Degradation of Microcystis aeruginosa cells and microcystins in the system of titanium dioxide and hydrogen peroxide under UV-LED condition

• Main Authors: Wei-TingHuang, 黃暐庭
• Other Authors: Tsair-Fuh Lin
• Format: Others
• Language: zh-TW
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/13996583002796742016

碩士 === 國立成功大學 === 環境工程學系 === 104 === Effect of TiO2 and H2O2 on Microcystis aeruginosa and the degradation of microcystins (MCs) under UV-LED light illumination was investigated. The study is divided into two parts. In the first part, the powder TiO2 was used as photocatalyst, and it is one of the sources to produce hydroxyl radical (･OH). As the powder TiO2 may block the light penetration into deeper water, higher dose of TiO2 applied did not lead to higher production of ･OH. Four main factors namely TiO2, H2O2, ･OH, and UV-LED light were examined individually for their effects on cell integrity and cell activity of Microcystis. It was observed that the H2O2 may significantly reduce the cell integrity and cell activity of Microcystis. Low concentration of ･OH produced in the experiments (10^(-14~-15)M) is not able to rupture the cells, but it can increase the rupture rates caused by H2O2. Results of MCs concentration in the system indicate that ･OH is crucial for the degradation of MCs released from ruptured cells, and higher concentrations of ･OH resulted in higher degradation rates of MCs. A sequential model, including one sub-model to simulate the kinetics for cell integrity of Microcysis, and another one to describe the release and degradation of MCs, was developed in this study. Among the commonly used models for describing cell rupture, the Delayed Chick-Watson model gave best simulation for the change of cell integrity over time, and after combining with the degradation model for MCs in water, it is able to predict the observed concentration of MCs in the water. In the second part, TiO2 thin film produced by RF sputtering system was used as photocatalyst. Because of the low surface area, the concentration of ･OH is very low in this system. Therefore, increasing the thinkness and the dosage of TiO2 film is suggested to be included in future study for better efficiency for ･OH production.