Effect of phosphate in medium on cell growth and Cu(II) biosorption by green alga Neochloris oleoabundans

Abstract

Green alga Neochloris oleoabundans cultivated in medium of varied phosphate (K2HPO4) concentration was investigated as the biosorbent for Cu(II) removal from aqueous solutions. The highest biosorption capacity of 180.19 mg-Cu/g-biomass was achieved with biomass grown in medium containing 300 mg/L K2HPO4, which was 2.4 and 2.3 times of that of the biomasses grown in media containing 100 and 500 mg/L K2HPO4, respectively. The Cu(II) biosorption was fast with equilibrium established within 10 min of contact time and the kinetics was characterized as pseudo-second order. A modified Langmuir isotherm model is proposed to account for the inhibition of Cu(II) biosorption by the cell aggregation induced by Cu(II). Furthermore, it was shown that the Cu(II)-induced cell aggregation could be explored to enhance the sedimentation of biomasses to facilitate biomass recovery after Cu(II) adsorption.