Study on biosorption characteristics of spirulina to rare earth ytterbium ions in simulated mine wastewater

Spirulina was obtained from Zarrouk culture solution and was used as a biomass adsorbent to study the adsorption performance of rare earth cerium ions in simulated mine wastewater. By the means of single channel sequence scanning inductively coupled plasma atomic emission spectrometric(ICP-AES), scanning electron microscope (SEM), fourier transform infrared spectrometer (FTIR), X-ray photoelectron spectroscopy (XPS), the structure and adsorption properties of spirulina was studied. The adsorption kinetics and thermodynamic laws were discussed from the adoption of Freundlich, Langmuir, Redlich-Peterso, Dubin-Radushkevich isothermal adsorption model and pseudo-first-order, pseudo-second-order, elovich equation and intra-particle diffusion model, which can be expected to understand the mechanism of the adsorption process. The adsorption results suggest that the removal rate and the desorption rate of Yb³⁺ from simulated mine wastewater can reach 77 % and 92.3 % respectively when pH of the treated liquid was 5, dosage of spirulina 2.0 g/L, initial concentration of ytterbium ions 100 mg/L and adsorption time 60 min. In this case, the data indicate that the adsorption rate of spirulina was fast and the adsorption effect was ideal. The adsorption kinetics was well accorded with pseudo-second-order kinetic model (R²>0.99). And the adsorption process was mainly controlled by chemical adsorption. The adsorption isotherm was well simulated by Langmuir equation (R²>0.99). The adsorption of Yb³⁺ from simulated mine wastewater by spirulina was a spontaneous endothermic process.