Enhanced adsorption/photocatalytic removal of Cu(Ⅱ) from wastewater by a novel magnetic chitosan@ bismuth tungstate coated by silver (MCTS-Ag/BiWO) composite.

An easily separation composite, magnetic chitosan@bismuth tungstate coated by silver (MCTS-Ag/BiWO), was successfully synthesized by the simple hydrothermal method. Moreover, the MCTS-Ag/BiWO demonstrated excellent adsorption/photocatalytic removal of Cu(II) in aqueous solution. Adsorption played a leading role in the synergistic reaction. The catalysts were characterized by fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and scanning electron microscope (SEM). The effects on adsorption of Cu(II) were investigated, which included illumination, pH, and initial concentration. The experimental results showed that the theoretical maximum adsorption capacity of Cu(II) (181.8 mg/g) was achieved under simulated solar light irradiation with the optimal pH value of 6.0, indicating that illumination could enhance the adsorption of Cu(II) by MCTS-Ag/BiWO. Meanwhile, the composite exhibited desirable adsorption ability of Cu(II) after 5 cycles. The copper ion adsorption fitted well with pseudo-second-order kinetic model and its isotherm followed Freundlich model.