| Summary: | 碩士 === 國立聯合大學 === 環境與安全衛生工程學系碩士班 === 107 === Application Advanced Oxidation Processed (AOPs) deal with organic pollutants has become the main trend now in recent years. Among the free radicals produced in AOPs, such as: hydroxyl radicals, superoxide radicals, sulfate radicals, etc. The concentration of radicals is an important indicator in wastewater treatment. However, the detection method of radicals at this stage is indirect detection, and it requires the use of Precision Instruments and time-consuming detection, such as: Electron Paramagnetic Resonance (EPR).
In this study, a UV (365 nm) modified liquid crystal sensor was used to detect the concentration of sulfate radicals in water. And to explore the homeotropic orientation ability of the UV(365 nm)-treated liquid crystals at different times. The results show that the liquid crystal (5CB : E7 = 1 : 1 ) with UV light (365nm) for 50hr, it can detect hydrogen peroxide concentration of 50-200 mg/L in one minute. And using the liquid crystal sensor to detect different concentrations of sodium persulfate aqueous solution and using the sulfate radical generated by the UV photocatalytic reaction (SO4-·), the sulfate radical concentration in the water can be detected. Different sulfate radical concentrations and liquid crystal reaction termination times are also different, The liquid crystal reaction termination time and sodium persulfate concentration can reach a linear relationship of R2=0.9274. In order to further investigate the feasibility of liquid crystal sensor for the determination of sulfate radicals, the chroma removal efficiency of orange G dye wastewater was removed by photocatalytic reaction with sodium persulfate solution, and compared with the liquid crystal reaction termination time, it can be found that it has positive Correlation, and R2 can reach 0.9059 and 0.8771, so it is possible to confirm the feasibility of the liquid crystal sensor for detecting sulfate radicals.
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