Biosorption of cadmium by a lipid extraction residue of lipid-rich microalgae

The present study investigates the performances and mechanisms of biosorption of cadmium (Cd) ions using a lipid extraction residue from three strains of lipid production microalgae. The adsorption performance was determined by batch biosorption experiments and kinetic modeling. The algae cell in the whole growth period and lipid extraction residue both exhibited desirable adsorption performance. The lipid extraction residue from the strain of Coelastrum sp. PTE-15 had the highest capacity of Cd sorption, which was 32.8 mg g^-1. FTIR data suggested that the functional groups acting as binding sites on the microalgae surface which participate in biosorption were carboxylic, hydroxyl, and amino. The biosorption properties and maximum adsorption capacity of the lipid extraction residue from three microalgal strains were determined by equilibrium modeling. The adsorption process followed the Langmuir isotherm model with a high value of correlation coefficients (≥0.99) and biosorption capacity being estimated to be 36.1 mg g^-1.