Nanofibrous polydopamine complex membranes for adsorption of Lanthanum (III) ions

A novel polydopamine (PDA) membrane prepared by coating PDA on nanofibrous mats was used for adsorption of La (III) ions, where the nanofibrous mats were fabricated with blended solution of polyacrylonitrile (PAN) and polysulfone (PSF) in N,N'-dimethyl acetamide by electrospinning. The morphology of nanofibers observed by field emission scanning electron microscopy showed that heterogeneous structural protuberances existed on the surface of nanofibers due to microphase separation between the two incompatible polymers. This scabrous heterogeneous structure of fiber surface was beneficial to PDA adhesion and resulted in the PDA complex membranes with high specific surface area. The as-prepared PDA membranes were subject to adsorption of La (III) ions in aqueous solution and could be desorbed and regenerated easily. The effects of initial solution concentration, pH, and contact time on adsorption of La (III) ions have been investigated in detail. It was shown that the maximum equilibrium uptake capacity of La (III) on PDA membrane was 59.5. mg/g (0.43. mmol/g) and the experimental data was well fitted to Langmuir isotherm equation. This study provided a novel route to pre-concentrate or separate La (III) in separation processes of hydrometallurgy.