Degradation of Orange G by Advanced Oxidation Processes

LUCILA DOUMIC; MIRYAN C. CASSANELLO; M. ALEJANDRA AYUDE; PATRICIA M. HAURE

Naantali

Conferencia; Catalysis in Multiphase Reactors CAMURE-8 International Symposium on Multifunctional Reactors ISMR-7; 2011

Nowadays, more than 100,000 dyes are available commercially and used in many industrial processes such as textile, cosmetics, food, pharmaceutical, paper, pulp manufacturing, dyeing of cloth, leather treatment, printing, etc. Global production exceeds 800,000 tons per year and approximately 10% to 15% of this production is discharged into wastewater. The presence of dyes in water is decidedly undesirable since a very small amount, in some cases less than 1 ppm of dye concentration, produces obvious water coloration, may exhibit toxic effects on microbial populations and can be harmful and/or carcinogenic to mammalian animals (Bouasla et al., 2010). As a result, elimination of dyes from industrial effluents before discharge is a major environmental problem. Removal can be accomplished by different chemical and physical processes such as adsorption, coagulation, oxidations by ozone or hypochlorite. However, these methods are expensive and may not eliminate the color completely. Recently, Advanced Oxidation Processes (AOPs) have been used to achieve complete mineralization of recalcitrant compounds. Among them, Fenton's reaction is very appealing because of its simplicity and the low price, availability and small toxicity of its reagents. Fenton's reactions have been among the most studied homogeneous AOPs (Chang and Chern, 2010). The aim of this work is to determine the influence of various parameters on the Fenton degradation of the synthetic dye Orange G (an azo dye) dissolved in water as a test chemical to represent the concerned dye group. Experiments have been carried out in a batch reactor with magnetic stirring, at several moderate temperatures and pH 3. Performance was evaluated by UV/VIS spectrophotometry, total organic carbon (TOC), pH and H2O2 concentration measurements. The reaction has been tested under typical experimental conditions used for Fenton and also promoted by simultaneous continuous and intermittent air circulation and with activated carbon addition. The effect of temperature, air flow, H2O2 concentration and dosification and reaction times on decolorization as well as on mineralization is analyzed. Decolorization of Orange G undergoes faster than mineralization. The presence of air bubbling into the solution definitely enhances the Fenton process and so does the sequential addition of H2O2. References Bouasla, C., Samar, M., Ismail, F. (2010). Degradation of Methyl Violet 6b Dye by the Fenton Process. Desalination, 254, 35-41. Chang, M. W., Chern, J. M. (2010). Decolorization of Peach Red Azo Dye by Fenton Reaction: Initial Rate Analysis. J. Taiwan Inst. of Chem. E., 41, 221–228.