DEGRADATION OF 4-NITROPHENOL FROM INDUSTERIAL WASTEWATER BY NANO CATALYTIC OZONATION

Abstract

In this project, a nano catalyst (TiO 2 ) and ozone combined with each other and they were used for the removal of 4-nitrophenol (4NP) in industerial wastewater. The effect of some operational parameters such as initial pH (3-9), the concentration of pollutant (20-80 mg/L), and amount of TiO 2 were investigated. In O 3 /TiO 2 process, the anion radical formed before the production of hydroxyl radical. These results were different from the Ozonation process alone, in which high pH had a positive effect on the degradation of 4NP, because hydroxyl radicals was formed. In ozonation and O 3 /TiO 2 processes, about 89 and 97% of 4NP were degraded respectively, at optimum pH and 60 min of reaction. In catalytic ozonation the degradation rate of 4NP was higher at weak acidic pH conditions (pH=5). The removal of chemical oxygen demand (COD) was increased from 49% (only ozonation) to 74% (O 3 /TiO 2 ) at 90 min of reaction. The kinetic of degradation was pseudo-first-order and degradation and mineralization of 4NP were estimated by HPLC and COD tests, respectively. Ke ywords: Chemical Oxygen demand (COD); Degradation; Iindusterial wastewater; TiO 2 nano catalyst; 4-Nitrophenol (4NP)