A review of potentially low-cost sorbents for heavy metals

The use of low-cost sorbents has been investigated as a replacement for current costly methods of removing heavy metals from solution. Natural materials or waste products from certain industries with a high capacity for heavy metals can be obtained, employed, and disposed of with little cost. Modification of the sorbents can also improve adsorption capacity. In this review, an extensive list of sorbent literature has been compiled to provide a summary of available information on a wide range of potentially low-cost sorbents, including bark, chitosan, xanthate, zeolite, clay, peat moss, seaweed, dead biomass, and others. Some of the highest adsorption capacities reported for cadmium, chromium, lead and mercury are: 1587 mg Pb/g lignin, 796 mg Pb/g chitosan, 1123 mg Hg/g chitosan, 1000 mg Hg/g CPEI cotton, 92 mg Cr(III)/g chitosan, 76 mg Cr(III)/g peat, 558 mg Cd/g chitosan, and 215 mg Cd/g seaweed.