碩士 / 國立屏東科技大學 / 環境工程與科學系所 / 106 / Large amount of chlorinated organic solvents used in the industrial process, they may leak into the soil and further contaminate the aquifer owing to improper handling or pipeline damage during the process, which will seriously affect the natural environment and the health of the people. Nano-zero-valent iron (nZVI) has been widely used for in-situ remediation. But nZVI is liable to form a passivation layer on the surface in the dechlorination process, and it is not easy to recover and reuse the nZVI as a powder form. Therefore, the goal of this study is to improve the degradation efficacy of nZVI to chlorinated organic pollutants in groundwater by surface modification. The nZVI particles were immobilized by sodium alginate as the carrier and then coated with oleic acid because its high hydrophobicity can decrease the effect of interference salts in water and prefer to degrade the non-aqueous phase liquid (DNAPL). In batch experiments with the nZVI immobilized in alginate beads coated with oleic acid (nZVI-A-O-beads), the particle characteristics such as size and contents as well as the operation parameters affecting the PCE degradation such as the temperature, pollutant concentration, reducing agent dosage, surface modification, interference salt were studied. The test results of PCE degradation with nZVI showed that ORP tended to be stable at the reaction time of 120 min, indicating that nZVI had slowly lost its reducing capacity. While the ORP and PCE degradation curve continued to decrease for PCE degradation with nZVI-A-O-beads at the reaction of 480 min. It was found that oleic acid and sodium alginate did have the function of protecting nZVI particles. The particle sizes of nZVI and nZVI-A-beads were 1.15 μm and 1.87 mm, respectively. It is shown that sodium alginate can be used as a carrier to effectively increase the particle size of nZVI, and can be coupled with a permeable reactive barrier to achieve convenient recycling and reuse. In the batch tests on surface modification of the material, it was found that nZVI-A-O-beads had a better degradation rate of PCE (76.7 %). For the batch tests on variation of addition dose of nZVI, the degradation rate of using 5 g nZVI was better than that of using 1 g nZVI, and the degradation rate was 85.6 %. For the batch tests on the effect of temperature to the degradation of PCE, it had better degradation effect at 45 °C and the degradation rate was 82.5 %. This study found that TCE degraded by nZVI-A-beads or nZVI-A-O-beads is a pseudo first-order reaction. The activation energy of PCE degraded by nZVI-A-O-beads is around 78.8 J/mole. Results of this study show that nZVI is coated and protected by sodium alginate does and oleic acid can reduce the influence of interfering salt in water. With sodium alginate as a carrier, the particle size of nZVI can be increased to achieve the goal of convenient recycling.
| Identifer | oai:union.ndltd.org:TW/106NPUS5615040 |
| Date | January 2018 |
| Creators | Wu, Ke-Li, 吳克禮 |
| Contributors | Huang,Yi-Chu, 黃益助 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 75 |
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