Graphene and bentonite supported ferrites nanocomposites for efficient antibiotic degradation

Abstract

newlineABSTRACT Contamination in water due to pharmaceutical compounds has massive adverse effect on human health. These pharmaceutical products such as antibiotics can cause adversely effect even at very low concentration. Conventional waste water treatment methods are not efficient for the removal of antibiotics. Photocatalytic degradation using metal oxide semiconductors and generate the most powerful oxidizing agent i.e. hydroxyl radicals through illumination with visible light and has been proven to be the most effective purification process of these pollutants. Magnetic ferrites nanoparticles have been intensively investigated due to their unique physical and chemical properties as well as their various applications such as photocatalysis. Magnetic nanomaterials are emerging as an ideal choice to deal with problem of tedious catalyst separation and lower recyclability of metallic photocatalysts after treatment process. newlineIn present study, nano-sized NiFe2O4, MnFe2O4 and ZnFe2O4 (M-Fe2O4) were immobilized onto graphene sand composite (GSC) and bentonite (BT) to report efficient supported photocatalytic system for wastewater treatment. The simple modified hydrothermal method was used to report NiFe2O4, MnFe2O4 and ZnFe2O4 photocatalytic system. Common sugar and river sand were used as precursor for the preparation of GSC. The effective mineralization of antibiotics, oxytetracycline (OTC) and ampicillin (AMP) using NiFe2O4, MnFe2O4 and ZnFe2O4 photocatalyst stacked to graphene sand composite (GSC) and bentonite (BT) was investigated. The morphology and compositional characteristics of synthesized NiFe2O4/GSC, NiFe2O4/BT, MnFe2O4/GSC, MnFe2O4/BT, ZnFe2O4/GSC and ZnFe2O4/BT photocatalysts were investigated using FESEM, TEM, HRTEM, EDX, FTIR, XRD, FT-RAMAN, BET, VSM and UV-Visible reflectance spectral analysis. Magnetic studies revealed superparamagetic behavior of MnFe2O4/GSC, MnFe2O4/BT and ZnFe2O4/GSC, ZnFe2O4/BT and ferromagnetic behavior of NiFe2O4/GSC, NiFe2O4/BT. The optical band gap of NiFe2O4/GSC, NiFe2O4/BT, MnFe2O4/GSC, MnFe2O4/BT, ZnFe2O4/GSC and ZnFe2O4/BT system were 2.41eV, 2.42eV, 2.38eV, 2.42eV, 1.95eV and 1.95eV respectively. Synthesized photocatalytic system exhibited significant photocatalytic activity for mineralization of OTC and AMP under solar light. The adsorption process had newlinexiv newlinesignificant effect on photodegradation of AMP and OTC was described by pseudo second order kinetics. Simultaneous adsorption and degradation process (A+P) had synergetic effect on antibiotic degradation rate. The applicability of power law model indicates the intricacies of mineralization process. During A+P process, both OTC and AMP antibiotics were mineralized to CO2, H2O, NO3- and SO42- ions. The noteworthy recycle efficiency and easier recovery of synthesized photocatalyst was observed for 10 catalytic cycles.