. Hg-+(2) ions adsorbed on AGCC bead were desorbed effectively about 95% by H2SO4 at the third cycle. The use of AGCC for the removal of Hg2+ ions from the waste streams appears to be promising. (c) 2007 Wiley Periodicals, Inc.