Biosorptive removal of uranium(Ⅵ) from aqueous solution by Myriophyllum spicatum

摘要

Batch tests were performed to study the U(VI) biosorption process by the nonliving biomass of the aquatic macrophyte Myriophyllum spicatum. Effects of various operational parameters, such as contact time, pH, initial U(VI) concentration, and temperature, were investigated in detail. Results suggested that the U(VI) adsorption capacity increased with increasing initial pH from 1.0 to 7.0, and the best pH was found to be 5.0. Kinetic investigations suggested that adsorption equilibrium can be reached within 80 min and pseudo-second-order kinetic model best characterizes the biosorption behavior. The adsorption thoroughly agreed with the Langmuir isotherm and the maximum adsorption capacity was calculated to be 136.61 mg/g. Changes in free energy and enthalpy derived from the adsorption data revealed that the biosorption of U(VI) onto M. spicatum was spontaneous (Delta G(0) 0), endothermic (Delta H-0 0), and thermodynamically favorable. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy analysis indicated that hydroxyl and amino groups on the algal surface could contribute to the U(VI) biosorption process, in which complexation and ion exchange mechanisms might be involved. In conclusion, M. spicatum biomass could be used as a promising biosorbent to remove U(VI) contamination efficiently with high adsorption capacity and fast adsorption rate.