Study On Methyl Orange Dye Wastewater Treatment By Non-thermal Plasma

This paper analysed the characteristics of dye wastewater, hazard of dye wastewater and the current situation in treatment technology. The traditional processing method of dye wastewater treatment has yet reached a satisfactory result. High-voltage discharge plasma technology is a new advanced oxidation technology in recent years, which has obvious advantages in the treatment of refractory wastewater. The according to the existed problems, the paper has been developed a line tube type dielectric barrier non-thermal plasma reactor for treatment of dye wastewater.The reaction device adopts frequency high voltage supply, with the typical wastewater of azo dye methyl orange solution as the research object. The paper has carried out research on the removal efficiency of methyl orange solution by non-thermal plasma, analyzed the reaction intermediate products, and explored the degradation pathways of methyl orange. This paper layed a foundation for the application of low temperature plasma method for the degradation of dye wastewater. The main research contents and conclusions of this paper are as follows:It was found that dielectric barrier discharge plasma can be effective for the removal of the methyl orange dye, especially the decolorization effect is good. The tests were performed to study the reactor electrical operating conditions and initial solution parameters of methyl orange on the removal effect of the research, including the effects of discharge voltage, frequency, electrode form, aeration rate, solution initial concentration, the initial p H of the solution and additive Fe SO4 degradation of methyl orange. The results showed that the removal rate of methyl orange with voltage, frequency and aeration rate increased. The voltage and frequency is higher, the methyl orange in a short period of time the removal rate increases quickly. But the discharge voltage and the frequency increases is limited, not the higher the better. The optimum parameters for this test: In the initial concentration of methyl orange solution was 50mg/L, initial p H=2.95, aeration 2.5m3/h conditions, discharge voltage for 21 k V as and frequency for 275 Hz, degradation 10 min, methyl orange removal rate can reach more than 90%. The outer electrode in the form of the reactor using parallel lines than electrode mesh electrode, the inner electrode line using a round better than the star of the wire electrode. Methyl orange dye removal increased with the initial concentration of the dye decreases, but the absolute removal amount is subsequently increased; Also, the lower the p H value, the more conducive to improve the removal rate of methyl orange dye; Fe SO4 is added separately to the methyl orange wastewater can not improve the efficiency of the degradation of methyl orange.Degradation products of methyl orange dye wastewater analysis found that: The CODcr value of the dye solution showed a trend of increasing at first and then decreasing in the decolorization treatment time. The formation of SO42- and NO3- ions can be detected in the discharge process, and with the increase of the voltage, the higher the concentration of ions, the p H value of the solution is also decreased. The intermediate products were analyzed by GC-MS and the results showed that: Methyl orange chromophore-N=N- substantially damaged, structurally complex organic molecules into smaller molecules degradation acids, alcohols, ketones, etc., but did not make a thorough oxidative decomposition.