Sonocatalytic degradation of direct blue dye using semiconductor nanocatalyst

Abstract

The toxic pollutants present in water should be treated by advanced oxidation processes (AOP). This investigation deals with study of sonocatalytic degradation of the prepared zinc oxide nanorods (ZnONR) under ultrasonic (US) irradiation for the degradation of Direct blue (DB71) dye molecule. ZnONR has been prepared by sol-gel method using zinc acetate and ammonia. The prepared ZnONR have been characterized using FT-IR, XRD, FE-SEM, HR-TEM, EDAX, AFM and BET techniques and found that the prepared catalyst is highly crystalline with hexagonal structured nano rods with Wurtzite crystal phase. In-situ generation of the OH. radicals has been analyzed by EPR technique. Preliminary experiments are conducted such as effects of pH, catalyst loading, dye concentration and effect of energy input to optimize suitable experimental conditions. Kinetics of sonocatalytic degradation of dye molecules have also been carried out and the reaction followed pseudo first-order kinetics. The interference of electrolytes on the degradation of dye molecules has also been carried out. Degradation of the dye molecules are examined by UV-Visible absorption, COD and TOC measurements. The by-products formation of the degraded samples has been analyzed by ESI-MS+ technique. The reusability of the catalyst for its efficiency and the degradation of real dye house effluents have also been tested