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年度	106	專案性質	實驗性質
專案類別	研究專案	研究主題	整治
申請機構	國立台灣大學	申請系所	環境工程學研究所
專案主持人	席行正	職等/職稱	教授
專案中文名稱	應用含硫活性碳以活性覆蓋法針對含汞底泥進行溶出抑制研究
中文關鍵字	活性覆蓋法,含硫活性碳,汞,甲基汞,底泥
專案英文名稱	Using sulfur-impregnated activated carbon for leaching inhibition of mercury containing sediment by active capping method
英文關鍵字	Active capping method, Sulfur-impregnated activated carbon, Mercury, Methylmercury, Sediment
執行金額	1,099,268元
執行期間	2017/1/9 至 2017/11/30
計畫中文摘要	汞因為具有高毒性、揮發性、生物累積性，被認為是最具生物毒性的金屬。在水相中及土壤底泥環境中汞多為二價汞之形式存在。底泥環境因為存在厭氣狀態，有利底泥厭氧微生物經由生物甲基化反應產生甲基汞，為最具毒性與生物累積性的汞物種。汞污染之底泥因此具有很高的生態風險潛勢，更被相關部門視為重要的整治項目。現行整治汞污染底泥的方法主要以開挖法、熱處理法、傳統覆蓋法，或監控生物降解為主，但部分方法因為成本過高、或環境衝擊大等因素，或僅適用低污染底泥，在應用上有許多限制。利用活性碳之活性覆蓋法之新興整治工法，因施工成本低、低環境破壞，可吸附新沉降污染物等優點，具有相當大的潛力。 本研究為加速於未來利用活性覆蓋法整治含汞底泥之實場化，從活性碳材開發、水相吸附試驗、底泥競爭吸附試驗，到汞溶出抑制試驗，逐步探討活性碳在底泥相中對汞的吸附與抑制汞釋出效能。本研究之底泥選用桃園灌溉渠道之底泥並進行汞添加，而吸附材料則使用高品質椰子殼活性碳，並成功熱硫化處理製備成含硫量約4.096 wt%之含硫活性碳並豐富含硫官能基如: C-SO3、C2S(=O)2、C2S=O、C-S-S-C、C-S-C及C-SH。從水相吸附動力學實驗中，AC及SAC皆在吸附時間前6個小時即有良好之去除率，且在約16小時達到平衡。其吸附動力學模式由pseudo-first-order kinetic model模擬較為適切。AC及SAC一階動力吸附方程之吸附常數分別為2.994x10-3 min-1及3.224x10-3 min-1。等溫吸附實驗發現SAC比起AC對於二價汞及甲基汞具有較佳之親和性，SAC與AC對於二價汞及甲基汞之KD值分別為9.4256×〖10〗^4(R2=0.9958)、7.661×〖10〗^5(R2=0.8336)，與3.6942×〖10〗^4 (R2=0.9579)、2.2541×〖10〗^5 (R2=0.9825)。在底泥競爭吸附實驗中，AC對比SAC對於汞具有較佳之抑制溶出能力。利用微型系統之汞溶出抑制試驗發現，活性覆蓋層對於甲基汞之溶出抑制效果較總汞顯著。對於高汞濃度之污染底泥(~250 mg/kg)，本研究之各式覆蓋層(SAC+膨潤土、SAC+TY03底泥、AC+膨潤土)均對甲基汞具有良好溶出抑制能力並能控制甲基汞表水中之甲基汞濃度在大部分時間中小於5 ng/L。在本研究中之活性碳材AC與SAC在所有實驗(水相等溫吸附實驗、底泥競爭吸附實驗，汞溶出抑制實驗)中皆具有良好之抑制汞溶出之能力，並具有應用於活性覆蓋法整治含汞底泥之可行性。
計畫英文摘要	With high toxicity, volatility, and bioaccumulation ability, mercury has been considered one of the most toxic heavy metal in the environment. Mercury exists in the form of double valent mercury in aqueous phase and sediment environment. In sediment environment, it is often anoxic and facilitates biomethylation reactions of mercury, resulting in increasing concentration of methylmercury, which is known as the most toxic form of mercury due to its highest bioaccumulation ability and toxicity. Mercury-contaminated sediment environment is therefore regarded as a highly potential source of generating methylmercury, and remediation of which is often needed to be dealt with in a high priority. The conventional remediation methods such as dredging, capping, or monitored natural recovery, have limited use due to their high cost, great environmental impact, or otherwise being time-consuming or uneffective. Therefore, emerging technologies for mercury-contaminated sediment are needed. Active capping is one of the technologies with many advantages such as cost-effectivness, low environmental impacts, persistency, and ability to adsorb new deposited contaminants. Despite active capping has been considered as a high potential remediation method, relative research is limited other than adsorption isotherm batch experiments in aqueous phase. In order to promote the speed of scaling up active capping method to remediate mercury-contaminated sediment, the proposed one-year research has gone through batch experiments, sediment competition adsorption tests, and microcosm tests to evaluate the adsorption/immobilization capability of activated carbon adsorbents on both mercury and methylmercury. The sediment used in this study was collected in Taoyuan and spiked with various concentrations of mercury solution. High-quality coconet shell activated carbon used in this research was successfully sulfurized to prepare effective mercury adsorber with 4.096 wt% of sulfur, with various of sulfur functional groups such as: C-SO3、C2S(=O)2, C2S=O, C-S-S-C, C-S-C, and C-SH. In kinetic adsorption batch experiment, AC and SAC obtained high removal efficiency of mercury in 6 hours and obtain equlibriam in 16 hours. The correlation using first-order pseudo kinetic model best fitted the adsorption curve of AC and SAC, with constant of 2.994x10-3 min-1 and 3.224x10-3 min-1, respectively. In Isotherm batch experiments, SAC had high affinity to mercury and methylmercury, with KD value of 9.4256×〖10〗^4 (R2=0.9958) and 7.661×〖10〗^5 (R2=0.8336), respectively, compare to KD value of AC at 3.6942×〖10〗^4 (R2=0.9579) and 2.2541×〖10〗^5 (R2=0.9825). In sediment competition adsorption tests, AC had greater performance of inhibiting leaching of Hg in porewater phase, as compared with SAC. In microcosm tests, active caps composed with SAC+bentonite, SAC+TY03 sediment, and AC+bentonite had good performance of inhibiting methylmercury from leaching into overlying water form, and can control methymercury concentration lower than 5 ng/L for most of the test period. In this research, batch experiments, sediment competition adsorption tests, and microcosm tests all suggest that AC and SAC have high performance of inhibition of mercury leaching into water phase; therefore activated carbons may be feasible to applicate as active caps to remediate mercury contaminated sediment.