Photochemically Enhanced Fenton Reaction Used In The Degradation Of Water-soluble Dyes

Treatment of printing and dyeing wastewater has attracted increasing attention of researchers in recent years. Because the composites of printing and dyeing waste water are complex, including a large quantity of dyes and assistants, main pollutants of it are SS, COD, heat retention, color, acid and alkali. Bottleneck of its treatment is how to remove the color, which cannot be treated easily through conventional technologies.Advanced Oxidation Technology is a promising technology for the removal of toxic organic and inorganic contaminants from water. In this research, one of the AOTs--photochemically enhanced Fenton Reaction is applied for the degradation ofRhodamine B and Eosin Y. The impacts of operational parameters are considered and investigated, namely: light source, initial pH value, initial dye concentration, dosage of Fe2+, dosage of H2O2 and addition of iron scraps. Through a series of controlled experiments, simplified kinetic equations for the degradation of Rhodamine B and Eosin Y by sunlight enhanced Fenton oxidation processes are derived, within which, concentration of the dye, concentration of hydrogen peroxide and concentration of Fe2+ are the variables. Four kind of real dyeing wastewater and real photocopying wastewater are treated by sunlight enhanced Fenton oxidation in this study and experimental results have been evaluated.Conclusions of this study are listed below:Fenton's reagent is an appropriate method to efficiently remove Rhodamine B from aqueous solutions. Sunlight and high-pressure mercy lamp can both enhance this process. pH=3.5 is the optimized initial pH value. For the treatment of 100mg/L Rhodamine B solution, effective dosage of 30%H2O2 is in the range of 2.4-5.0ml/L and in this range, the more hydrogen peroxide the faster degradation rate. Optimized dosage of 18mmol/L Fe2+ solution is lO.Oml/L. Kinetic equation for the degradation of Rhodamine B by sunlight enhanced Fenton oxidation process is V=5 10-9 [Dye]1.2845 X [Fe2+]0.3660X [H2O2]0.9204.( The initial pH value is 3.5).Eosin Y can be removed efficiently from aqueous solutions by Fenton's reagent. Sunlight and high-pressure mercy lamp can both enhance this process and sunlight has a better effect than the latter. pH=3.5 is the optimized initial pH value. In the treatment of 100mg/L Eosin Y water solution, if the initial pH value is adjusted to 3.5, dosage of 18mmol/L Fe2+ solution is 5.0ml, dosage of 30% hydrogen peroxide is 2.5ml and underthe sunlight in July, COD removal can attain 92.7% and more than 99.9% dye can be degraded. Kinetic equation for the degradation of Eosin Y by sunlight enhanced Fenton oxidation process is V=0. 000249 X [Dye] "-7949X [Fe2T'379X [H202]' 259?(The initial pH value is 3.5).It is verified that sunlight enhanced Fenton oxidation process with the addition of iron scraps can be applied in the pretreatment and post processing of this four kind of real wastewater with a considerable color removal and COD removal. After being diluted 2 and 4 times respectively and treated by this method, the color of 2G Khaki dyeing wastewater and Vat Olive Green B dyeing wastewater can almost attain the discharge standard.