碩士 / 國立中興大學 / 環境工程學系所 / 105 / Due to the natural landscape, mountains and hills occupy more than 40% of the land area in Taiwan. Thus, the drinking water sources mainly depend on water reservoirs(WRs). Further, the climate, solar irradiance, and excessive nutrients input to these WRs caused serious eutrophication and algal bloom. From 2012 to 2016, the proportion of eutrophic water reservoirs increased year by year. In the past five years, on the main island of Taiwan, the ratio of eutrophic WRs to total WRs raised from 20% to 40%. For the past three consecutive years, all WRs on the isolated island are all eutrophic. Algal bloom in eutrophic water bodies produces not only odorous compounds but also lethal toxins. Microcystis aeruginosa is a common species of cyanobacteria which releases toxins, namely microcystin. Therefore, water quality in these algae-infested WRs is threatening the health of citizens.
Traditional methods cannot solve this environmental health problem. Here, we report an effective way to prepare a new nanohybrid material, magnetic nanosilicate platelet (MNSP), and its effects on the removal of microcystin toxins, inhibition on cyanobacterial growth as well as phosphorus in water. MNSP is fabricated by special treatment of a clay mineral, montmorillonite, and then surface supported with magnetite nanoparticles by in situ synthesis. This nanohybrid can effectively inhibit the growth of Microcystis aeruginosa, that can generate on of the most notorious toxins, i.e. microcystins. Algal cells can be settled at the dosage of 500 ppm MNSP and turbidity can be reduced by more than 67%. The removal of microcystin LR (MC-LR) was as high as 99.39% at an initial MC-LR concentration as high as 100 μg L-1. The adsorption of phosphate reached equilibrium within a period as short as 1 minutes, and the removal rate was higher than 97.8%. Moreover, the removals between pH2.0 and 9.0 were higher than 98% but slightly lower than 95% at pH 10.0. Adsorption isotherm is more likely a Langmuir isotherm. The used MNSP can be recycled by powerful magnets and regenerated by high concentration of NaOH. The removal rate with regenerated MNSP can still be greater than 95%. The anions in the solution managed by Taguchi method are used to compete with the adsorption site on MNSP with phosphate. As a result, the most effective anion is fluoride. These evidences suggested that MNSP is a highly promising material for effective eutrophication control in water bodies.
| Identifer | oai:union.ndltd.org:TW/105NCHU5087018 |
| Date | January 2017 |
| Creators | Bo-Li Lu, 盧柏利 |
| Contributors | 張書奇 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 144 |
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