A Study On Treatment Of Wastewater Containing Azo Dye Based On Solar Step Process

The dye industry as one of the important industries,it is a high polluting industry,where a lot of high chroma,high COD,high toxicity and refractory organic pollutants are released into the water.These toxic substances cause great threat to ecological environment and human life,and also cause serious damage to the life on earth.The azo dye is the main source of the dye wastewater.At present many traditional processing methods of methyl orange dye wastewater have some limitations,and waste water after treatment can not meet the emission standard.So a new oxidation technique has become a hot spot in the field of scientific research,and the solar energy that is a new kind of clean and green energy has more and more attention.Solar energy STEP technology is based on solar energy,and with the synergy of light-electric effect,light-heating effect and solar electrochemical effect,solar energy conversion is in high efficiency.The solar energy is applied in the field of environmental protection,and solar energy utilization efficiency is also improved.STEP is an efficient and environmentally friendly wastewater treatment technology and able to thoroughly degrade organics.This article methyl orange was as the azo dye model.We applied solar energy STEP process to methyl orange wastewater firstly.In experiment the solar light-heat and light-electric unit were builded,and the azo dye wastewater of methyl orange was degraded combined with light-heat and light-electricity effect.With platinum as working electrode,the experimental factors including voltage,current,temperature,electrolyte and pH were investigated.Ultraviolet spectrum and the removal rate of COD are the methods to evaluate the degradation of methyl orange.According to the experiment datas of methyl orange degradation,kinetics analysis was researched,at the same time through the ultraviolet spectrum and HPLC detection and analysis,the mechanism of the oxidation degradation of methyl orange was speculated.Studies have shown when the temperature 40?,the degradation time 60 min,and the voltage from 1V to 4V,methyl orange wastewater COD removal rate increases gradually to 30%;When constant voltage 3V,the degradation time 60 min,and the temperature from 20? to 80?,wastewater COD removal rate reaches 43%.When the temperature 40?,the electrolytic current 10 mA,and the time 60 min,with acidand alkaline of the solution pH from 3 to 11,the removal rate of COD gradually reduces.When pH=3 the removal rate of COD is 31.9%;When the temperature 80?,pH=3,constant current of 10 mA,the degradation time 150 min,COD removal rate reaches 65.2%.According to the analysis of experimental data,the degradation of methyl orange conforms to the first order kinetics.Further by ultraviolet spectrum and HPLC analysis,the intermediate products of the degradation of methyl orange azo dye in the process of solar STEP are aniline,hydroquinone,benzoquinone and maleic acid.