Experimental Study On Treating The Cationic Dye Wastewater By Electro-catalytic Oxidation

The cationic dye’s name comes from his molecule with a quaternary ammonium cation.Along with the growth demand of polyacrylonitrile fiber in our country, a good hair color and fastness properties make cationic dye a wide range of applications in the printing and dyeing industry.The generation of dyeing wastewater after using the cationic dye to dye,his wastewater has complex component, high concentrations of CODcr, high salt content, chroma up to tens of thousands of times or hundreds of thousands of times, poor biodegradability characteristics and so on.Therefore,It’s hard to degradation by a single traditional process,but the advanced oxidation technology such as membrane separation, photocatalytic technology has the high cost.This topic through the static simulation experiment to optimize the electro-catalytic oxidation experiment’s condition.Through the orthogonal experiment and the single factor influence experiment draw a conclusion that the best working condition by electro-catalytic oxidation treated the simulation cationic dye is pH9.41, current density5.1mA/cm2, electrolyte concentration5g/L, electrolytic time50min.As the results of contrast experiment by different electrolyte that it has good electrochemical catalytic effect through dosing the NaCl electrolyte than Na2SO4. According to the (?)verifying test results that the working condition of this electrode can apply to the other cationic dye,and also can get a higher decoloring rate.The crystal violet molecules has three absorption peaks, respectively for248nm,300nm,582nm.In visible area582nm in absorption band for chromophores absorption belt, ultraviolet area248nm,300nm place with the absorption of fine structure for benzene absorption band. Through the spectral scanning and derivation, it is known that the purple dye molecules in crystal metal niobium cover boron-doped diamond film electrode electrochemical catalysis condition,the dye molecules first form three fang and methyl free radicals, and hydroxyl radicals,such as hypochlorite generation compounds with NN4-dimethylaniline and aniline acid; NN4-dimethylaniline as electrolysis process and hydroxyl radicals forming N-p-trifluoromethylaniline or and protons formed with NN4-dimethylaniline,NN4-dimethylaniline with catalytic process generation compounds N-p-trifluoromethylaniline, N-p-trifluoromethylaniline with further to take off the methyl, take off amino and to take off the carboxyl reaction eventually form the ammonia, carbon dioxide and water; Amino acid catalytic oxidation by electricity to eventually generated by methyl aniline acid, aniline acid methyl, take off the take off again, take off the amino acid eventually form such as ammonia, carbon dioxide and water. Cationic dye hair end system SeJi solely fracture, crystallization purple dyes structure destroyed, to remove chromaticity solution.Using the combination process as flocculating sedimentation and electro-catalytic oxidation to treat the dyeing wastewater of Conghua’s dye factory, the dye wastewater after flocculating sedimentation treated,the effluent water pH for9.4,CODcr for1087mg/L, Chroma for3336times,the removal rate of CODcr and chromaticity respectively for62.05%and30.5%;After the flocculating sedimentation,the effluent water using the electro-catalytic oxidation to treat the rest,the effluent water CODcr for664mg/L, Chroma for40times,pH for alkaline. The whole device for dyeing wastewater CODcr from2860mg/L down to664mg/L, overall degradation rate is76.7%; chroma reduced to40times from4000times, the degradation rate of99.0%,it explained that the combination process for cationic dye wastewater has a good result.According to the cost estimation of test,using the combination process as flocculating sedimentation and electro-catalytic oxidation to treat the dyeing wastewater of Conghua’s dye factory,it’s cost is1.77Yuan/ton,comparison with the combination process by flocculating sedimentation and hydrolysis acidification and contact oxidation and floating,it can surpass0.27Yuan/ton than1.5Yuan/ton.However, compared with it’s project area and project cost and so on,the electro-catalytic oxidation has smaller covers of area and other characteristics,the effluent water is better than the original technology.Overall,this test electric catalytic oxidation process can be used on the actual production application after the further optimization.