Lipid-extraction algal biomass for biosorption of bivalent lead and cadmium ions: Kinetics and isotherm

Abstract

Residual algal biomass, which is the by-product of the extraction of value-added products such as lipids, proteins, pigments and antioxidants, represent a potentially massive and inexpensive source of biosorbents. The biosorption of heavy metal Pb(II) and Cd(II) by the residual biomass of Chlorella vulgaris after lipid extraction was investigated under varied conditions including pH, contact time and initial heavy metal concentration. That of the wet and dried biomasses of C. vulgaris were also studied for comparison. Biosorption plateaus were achieved within 10 min for Pb(II) and 30 min for Cd(II). The Pb(II) biosorption capacities of by residual, wet, and dried biomass were 262.29, 114.85 and 82.81 mg/g, respectively, and that of Cd(II) were 55.13, 33.21, and 21.41 mg/g, respectively. The biosorption capacities of the residual biomass for Pb(II) and Cd(II) were 3.18 and 2.58-fold of that of dried biomass, which can be attributed primarily to the increased specific surface area.