Statistical Evaluation of UV/TiO2/H2O2 and Fe~(2+)/H2O2 Process for the Treatment of Coloured Wastewater; A Comparative Study

摘要

In this work, two types of advanced oxidation processes; photocatalytic oxidation, UV/TiO2/H2O2 and classic Fenton oxidation, Fe~(2+)/H2O2, have been applied for the treatment of a model wastewater containing reactive azo dyes, C.I. Reactive Violet 2 (RV2) and C.I. Reactive Yellow 3 (RY3). In order to evaluate the effect of the initial concentration of catalysts,γ(TiO2) or [Fe~(2+)], initial concentration of oxidant, [H2O2] or the initial oxidant/catalyst mole ratio [H2O2]/[Fe~(2+)] and pH on apparent mineralization and decolourization rates, a response surface method (RSM) D-optimal design was used. Mineralization was described by pseudo-first-order kinetics with the highest observed rate constants; k_(m,UV)= 0.0065 min~(-1) in the case of UV/TiO2/H2O2 process and k_(m,F)= 0.0213 min~(-1) in the case of Fenton process. A kinetic model describing decolourization on wavelengths of maximum absorbance for studied dyes, λ_(maxRY2) 550 nm, and λ_(maxRY3) 3 385 nm, was composed of two first-order in-series reactions with corresponding decolourization rates. The effects of each factor on the efficiency of the applied processes were found to be significant.