Characteristics of anionic metal species biosorption with waste crab shells

Anionic metal complexes are very effectively bound by biomass types containing an abundance of amine groups. Readily available chitinous materials such as acid-washed Ucides shells (AWUS) sorbed well anionic gold-cyanide (Au(CN)(2)(-)), selenate (SeO(4)(2-)), chromate (CrO(4)(2-)) and vanadate (VO(4)(3-)) at low pH. Equilibrium biosorption uptakes by AWUS were up to 0.17 mmol Au/g AWUS (pH 3.4), 0.15 mmol Se/g (pH 3.0), 0.54 mmol Cr/g (pH 2.0) and 0.79 mmol V/g (pH 2.5). An increased ionic strength (IS) suppressed the primary anion uptake as chloride ions competed for biosorbent protonated sites and higher IS reduced the activity of ions in solution. The biosorption mechanism was suspected to involve electrostatic attraction. (C) 2003 Elsevier B.V. All rights reserved.