Study on the adsorption of Ca 2+, Cd 2+ and Pb 2+ by magnetic Fe 3O 4 yeast treated with EDTA dianhydride

Abstract

Magnetic Fe 3O 4 baker's yeast biomass (FB) was prepared by combining baker's yeast biomass and nano-Fe 3O 4 using glutaraldehyde as a cross-link agent, and was chemically treated with ethylenediaminetetraacetic dianhydride (EDTAD). The EDTAD-treated magnetic Fe 3O 4 baker's yeast biomass (EFB) was investigated by Fourier transform infrared spectroscopy (FTIR), potentiometric titration, zeta potential, and magnetic response analysis. The results revealed that the EFB possessed not only the super-paramagnetic characteristic of nano-Fe 3O 4, but its surface also had plenty of carboxyl and amino groups introduced by the EDTA molecules. The adsorption properties of EFB for Pb 2+, Cd 2+, and Ca 2+ ions were also evaluated. The results showed that the uptakes of EFB for the three metal ions were higher than that of FB, and the adsorption capability of Pb 2+, Cd 2+, and Ca 2+ ions increased with an increase in pH. The adsorption process was followed by the pseudo-second-order kinetic model and Langmuir isotherm equation. The maximum adsorption capacities of 99.26 mg/g for Pb 2+ at pH 5.5, 48.70 mg/g for Cd 2+ at pH 6.0, and 33.46 mg/g for Ca 2+ at pH 6.0 were observed at 30 °C. The regeneration experiments showed that the EFB could be successfully reused.