A Method of Metal Removal

Abstract

Abstract Selected non-living, inactivated materials of biological origin, such as algae, fungi, bacteria and their products, have been screened for their metal uptake capacity from solutions. Each biomass type exhibited different performance for metal species tested. The biosorbent performance also varied broadly with pH of the solution used. The biomass of a green alga Halimeda opuntia and a brown alga Sargassum natans have been identified for their extreme potential to concentrate chromium and gold, respectively. The optimum pH was 4-6 for chromium uptake and below 3 for gold uptake. A brown marine alga Ascophyllum nodosum sequestered cobalt well at pH 4.5 outperforming activated carbon and ion exchange resins. The optimum pH for silver uptake by biomass of a red alga Chondris crispus and for arsenic uptake by yeast Saccharomyces cerevisiae covered a broad range of pH 2-6 and pH 4-9, respectively. A red marine alga Palmaria palmata was the most functional biomass in sequestering platinum at pH below 3. The biosorptive uptake of chromium and gold was rather specific. It was not affected by the presence of other cations such as Cu2+, UO22+, Ca2+, Ni2+ or anions such as CO32−. Kinetics of the metal uptake, except for gold, was generally very rapid. Sequestered metals could be eluted from the biomass and the biosorbent material can subsequently be reused many times over. The work demonstrates existing potential of a new group of biosorbent materials of microbial origin which can be effectively applied in a novel process of metal recovery from dilute solutions. The process of biosorption has a commercial potential as documented by several new enterprises currently aggressively entering the field.