Biosynthesis of ZnO/SiO 2 nanocatalyst with palash leaves’ powder for treatment of petroleum refinery effluent

Abstract

This work aims the synthesis and characterization of ZnO/SiO 2 nanocatalyst from plant waste material by green route and application of this ZnO/SiO 2 nanocatalyst for the treatment of petroleum refinery efflu- ent. Butea monosperma (Palash) leaves’ powder was used as reducing and stabilizing agent for synthesis of ZnO/SiO 2 nanocatalyst. Palash leaves contain broad variability of biomolecules which work as reducing and capping agent. In this research work, COD and acenaphthylene which is Polycyclic Aromatic Hydro- carbons (PAH) were degraded by synthesizing ZnO/SiO 2 nanocatalyst under UV-light in an annular photo- catalytic reactor. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), FIELD emission gun-Scanning electron microscopy (FEG-SEM), Energy dispersive X-ray (EDX) and Transmission electron microscopy (TEM) analysis confirmed the formation of ZnO/SiO 2 nanocatalyst. Characterization studies re- vealed that spherical and hexagonal nanoparticles with particle size ranging from 8 ±5 nm to 40 ±5 nm and mean particle with diameter of 20 ±5 nm were synthesized using this method which is stable in the environment. Brunauer, Emmett and Teller (BET) surface area of ZnO/SiO 2 nanocatalyst is found to be 150.25 m 2 /g. Fractional Factorial design was applied to find optimum condition of process parameters and found that optimum percent. Removal of COD (mg/l), and acenaphthylene were achieved at reaction condition of 1 g/L of ZnO/SiO 2 nanocatalyst loading, 30 °C temperature and 4 h reaction time and found that optimum percent removal of COD (mg/l), and acenaphthylene is 75%, and 73% respectively. Various metals, naturally present in palash leaves’ powder, decrease band gap of energy and improve photocat- alytic activity of nanocatalyst.