碩士 / 國立成功大學 / 環境工程學系 / 105 / To control the cyanobacteria and their metabolites in source water, in this study titanium dioxide (TiO2) thin film and hydrogen peroxide (H2O2) were combined with UV-A illumination were examined for their effect on cell integrity and metabolites degradation. In first part, TiO2 thin films were first synthesized using three approaches, including spin coating, hydrothermal, and co-sputtering methods. The best TiO2 thin film synthesized, spin coating at 1500 rpm (SC1500), was obtained based on high hydroxyl radical production and low nanoparticle release. The SC1500 was then analyzed surface properties and used in the batch oxidation and batch incubation experiments for cyanobacteria control.
To understand the effect of hydroxyl radical, H2O2, and UV-A light on cell integrity and microcystins (MCs), oxidation experiments were conducted, using Microcystis aeruginosa as the studied cyanobacterium. In the experiments, cell integrity, hydroxyl radical concentration, residual hydrogen peroxide, MCs concentration were measured, and cell number and cell activity are additionally analyzed in incubation experiments.
The results showed that exposure to long-term hydroxyl radical, for the TiO2 thin film/UV-A system and average radical concentration = 110-15 M, the integrity of
Microcystis cells were impacted. However, the MCs released from the ruptured cells were not degraded. For the system with H2O2, TiO2 thin film and UV-A, the cells were ruptured and the released MCs were more efficiently degraded by radical produced, if compared to the system without addition of H2O2. In addition, adjusting the placing time of TiO2 thin film into the H2O2/UV-A system might enhance the degradation of MCs. Nevertheless, the consumption of H2O2 which resulted in low H2O2 concentration and low hydroxyl radical production, might slow down the reaction rate with Microcystis cells and MCs. For incubation test, it showed low concentration of hydroxyl radical (TiO2 thin film/UV-A system, 10-16M) can inactivate the Microcystis in 16 days, maintaining the MCs concentration to below the guideline value in drinking water announced by WHO. In addition, UV-A irradiance may also inhibit the growth of Microcystis.
Two dual-oxidant kinetic models, including Delayed Chick-Watson Model and Delayed Hom model, were developed and successfully simulated the experimental data of cell integrity. The rate constants between Microcystis cells and H2O2 as well as hydroxyl radical in TiO2 thin film/H2O2/UV-A system were successfully determined by the developed model. The kinetic models for cell rupture were further combined with MCs degradation model to predict the change of MCs concentration over time, and reasonable fits were found between the models and data. The developed models and extracted rate constants may be used to predict cell rupture and MCs degradation when applying TiO2 thin film and H2O2 in natural water for the control the cyanobacteria and metabolites.
| Identifer | oai:union.ndltd.org:TW/105NCKU5515020 |
| Date | January 2017 |
| Creators | Meng-SongTsai, 蔡孟松 |
| Contributors | Tsair-Fuh Lin, 林財富 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 140 |
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