| Summary: | 碩士 === 國立聯合大學 === 環境與安全衛生工程學系碩士班 === 106 === Liquid Crystal (LC) was innovatively used as a bio-sensor (Liquid-Crystal-Based sensor) in some critical researches due to the specific optical and electrical characteristics of the LC, especially in the files of bio-chemical researches. The LC bio-sensor has been investigated to identify lipase activity, organophosphates, nitrogen dioxide, urea, l-tyrosine, glucose, cholesterol, acetylcholinesterase. In the environmental applications, some modified LC sensors were also investigated to detect the Volatile Organic Compounds (VOCs), ex. glutaraldehyde. The LC sensor was regarded as an innovative, high potential and valuable sensor for many researches, and which was a high interesting and innovative study for many research areas. However, the applications of LC sensor to identify the substances in aquatic environments are very rare and even can no find in the literatures.
In the previous study, the LC sensor was investigated for quantitative identification of four different oxidants in aquatic environments, containing hydrogen peroxide (H2O2), sodium hypochlorite (NaClO), potassium dichromate (K2Cr2O7), and potassium permanganate (KMnO4). The LC sensor was used to quantitatively identified the hydroxyl radical. The measurement of hydroxyl radical is one of the most critical issues in the AOPs relating researches, several techniques including Electron Spin Resonance (ESR), fluorescence, HPLC were investigated to identify the activity of hydroxyl radical in AOPs. However, these methods are expensive, complex, and difficult to be used for on-line application. The main objectives of this study is to develop a LC-based sensor to identify the hydroxyl radical from the AOP processes. Two basic type of nematic LCs (5CB and E7) were used to construct the LC sensor in this study. By analyzing the changes of brightness of LC sensor using image analysis technique, linear relationships were found between the concentrations of oxidants with the durations of the LC disturbance, therefore, the concentrations of hydroxyl radical can be identified. The concentrations of hydroxyl radical from (mg/L to mg/L) can be identiyied. As a result, this proposed LC sensor provides an innovative, rapid, economy application for the quantitative identifications of the oxidants aquatic environments.
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