The Investigation Of The Cooperation Of High Voltage Pulsed Discharge And TiO₂ On Treating Dye Wastewater

High voltage pulsed discharge - Photocatalysis is a kind new Advanced Oxidation Technology in wastewater treatment, which combines High voltage pulsed discharge technology with traditional Photocatalysis technology. We investigated the characters of streamer radiating from a multi-needle to plane reactor, which supplied by a positive pulsed voltage power supply in this paper. Then, we used the streamer to induce TiO2 to product catalysis effect. We called this effect as the cooperation of high-voltage pulsed discharge and photocatalysis. In our investigation, this kind of cooperation could largely improve the decoloure efficiency of Acid Orange II (AO7) comparing with only high-voltage pulsed discharge process. The effects of peak voltage, forming capacitance, repeated rate and bubbling quantity to decoloure efficiency of AO7 were discussed in the paper.The conclusions of the paper are summarized as the following.1. The spectrum of streamer radiating from gas-liquid mixture by high-voltage discharge was extensive. We could discover three obvious peaks in UV region, that is 313nm, 337nm and 357nm, in the obtain graph. They belong to the transition of N2 radicals excitated from A2∑+ state to X2∏ state. These UV are all enough to trigger electrons of TiO2 transit from Valance Band (VB) to Conduction Band (CB), and can be used as light source of photocatalysis.2. The quantity of TiO2 adding to the reactor affected decolour efficiency greatly. Within the range of 0-1.2g/L, the efficiency increased with the adding of TiO2 at first. However, when quantity of TiO2 was 0.6g/L, the efficiency reached max. If keeping improving the quantity of TiO2, the efficiency decreased. In our experimental system, the most suitable quantity was 0.6 g/L.3. In the experiment, the decoloure efficiency of AO7 was 83.4% only by high-voltage pulsed discharge within 45min. The efficiency could be improved 14.9% by the cooperation of high-voltage pulsed discharge and TiO2 potocatalysis within the same time. The quantity of TiO2 adding into the reactor was 0.6g/L.4. The peak voltage, forming capacitance, repeated rate and bubbling quantity also had great effect on decoloure efficiency of AO7. The rising of quantity of these factors companied with the increasing of decolour efficiency.5. The process of degrading AO7 by the cooperation of high-voltage pulsed discharge and TiO2 potocatalysis accorded with one-order reactor, Ct=C0e-kt.6. We found that the Abs of AO7 solution was still decreasing after being treated by no mater the process of high-voltage pulsed discharge-TiO2 potocatalysis or the process of only high-voltage pulsed discharge. One of the possible reasons was that AO7 in the water still reacted with H2O2, which hadn't depleted during the process of discharging, yielded byhigh-voltage discharge. The other reason was the reaction between outcomes. These kinds of reactions kept on after discharging.7. TOC of the AO7 solution didn't change much before and after treating within 45min in our experiment. The reason was that the bond of azo group (-N=N-) in AO7 was destroyed by the attacking of free radicals in the system. The broken up of azo group made solution colourless. That is to say, the process hadn't decomposed AO7 into H2O and CO2. There were still planty of organic of aroma in water.