Experimental Research On Dye Wastewater Treatment With Dielectric Barrier Discharge

Organic wastewater pollution has become a serious environmental problem with the rapid development of industry, and dye wastewater is one of the key sourcs of typical refractory organic pollutants, especially the dye is forward to photodegradation resistance,anti-oxidation and anti-biodegradation,which made conventional processing methods already can not satisfy the requirement of water treatment technology, therefore, the expert pay high attention in dye wastewater treatment at home and abroad. In recent years, advanced oxidation technologies which mainly produce OH radicals being applied gradually in the water treatment.Acorrding to the development trend of the advanced oxidation technology in the dye wastewaterr which characterized with high mineral concentration, high colority, complications of organic components,high pollution concentration and poison.The paper take acid scarlet GR as target pollutants, dielectric barrier discharge(DBD) plasma could be utilized to degrade the simulation acid scarlet GR wastewater.this paper investigated the factors of discharge voltage, electrode distance,power frequency, reaction time,initial solution concentrations and pH.Farther more, to get the degradation mechanism of acid scarlet GR, the intermediate products in the process of treatment were analyzed by means of high efficiency liquid chromatography and mass spectrography (LC-MS),which provide the scientific basis for the practical application.The results and conclusions of research are as follows:(1)a new-style dielectric barrier discharge(DBD) reactor in which the flowing wastewater being treated was used as the ground plate was used on the degradation of dye wastewater,the partial electric fields were strengthened by the liquid cone induced by the electric field force in the reactor, more active particles were pruducted with the stronger discharge in the discharge space,At the same time, the interfacial mass transfer was enhanced highly with liquid level disturbance.The result show that, acid scarlet GR could be degradated efficiently by DBD.The 76.4% of colorization was removed after 20min DBD decomposition with 10kHz power frequency,8kV discharge voltage,6mm electrode distance,30mg/L initial concentration and 2.0 initial pHï¼›Fe2+ ion could effectively promote decolorization rate of dye wastewater, decolorization rate is increased to 92.1% after 20min with 0.48mmol/L of Fe2+ ion by DBD.(2) The degrading process of acid scarlet GR was determined and analyzed.lt was found that the Variation of CODcr with treatment time was rise-down-rise-down; pH of solution quickly declined along treating time increasing. The UV-Vis spectra show that dye molecules had been destroyed and generated colorless organic acid,aldehyde and so on.The varies of the possible intermediates during the degradation process were monitored with LC-MS,the possible mechanism of acid scarlet GR is proposed,the result show that Hydroxyl radical and ozone mainly attack and destroy C-N of acid scarlet GR molecule,thus making dye decolorization.(3) The concentration of the acid scarlet GR dye in solution decreases exponentially with the lengthening reaction time in the experimental conditions of the different discharge voltage,electrode distance,power frequency,initial concentrations and pH.The kinetic process of the DBD plasma degradation of dyes is not only limited by the number of molecular dyes,active particles and contact effects of both molecular dyes and active particles.In the effectively decolorization experimental conditions,the degradation process accords with the first-order reaction kinetics.(4) DBD was utilized to treat actual dyestuff wastewater,the removal rate of chrominance,turbidity and CODcr is 92.5%,83.3%,52.6% after 24min DBD treatment,the value of BOD5/CODcr was increased to 0.67,biodegradation was improved greatly, which provides conditions for the pre-treatment of the nonbiodegradable organic wastewater.(5) Using ozone which was produced under 8kHz power frequency,8kV discharge voltage and 6mm electrode distance reactor parameters of DBD to treat acid scarlet GR dye, it was founded that dye solution nature of 2.0 initial pH has achieved better result;Respectively using dielectric barrier discharge technology and ozone technique alone for treating the same initial concentration of acid scarlet GR, the decolorization rate of dye was only 41% by ozone alone,but the decolorization rate reached 82% by DBD treatment,which further show that using DBD for treating dye wastewater is of great advantage.