Intensification Of Photocatalytic Process For Organic Wastewater Treatment With Microwave Discharge Electrodeless Lamp

Photocatalysis is an attractive technology due to its potential to organic degradation, but still limited to poor light penetration, low mass transfer and catalyst poisoning in wastewater. In order to solve the problems, a "solid" photoreactor and new intensified photocatalytic process were proposed and investigated as the following concerned:1.Refer to the concept of packed-bed reactor, a new "solid" UV source and photoreactor were proposed and constructed as collectives of microwave discharge electrodeless lamp fixed in a glass vessel. Its spectral property and light power were analysed.2.Methyl organic was used as an organic pollutant sample in this work. The operation parameters, including initial concentration of methyl orange, dosage of TiO2 catalyst, and microwave power were investigated to optimize the degradation of methyl orange in the new photoreator. Three kinds of process conditions, microwave (MW), microwave electrodeless lamp (MWL), Microwave assisted photocatalysis (TiO2/MWL) were investigated to explore the active roles of microwave, MWL and the coupling of MWL+TiO2. More than 100mg.L-1 up to 300mg.L-1 methyl orange aqueous solution were conducted in the photocatalytic degradation, which is 2-6 times higher than the literature's report with an initial concentration of methyl orange less than 50mg.L-1. The optimal operation parameters with 75 percentage of methyl orange degradation were microwave power 900W, TiO2 catalyst 1.5g.L-1.3. The effects of inorganic anions on photocatalytic degradation, including chloride, sulphate, carbonate, nitrate, were studied. It was found that sulphate and chloride presented a negative effect on the degradation of methyl orange. However, 0.005mg.L-1 carbonate anions or 0.005mg.L-1,0.02mg.L-1 nitrate anions could promote the degradation of methyl orange. The intermediate products of photocatalytic degradation of methyl orange degradation were analyzed with high performance liquid chromatography (HPLC) and mass spectrometry (MS), and the possible mechanism of photocatalytic degradation of methyl orange in the "solid" photoreactor was proposed.4. The "solid" photoreactor was used to treat two kinds of real wastewater of penicillin wastewater and pesticide wastewater. The experimental results indicate that the heat from microwave and MWL can distill the residual organic solvent in wastewater, and also reduce the COD by photocatalytic oxidation. Therefore, the "solid" photoreactor coupling with distillation and photocatalytic degradation is a good alternative to intensify photocatytic degradation on organic pollutant and expected to develop a new requirement and technology for industrial wastewater in-site.