Removal of bivalent and trivalent ions by Spirulina platensis biomass: batch experiments and biosorbent characterisation

The removal of cadmium and chromium, at comparable initial molar concentration (1, 2, 4 mM) has been studied employing progressively increasing concentrations of S. platensis dry biomass. The highest yield of Cd removal (≥98%) was obtained with 2 g l−1 of this biosorbent, whereas no more than 77.5% of Cr was removed with 4 g l−1 biomass. The FT-IR analysis evidenced that the ions removal occurs by interaction mainly between metal and carboxylate groups present on the cell wall. Moreover, whereas Cd was also bound with the OH and amide groups, Cr interacted preferentially with OH groups.

Keywords: bivalent ions, trivalent ions, biosorption, functional groups, FT-IR, adsorption, Spirulina platensis biomass, cadmium removal, chromium removal, adsorption, wastewater treatment