- 學位論文
利用硫酸鋁及鋁渣去除水中砷之研究
Using Aluminum Sulfate and Aluminum Dross to Remove Arsenic from Water
摘要
環境中砷污染的途徑有兩種，自然礦物風化過程或人為農藥施用等，這些途徑導致砷進入地表水和地下水體，造成水體污染，使之不適於飲用。為了考量經濟成本與技術執行之可行性，尋找價格低廉和有效的砷去除技術為目前主要之目標。 國內鋁回收工業每年會產生大量的鋁渣，鋁渣中的氮化鋁與水接觸會形成惡臭的氨氣及鋁渣中重金屬的溶出現象，導致環境再次污染，採用鋁渣處理含砷溶液可達到環保再利用及零廢棄物之理想。 本研究之目的是先用試藥級硫酸鋁及鋁渣處理含砷水溶液，分析鋁系材料對砷的最佳參數，再利用污泥分析來觀察鋁渣在修正之Wenzel序列萃取法分析的吸附相比較，最後針對試藥級硫酸鋁與鋁渣進行可行性分析及比較。 硫酸鋁混凝實驗中，使用試藥級硫酸鋁處理含砷溶液，在pH值6和室溫的條件，鋁砷比3.3進行震盪30分鐘。鋁渣吸附實驗中，先將鋁渣進行細磨後處理含砷溶液，在室溫下和pH值5–6之間進行震盪2小時。將吸附砷的鋁渣使用總砷分析和序列萃取法進行吸附相的比較。 結果顯示，試藥級硫酸鋁處理含砷溶液，可獲得99%之去除效率與最佳去除能力330.2μg/mg。鋁渣處理含砷溶液，可獲得99 %之去除效率及吸附能力2.17 μg/mg，且鋁渣的吸附屬於自發性反應，並符合Langmuir吸附等溫線與擬二階動力學。在污泥分析，觀察出在鋁渣對砷的吸附相主要是無定形鐵鋁結合相，其次是結晶性鐵鋁結合相與特殊吸附相。 上述結果顯示鋁渣是以鐵與鋁之元素進行砷的去除，並且經由特殊化學吸附，利用表面配位基進行交換反應。將兩種材料進行可行性分析的評估，經由經濟可行性、技術可行性與執行可行性的分析進行比較，得到的結果為試藥級硫酸鋁優於鋁渣。
並列摘要
There are 2 sources make environmental As contamination, natural mineral weathering process and human activity such as pesticides application. Once As flow into surface water or groundwater, it will cause water pollution and undrinkable. Considering the economic and technical feasibility, As removel technology with low cost and high effective is an urgent job. Al recycle industry in Taiwan produces large amounts of Al dross every year. Aluminum nitride (AlN) in Al dross will release ammonia and heavy metals in contacting with water. Using of Al dross to treat As solution may achieve the goal of waste recycle, as well as environmental protection. The aim of this study is using reagent grade Al(SO4)3 and Al dross to treat As contaminated water solution. The optimum parameters for As elimination by using Al-based materials were analyzed. Sludge was used to observe the adsorption phases for As in Al dross by modified Wenzel sequential extraction. Finally, assessments were made between reagent grade aluminum sulfate, As dross by feasibility analysis. In Al(SO4)3 coagulation experiments, reagent grade Al(SO4)3 were used to treat As water solution. Reaction conditions were: Al/As ratio=3.3, pH= 6 and 30 minutes shaking at room temperature. In Al dross adsorption experiments, ground Al dross was used to treat As solution. Reaction conditions were: pH=5-6 and 2 hours shaking at room temperature. Comparison the adsorption phases between the As adsorbed Al dross by using analysis of total As and sequential extraction technology. The results showed that using reagent grade Al(SO4)3 to treat As solution may obtain 99% removal efficiency and the optimum removal capacity of 330.2 μg/mg. Using Al dross to treat As solution may obtain 99% removal efficiency and adsorption capacity of 2.17 μg/mg. The adsorptive of Al dross comes from spontaneous reaction, and followed Langmuir isotherm and pseudo-second kinetics. In the sludge analysis, it observed that the arsenic removal phases in the Al dross is mainly amorphous Fe-Al bonded phase, secondly is a crystalline Fe-Al bonded phase and special adsorbed phase. The above results showed the removal of As by Al dross are based on the elements of Fe and Al, by a special chemical adsorption with surface complexes to processing exchange reaction. Evaluation of three materials by economic, technical and execution feasibility analysis: reagent grade Al(SO4)3 is the best and Al dross is the worst.