Research On Degradation Of Ibuprofen Aqueous Solution By Cylindrical Wetted-wall Corona Discharge

Residual pharmaceutical pollutants in water environment are persistent and kinds of micro-pollutants. Due to their non-biodegradable nature, their quantities in living creature would be increasing by bioaccumulation and they would cause potential harmeful impact that may lead to carcinogenesis, teratogenesis and mutagenesis on human beings by the food chain. The environmental safety issues caused by pharmaceutical pollutants are getting more and more attention in recent ten years. Taking ibuprofen, one of the non-steroidal anti-inflammatory drugs, as the target pollutant, we provided a novel method for the effective treatment of wastewater containing ibuprofen in this thesis by investigating the degradation of ibuprofen by non-thermal plasma, which was generated by cyclindrical wetted-wall reactor.Firstly, we studied the effects of the parameters of power supply and reactor (including peak voltage Vp, pulse repetition frequency f, electrode radius r and pulse-forming capatitance Cp) and the parameters of the solution (including the initial concentration Co, flow rate Q and temperature T) on the ibuprofen degradation rate. The results showed that the removal of ibuprofen was greater than 90% when Vp=32 kV.,f=100pps, r=1.5 mm, Cp=0.9 nF, Co=20 mg/1,0=64 L/h, T=298 K. Compared with other AOPs that were used to remove IBP, such as photoelectro-Fenton, photo-Fenton, photocatalysis and sonochemistry, the energy consumption in this thesis was several times or even higher.Secondly, we investigated the effects of different conditions on the relative itensity of spectrum and the variation of TOC, BOD5/COD ratio during the plasma treatment process. We also detected the by-products of ibuprofen degradation and proposed the possible degradatoin pathway. The results showed that the concentration of the active substances generated in plasma had a positive correlation with the discharge power. The TOC removal was not significant in ibuprofen degradation, for example, the TOC was only decreased by 34% after 180 min plasma treatment when the initial concentration of IBP was 60 mg/l, indicating that the remaining by-products were organic compounds. What’s more, the increase of the value of BOD5/COD ratio, rising from 0 to 0.577 after 180 min plasma treatment, indicated that the biodegradability was greatly improved and its toxic effects to the organism were decreasing.Finally, the apparent kinetic of ibuprofen degradation in cylindrical wetted-wall discharge reactor was carried out. We also established a mass transfer-reaction model according to the gas-liquid reaction theory. The results showed that the transfer-reaction of IBP in cylindrical wetted-wall reactor was quasi-fast reaction, and the kinetic order of ibuprofen was one order in the apparent kinetic, while two order in the intrinsic kinetic.