Decolourisation of aqueous dyes by sequential oxidation treatment with ozone and Fenton's reagent

Abstract

Combined oxidation with ozone and Fenton's reagent (`Fentozone' process) for decolourisation of aqueous dyes was studied and compared with traditional Fenton's reagent. Although thè Fentozone' process was found to be effective at a wide range of pH values, the maximum colour removal was achieved at pH 4. The effect of pre-ozonation on colour removal ef®ciency of aqueous dyestuffs in the subsequent treatment with Fenton's reagent was investigated. The reaction kinetics using water-soluble acid and reactive dyes were also studied. Our experimental results show that preozonation can considerably accelerate decomposition of dyestuffs in the subsequent treatment with Fenton's reagent. Different concentrations of ferrous sulfate were used to investigate their in¯uences on the removal of colour. The rate of reaction increased with increasing doses of ferrous sulfate.

Decolourization of Industrial Effluents – Available Methods and Emerging Technologies – A Review

“…Decolouration of aqueous dyes was observed by ozone and Fenton's reagent (''Fentozone'') and was compared with traditional Fenton's reagent. Colour removal was found to be 89% at a pH of 4 (Hassan and Hawkyard 2002). A comparision of different oxidation processes for the decolourization of azo dye in waters was presented by Neamtu et al (2004).…”

Color, TOC and AOX removals from pulp mill effluent by advanced oxidation processes: A comparative study

“…In order to meet increasingly stringent discharge limits, pulp mills are forced to adopt technologically advanced treatment systems. Organic compounds such as chlorophenols are not fully degraded by biological processes which require advanced oxidation after biological treatment to reduce refractory organics and color of the pulp mill wastewater [4,5,[7][8][9][10][13][14][15][16][17][18][19].…”

“…Different oxidation methods such as hydrogen peroxide, Fenton's reagent, direct photolysis with UV, hydrogen peroxide/UV, Photo-Fenton, ozonation and peroxone treatments were used. Effect of operating conditions such as pH (3)(4)(5)(6)(7)(8)(9)(10)(11), H 2 O 2 (5-100 mM), Fe 2+ (1-5 mM) and ozone doses (4.7-11.9 g/h) on color, TOC and AOX removals were investigated for each oxidation method tested.…”

On-site treatment of textile yarn dyeing effluents using an integrated biological–chemical oxidation process

“…The complexity of textile effluents makes it difficult to treat them economically as they contain chelating agents, surfactants, thickeners, enzymes, detergents, grease, dirt, sizing agents, solvents, different additives, oxidizing and reducing agents, heavy metals and residual dyes (Arafat 2007;Badani et al 2005;Buitron et al 2004;Haroun and Idris 2009;Hassan and Hawkyard 2002;Lau and Ismail 2009;Nandy et al 2005). A large fraction of chemicals includes toxicants, inhibitory compounds and recalcitrant organics with complex structures, such as aromatic rings, resistant to biodegradation (Grekova-Vasileva and Topalova 2009).…”