Photocatalytic Degradation of Nitrobenzene and Azo Dye Using Zinc Oxide Nanoparticles Prepared by Electrochemical Method

Abstract

Photocatalytic degradation of nitrobenzene (NB) and an azo dye (namely azophloxine) was carried out using zinc oxide (ZnO) nanoparticles which were prepared by electrochemical method using zinc electrodes in aqueous oxalic acid solution. Taguchi methodology was applied for studying the effects of four experimental parameters namely catalyst dosage (g/l), time of reaction (h), pH and H₂O₂ dose. Degradation efficiency of NB was found to increase with an increase in H₂O₂concentration and decrease in catalyst dosage and pH. Maximum NB degradation efficiency of 98% was observed at catalyst dosage=1 g/l, pH=3, H₂O₂ to C₆H₅NO₂ ratio of 7 mol/mol after 5 h of treatment. Similarly, maximum dye degradation efficiency of 58% and color removal efficiency of 78% was observed at catalyst dosage=1.25 g/l, pH=4, H₂O₂concentration of 8 mmol/l in 5 h. Overall, prepared ZnO nanoparticles performed better for NB degradation in comparison to azo dye degradation.