Research On Degradation Of Dye Methylene Blue With High Voltage Pulsed Discharge Cooperating With TiO₂ Photocatalysis

Active species like OH radicals, H2O2, O3, etc. could be generated in gas-liquid pulsed system, and strong UV radiation appeared simultaneously. A technology using the synergistic effect of pulsed discharge and photocatalysis is studied in this paper. Discharge streamer was used as the lamp-house to induce the catalysis activity of nanometer TiO2 photocatalyst. The combination of two Advanced Oxidation Technologies'advantages are low energy efficiency and higher degradation rate besides of fast reaction rate,wide application and no second pollution formed.A new-style discharge reactor has been designed. Using this reactor, the experiments on the degradation of methylene blue (MB) wastewater were done. Process parameters and electricity parameters of this system were studied. The best parameters of this system were found after the Orthogonal Test of main performance parameters. The photocatalyst is analyzed and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and ultraviolet visible diffuse reflectance (UV-Vis DRS).Degradation efficiency of the liquid-phase high voltage pulse discharge and photocatalysis and the combination of these two Advanced Oxidation Technologies were analyzed. The conclusions are as follows:1.Process parameters were researched:0.8 g-L-1 was the best quality of TiO2 photocatalyst for degradation. The removal rate increased as the electrodes distance decreased. The MB was degraded quite efficiently by adding air, when the aeration rate is less then 2 L-min-1 The acid initial pH was favor to degradation of MB, but the degradation rate of alkaline water increased by prolonging time.2.Electricity parameters were researched:MB almost could not be degraded when the voltage was low. Higher voltage was beneficial to degradation.But the degradation rate was negatively affected by higher conductivity. Higher frequency could increase the degradation of MB by applying enough power.3.The optimal values of this system were got by the orthogonal test of main performance parameters. Initial concentration is 10 mg-L',Initial pH is 2.54, inpulse voltage is 10 KV, the concentration of TiO2 photocatalyst doped with Co2+ is 0.8 g-L-1,the electrodes distance is 2 cm, the frequency of voltage is 15 KHz, and the aeration rate is 3 L-min-1.4. The photocatalyst was analyzed and characterized by X-ray diffraction (XRD),scanning electron microscopy (SEM) and ultraviolet visible diffuse reflectance (UV-vis DRS). Active ingredients of the photocatalyst were Titania of anatase type and CoO solid solution. The particle, which diameter was about 20 nm, can reach nanometer level. And the photoresponsive property was improved.5.Added TiO2 photocatalyst which doped with Co2+, the degradation rate of MB was increased to 94.64% form 83.14%.