Characteristics and mechanism of uranium(VI)adsorption on glutaraldehyde crosslinked humic acid-immobilized sodium alginate porous membrane

Glutaraldehyde crosslinked humic acid-immobilized sodium alginate was used to develop a novel porous composite membrane adsorbent(GA-HA/SA)for the removal of uranium(Ⅵ)ions from uranium-contained wastewater.The physicochemical properties of GA-HA/SA before and after adsorption were investigated by FTIR,SEM and EDX methods.To investigate the effects of experimental parameters on adsorption behavior,batch experiments were performed by changing solution pH,initial concentration of U(Ⅵ)ions,contact time and temperature.The experimental data fit the Langmuir and Dubinin-Radushkevich(D-R)isotherm models well.The adsorption process can be described by pseudo-second-order kinetic model and the correlation coefficient is more than 0.99.The adsorption rate is controlled mainly by intra-particle diffusion.The calculated thermodynamic parameters such as Gibbs free energy change,enthalpy change and entropy change indicate that the adsorption of U(Ⅵ)onto GA-HA/SA is feasible,spontaneous and endothermic in nature.FTIR and mean free energy of adsorption for D-R isotherm show that the adsorption of U(Ⅵ)ions onto GA-HA/SA involves an ion exchange process.