Photocatalytic mineralization of antibiotics using 60%WO3/BiOCl stacked to graphene sand composite and chitosan

Abstract

In this work, effective mineralization of antibiotics, oxytetracycline (OTC) and ampicillin (AMP) using WO3/BiOCl photocatalyst stacked to graphene sand composite (GSC) and chitosan (CT) was investigated. Common sugar and river sand were used as precursor for the preparation of GSC. Modified hydrolysis method was used to prepare WO3/BiOCl photocatalyst with different weight percentage ratios of WO3. 60%WO3/BiOCl displayed highest photocatalytic efficiency for OTC and AMP removal. Furthermore, 60%WO3/BiOCl was immobilized onto GSC and CT to prepare 60%WO3/BiOCl/GSC and 60%WO3/BiOCl/CT nanocomposites. The prepared photocatalysts were characterized using FESEM, TEM, HRTEM, EDX, FTIR, XRD, FT-RAMAN, BET, photoluminescence and UV-Visible reflectance spectral analysis. Both 60%WO3/BiOCl/GSC and 60%WO3/BiOCl/CT displayed significant photocatalytic activity for OTC and AMP removal. The adsorption effect of OTC and AMP photodegradation was also evaluated. The adsorption of OTC and AMP was described by pseudo second order kinetics. Simultaneous adsorption and photocatalysis had synergetic effect on antibiotic degradation. Power law model was applied to understand the complex nature of mineralization process. 60%WO3/BiOCl/GSC and 60%WO3/BiOCl/CT exhibited significant recycle efficiency and easier recovery of photocatalyst for 10 catalytic cycles as compared to 60%WO3/BiOCl. Keywords: WO3/BiOCl, Antibiotics, Supported photocatalysis, Adsorption, Mineralization, Kinetics