碩士 / 國立屏東科技大學 / 環境工程與科學系所 / 105 / In this study, trichlorethylene (TCE) was used as the target contaminant to investigate the effect of nano-zero-valent iron (nZVI) modification on TCE degradation. Due to the disadvantages of short life of nZVI activity and being susceptible to the interferences, the removal efficiency of chlorinated solvents is limited. Therefore, nano-zero-valent iron immobilized in sodium alginate bead was used to enhance the nZVI activity in this study. The beads were coated by the oleic acid to utilize its high hydrophobicity to decrease the interference of hydrophilic salt and to increase the removal efficiency of target contaminants.
The experiments were conducted in four stages. The first stage was designed to characterize the properties of the nZVI powder, nZVI immobilize in sodium alginate beads (nZVI-A beads) and nZVI-A beads coated with oleic acid (nZVI-A-O beads). The second stage was performed for the background test and for comparison of TCE degradation with nZVI, nZVI-A beads and nZVI-A-O beads. The third stage was designed to study the TCE degradation with nZVI-A-O beads under various operating conditions. Finally, the fourth stage was conducted to investigate the interference of nutrient to TCE degradation with nZVI-A-O beads.
The specific surface area of nZVI and nZVI-A beads is 22.9 and 13.4 m2/g, respectively. The specific surface area of nZVI-A beads is lower than that of nZVI powder. It may be due to the aggregation by Van der Waals during the synthesis process. For the batch test of TCE degradation, the degradation efficiency of nZVI-A-O beads to TCE was slightly lower than that of nZVI-A beads during the initial stage of reaction, but nZVI-A-O beads gradually increased the TCE degradation efficiency during the final stage. At the end, the TCE degradation efficiency was almost the same with nZVI-A and nZVI-A-O beads. It showed that TCE is able to penetrate the outer oleic acid layer of nZVI-A-O beads and ready for dechlorination. For the nutrient interference test, nZVI-A beads were vulnerable to NO3- and PO43− interference resulting in reduction of TCE degradation efficiency. However, nZVI-A-O beads were not affected by NO3- and PO43- interference, the TCE degradation was still promising. During the reaction, pH increased, but both ORP (redox potential) and DO (dissolved oxygen) decreased with reaction time.
This study shows that nZVI-A-O beads can not only effectively prevent themselves from the interference of nutrients, but also demonstrate good potential to TCE degradation. Therefore, the proposed technology can be referred as an alternative for future in-situ remediation of organic chlorinated solvents in aquifer.
| Identifer | oai:union.ndltd.org:TW/105NPUS5615012 |
| Date | January 2017 |
| Creators | LIN,YAN-CHAI, 林彥儕 |
| 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 | 78 |
Page generated in 0.0217 seconds