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  • 學位論文

利用可磁性回收之綠色覆蓋材料整治多重重金屬污染底泥

Using magnetic recoverable green materials for active capping to remediate multiple heavy metal contaminated sediment

指導教授 : 席行正

摘要


近幾十年的工業活動,人類排放了大量的有害物質到自然水體,其中大多排放的重金屬最終會沉澱在底泥之中,然而如遭受到物理擾動或者是環境條件的改變都會造成底泥中的重金屬再釋出,致使底泥成為環境中重金屬的污染源。在經濟及技術方面的考量上,活性覆蓋法是現行底泥整治方法中是較具有可行性的。然而現行的研究缺乏了長時間穩定性及效果的探討,因此本研究透過合成能以磁性回收之材料,用於抑制重金屬釋出,更期望在適當的時間回收覆蓋材,以避免長時間下穩定性及效果不足之疑慮。 本研究首先合成生物炭、硫化生物炭、磁性生物炭以及硫化磁性生物炭四種材料並對其進行物化分析。分析結果顯示磁性炭以及硫化磁性炭的比表面積遠大於其他兩種材料。XRD的結果顯示兩種磁性生物炭皆有Fe3O4的晶相存在,而這也是兩種材料帶有磁性之原因,另外在硫化磁性炭中也發現了FeS之晶相。接著對這四種材料進行水相吸附以及底泥競爭吸附實驗,結果顯示在水相吸附實驗中生物炭以及硫化生物炭對於鉻、銅、鋅的吸附效果是遠大於兩種磁性炭的,而四種材料皆對鎳沒有任何的吸附效果。在底泥競爭吸附實驗當中,相對於控制組生物炭以及硫化生物炭能夠降低液相的鎳、銅、鋅濃度,而兩種磁性生物炭反而會促進底泥中的重金屬釋出。在微型系統的實驗中發現四種生物炭皆能降低水中銅、汞、甲基汞的濃度。只有硫化磁性炭能夠降低水中鎳及鋅的濃度。而所有生物炭對於鉻皆沒有抑制能力。在實驗的後期硫化炭以及磁性炭有一波汞的釋出,磁性炭以及硫化磁性炭也有著一波甲基汞的釋出。實驗的最後對於兩種帶有磁性的生物炭利用磁鐵進行回收,結果顯示在經過三個月的覆蓋後兩種材料仍能有效的被磁鐵吸引回收。

並列摘要


Humans have discharged heavy metals to environments for decades. A large portion of heavy metal settles to the sediment, and remobilizes through the physical disturbance and the change of the environmental conditions, posing a risk to environments and human health. Among several remediation methods, thin layer capping is considered to be more feasible due to the advantages of financial and technical aspects. However, the long-term effects are still unknown. To deal with the problem, this study used magnetic recoverable amendments to remediate multiple heavy metal contaminated sediment. The study could be divided into three parts, including materials synthesis and analysis, batch adsorption and sediment competitive adsorption experiments, and microcosm experiments. In the first part, biochar (B), sulfurized biochar (SB), magnetic biochar (MB), sulfurized magnetic biochar (SMB) were synthesized. N2 isothermal adsorption results suggested that the specific surface areas of MB and SMB are much higher than those of B and SB. XRD results showed the magnetite crystalline in both MB and SMB, and FeS crystalline in SMB. In the batch adsorption experiment, B and SM showed a better adsorption capacity than MB and SMB in Ni, Cu, and Zn. No materials had an effect on the adsorption of Cr. With the presence of sediment and seawater, B and SB could slightly reduce the concentration of Cu, Ni, and Zn compared to control. MB and SMB facilitated the release of heavy metal due to the change of pH and the oxidation of FeS. In the microcosm experiment, all the materials were able to reduce the concentration of Hg, MeHg, and Cu. Only SMB could reduce the concentration of Ni and Zn. No amendments could effectively reduce the Cr concentration. In the later period of the microcosm, there were short Hg breakthroughs for SB and MB, and MeHg breakthroughs for MB and SMB. At the end of the microcosm, magnetic materials could be collected through commercial magnets successfully.

參考文獻


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