離子交換法處理含氫氟酸與氟矽酸的半導體廢水之研究

Ion Exchange Treatment of Semiconductor Hydrofluoric and Hydrofluosilicic Acid Wastewater

姚洋羽(Yang Y. Yao)

指導教授 ： 林勝雄

元智大學/工程學院/化學工程與材料科學學系/碩士(2003年)

摘要

半導體工業中常使用氫氟酸來蝕刻晶圓表面與清洗用具，在蝕刻與清洗的過程中，部分氫氟酸會與晶圓中的矽產生反應而生成氟矽酸，蝕刻後再用大量的水清洗晶元，而造成大量的氫氟酸廢水，因廢水中氫氟酸濃度低處理不易。本研究針對以離子交換樹脂處理溶液中的氫氟酸與氟矽酸，最終達到提高濃度再利用的目的。本研究探討雙成份的吸附行為，研究的重點在雙成份批次吸附之平衡行為、雙成份管柱吸附之情形、理論模式的探討以及脫附變因討論。
本實驗探討著重在雙成份的吸附情形，並利用離子交換四步驟將氫氟酸提濃再利用。首先第一步利用強鹼OH型樹脂中的OH基和氫氟酸與氟矽酸的溶液進行吸附置換的動作，目的在於去除水中氟離子；第二步為將吸附飽和的OH型樹脂，利用高濃度的脫附劑NaOH來將樹脂再生，不但樹脂得以回收再利用，並且可收集到高濃度的氟離子；第三步為利用H型樹脂的H基和氟化鈉與氟矽酸鈉中的鈉離子進行吸附置換的動作，最終將可得到我們所需要的氫氟酸；第四步為將吸附飽和的H型樹脂，利用高濃度的脫附劑HCl進行再生。
批次實驗中，主要著重在雙成份的吸附情形，並以Langmuir、extended -Langmuir和Freundlich等溫吸附式來和實驗數據來進行模擬比較。
管柱吸附實驗中的主要變因則是探討不同進料流速、進料濃度對吸附系統的影響，並以Simplified Logistic-1、Richards和Hill模式模擬實際的吸附情形，另外也對現場廢水的吸附情形加以探討。
最後，本實驗探討不同的再生方法，在批次的實驗中，強鹼OH型樹脂經過兩次吸附與再生，再生效率可達97.8% ；強酸H型樹脂經過兩次吸附與再生，再生效率可達98.1%。管柱實驗中以脫附劑進料流速、進料濃度與反應的溫度為討論的變因，目的在於成本的節省與尋找氟離子濃度的最佳條件。
由實驗結果可知，要將氫氟酸廢水濃度提高，利用離子交換法是可行的，只要條件適當，可將氫氟酸濃度提高至十倍以上。

關鍵字

氫氟酸 ； 氟矽酸 ； 廢水 ； 離子交換法

並列摘要

Hydrofluoric acid has been commonly used in tile semiconductor industries for wafer etching and tool cleaning. Those processes lead to generation of large quantity of waste acid solution which comprises primarily the hydrofluoric (HF) and hydrofluorosilicic (FSA) acids. The objective of this study is to utilize ion exchange resins to recover both
acids from waste solution. The present investigation focuses on the batch equilibrium and column ion exchange experimental tests and the related theoretical modeling using the appropriate ion exchange models.
Two types of ion exchange resins were used in the present study. The strong basic OH-type resin was to capture HF and FSA from the waste acid solution in the first step while the strong acid H-type resin served to convert NaF and Na2SiF6, obtained from the OH-type resin to HF and FSA in the second step. Batch experimental tests were carried out to determine the equilibrium ion exchange capacities of both resins under competitive ion exchange conditions of the two-component (HF/FSA) system. Various isotherms, including Langmuir, extended Langmuir and Freundlich types, were adopted and tested to model the equilibrium ion exchange of the two-component system. The verified isotherms permit easy estimation of the equilibrium ion exchange capacities of both resins.
Column tests were performed primarily to determine the ion exchange characteristics under continuous flow conditions. The two operating variables were the feed flow rate and the inlet HF arid FSA concentrations in the feed. Breakthrough data of the column tests were collected. Different breakthrough models, like the simplified logistic, Richards and Hill models, were adopted to simulate the breakthrough characteristics. Using the observed data, statistic best model fit am obtained by proper identification of the model parameters.
In addition to batch equilibrium and column ion exchange tests, regeneration of the exhausted resins was also conducted. Experimental tests were to determine the type of regenerant to be used and the regeneration conditions. The test variables consisted of feed flow rate and inlet concentration of regenerant and operating temperature. The observed
batch and column data allowed determination of optimum operating conditions of the regeneration process.

並列關鍵字

Hydrofluoric ； Hydrofluosilicic ； Wastewater ； Ion Exchange

參考文獻

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