Efficient removal of Cr (VI) by magnetic and recyclable calcined CoFe-LDH/g-C3N4 via the synergy of adsorption and photocatalysis under visible light

Magnetic and recyclable calcined CoFe-LDH/g-C 3 N 4 catalyst was prepared by co-precipitation and calcination method, and used as a multifunctional material to remove hexavalent chromium (VI) via the synergistic effect of adsorption and photocatalysis. The calcined CoFe-LDH provide surface adsorption in the composite, which could lead to the adsorption of Cr (VI) with high adsorption capacity and fast speed. The g-C 3 N 4 nanosheets have high photocatalytic activity in situ for the composite to reduce Cr (VI) into Cr (III). The results demonstrated that 60% Cr (VI) (50 mg L −1 ) can be adsorbed by the nanocomposite in 10 min and the removal efficiency of Cr (VI) reached 100% in 90 min under visible light irradiation by adsorption and photocatalysis. In addition, the calcined CoFe-LDH/g-C 3 N 4 exhibits a mostly pore size about 2.58 nm, large specific surface area (101.61 m 2  g −1 ) with the high structural stability and saturation magnetization (23.06 emu g −1 ), hence, could be easily recycled for ten subsequent runs with little activity loss.