Advanced oxidation of cork-processing wastewater using Fenton's reagent:: kinetics and stoichiometry

This work evaluates Fenton oxidation for the removal of organic matter (COD) from cork-processing wastewater. The experimental variables studied were the dosages of iron salts and hydrogen peroxide. The COD removal ranged from 17% to 79%, depending on the reagent dose, and the stoichiometric reaction coefficient varied from 0.08 to 0.43 g COD (g H2O2)(-1) (which implies an efficiency in the use of hydrogen peroxide varying from 17% to 92%). In a study of the process kinetics, based on the initial rates method, the COD elimination rate was maximum when the molar ratio [H2O2](o):[Fe2+](o) was equal to 10. Under these experimental conditions, the initial oxidation rate was 50.5 mg COD dm(-3) s(-1) with a rate of consumption of hydrogen peroxide of 140 mg H2O2 dm(-3) s(-1), implying an efficiency in the use of the hydrogen peroxide at the initial time of 77%. The total amount of organic matter removed by Fenton oxidation was increased by spreading the H2O2 and ferrous salt reagent over several fractions by 15% for two-fractions and by 21% for three-fractions. (C) 2004 Society of Chemical Industry.