Enhanced Pb(II) removal by green alga Neochloris oleoabundans cultivated in high dissolved inorganic carbon cultures

Abstract

The objective of this study was to test a novel strategy for enhancing the Pb(II) adsorption capacity of green alga Neochloris oleoabundans by manipulating the concentration of dissolve inorganic carbon (DIC) in cultivation medium. It was demonstrated that the optimized DIC concentration could increase the lead biosorption capacity of cells by up to 2.4 times. The adsorption was monolayer Langmuir adsorption occurring at cell surface and the adsorption happened rapidly with equilibrium established within 5 min. The negative zeta potentials of the biomass increased sharply with the increase of DIC concentration in medium, indicating an increase of charges on cell surface, which seems to be responsible for the increase of Pb(II) adsorption capacity. FTIR spectra illustrated the presence of carbonyl, carboxyl, amide, and phosphate groups that might serve as the sites of adsorption at cell surface. There are evidences suggesting that CO containing ionisable functional groups such as carboxyl played a major role in the adsorption enhancement of DIC in media.