The Effect of Polar Solutions on the Nanoparticles ZnO Characterization: Experimental Study for Photodegradation of Phenol from Wastewater

Abstract

This study explores phenol removal from industrial wastewater using a UV slurry bubble column reactor with pre-synthesized ZnO nanoparticles. ZnO was prepared via the sol-gel method using three solvents deionized water (CAT-1), ethanol (CAT-2), and glycerol (CAT-3). Zinc oxide nanoparticles were synthesized through the sol-gel method prior to their use in the photocatalytic process. Glycerol led to smaller particles with higher surface area due to its high viscosity and ability to control nucleation. These ZnO particles were then used in a UV slurry bubble column reactor, where UV light excited the ZnO, producing electron-hole pairs. These pairs interacted with water and oxygen to create hydroxyl and superoxide radicals. These radicals attacked phenol molecules, breaking them down into intermediates and finally into CO₂ and H₂O. This degradation followed pseudo-first-order kinetics, and the best performance was recorded with the glycerol-derived ZnO (CAT-3), confirming its suitability for wastewater treatment. CAT-3 calcined at 400°C showed the best surface area and crystallinity. The photocatalytic process achieved over 90% phenol degradation under optimal conditions. ZnO acts as a semiconductor, where UV light excites electrons, generating reactive species that oxidize phenol into harmless by-products. This method provides an efficient, eco-friendly approach to treating industrial wastewater.