Novel type of alginate gel-based adsorbents for heavy metal removal

Various alginate gel-based adsorbents were investigated for the removal of heavy metals: alginate beads, alginate capsules, and alginate gel-coated adsorbent. Of these, alginate capsules showed the greatest Pb2+ uptake capacity of 1560 mg g(-1) of dry sodium alginate, and the alginate gel-coated adsorbent, prepared simply by forming a thin alginate film on an inert matrix, achieved rapid adsorption equilibrium within 10 min. Adsorbed metals were readily removed from the alginate gel-based adsorbents using eluents such as HNO3 and could be reused for up to 10 adsorption-desorption cycles without marked loss of metal uptake capacity. Alginate gel-coated adsorbents could be prepared in a dried state and have great application potential for the removal of heavy metals from contaminated water. (C) 2004 Society of Chemical Industry.