Degradation of pesticide by combined photofenton-ozonation process and study of its synergistic effect

Abstract

This study presents degradation of pesticide, carbaryl, by combined photofenton-ozonation (PFO) process. Experiments

were conducted under pH (3-9), ferrous ion dosage (0-600 mg/l), hydrogen peroxide (0-4 g/l) and ozone dosages (0.12-0.57 g/h) for

optimized reaction conditions of carbaryl degradation. Five experimental sets (UV/Fe²⁺/H₂O₂,UV /O₃, Fe²⁺/H₂O₂, O₃ and UV/Fe²⁺/H₂O₂/O₃) were conducted under optimized conditions to prove synergistic effect. Kinetic study revealed increased rate

constant in combined process (PFO, 0.0194 min^-1) compared to individual process (photofenton, 0.0120 min^-1; ozonation, 0.0112 min^-1). Presence of inorganic ions such as nitrate indicated fragmentation of active pesticide structure. Complete removal of parent

carbaryl and 86% mineralization was achieved at the end of 180 min treatment with combined processes.