Fenton and Electro-Fenton Methods for Oxidation of H-Acid and Reactive Black 5

• Published in: Journal of environmental engineering (New York, N.Y.) N.Y.), 2006-03, Vol.132 (3), p.367-376
• Main Authors: Rao, N. N, Bose, Gaurav, Khare, Pradnya, Kaul, S. N
• Format: Article
• Language: English
• Subjects: Applied sciences; Chemical oxygen demand; Exact sciences and technology; General purification processes; hydrogen peroxide; Iron; Other industrial wastes. Sewage sludge; Oxidation; Pollution; Q1; TECHNICAL PAPERS; Wastes; Wastewaters; Water treatment and pollution
• ISSN: 0733-9372; 1943-7870
• DOI: 10.1061/(ASCE)0733-9372(2006)132:3(367)

Oxidative treatment of H-acid (HA) and Reactive Black 5 (RB5) using Fenton reagent ( Fe2+ ∕ H2 O2 ) and the electro-Fenton (EF) method is reported. Optimization of doses of ferrous iron and hydrogen peroxide was carried out in each case using HA; and the oxidation of RB5 was also carried out under the optimized conditions. Approximately 71% chemical oxygen demand (COD) was removed in 2 h using the conventional Fenton method at optimized doses: Fe2+ =0.3 g∕L (5.37 mM), H2 O2 =6 mL∕L (53.0 mM), H2 O2 ∕ Fe2+ =10 . In contrast, more than 92% COD was removed in 15 min using the EF method with an optimized Fe2+ dose of 0.130 g∕L (2.34 mM) and 8 ml∕L (70.6 mM) of H2 O2 . The pseudo-first-order rate constants (k) for the Fenton reagent and EF method were 0.054 and 0.38 min−1 . The COD removal through the EF method was seven times faster. The calculated energy requirement of the EF method was 0.82 kg COD∕kW∙h at the minimum applied current (0.25 A) when approximately 92.5% COD was removed. In the case of RB5, about 67 and 87% COD was removed under optimized Fenton and electro-Fenton conditions, respectively. The higher efficiency of the EF method was attributed to incremental addition of Fe2+ and accompanying higher H2 O2 ∕ Fe2+ molar ratio. The results are discussed in the light of the mechanism for Fenton’s oxidation.