Calcined layered double hydroxides/reduced graphene oxide composites with improved photocatalytic degradation of paracetamol and efficient oxidation-adsorption of As(III)

The coexistence of pharmaceuticals and arsenic in natural water may exhibit a synergistic toxic effect on humans or animals. Therefore, efficient simultaneous removal of pharmaceuticals (paracetamol as a target pollutant) and arsenic from water has received increasing attention. In this study, the novel calcined ZnFe-layered double hydroxides/reduced graphene oxide (ZnFe-CLDH/RGO) composites are fabricated via a hydrothermal-calcination method. The obtained ZnFe-CLDH/RGO composites exhibit significantly improved photocatalytic performance toward degradation of paracetamol as compared to the pristine ZnFe-CLDH. The photocatalytic activity of the screened ZnFe-CLDH/RGO30 material for paracetamol degradation is about 3.5 times that of ZnFe-CLDH. The improved photocatalytic activity could be attributed to the RGO, which could lead to increased pollutant adsorption capacity and enhanced charge separation efficiency. The magnetic ZnFe-CLDH/RGO composite also shows excellent stability and reusability as a promising photocatalyst. For As(III) removal, the ZnFe-CLDH/RGO composite displays better removal efficiency in the light than in the dark. It should be ascribed to the synergy of photocatalytic oxidation of As(III) to less toxic As(V) and the accompanying arsenic adsorption. Interestingly, our study indicates that the paracetamol degradation in the mixed system of paracetamol/As(III) is more efficient than that in the single system of paracetamol. Meanwhile, arsenic can be also efficiently removed from the water samples with coexistent paracetamol and As(III) species. This work may provide a promising composite for the efficient simultaneous elimination of water environmental inorganic anions and organic pollutants.