利用層狀複合金屬氫氧化物即時合成與鍛燒之記憶效應去除水中磷酸鹽之研究

層狀複合金屬氫氧化物(LDHs)為二價與三價金屬離子及陰離子所組成，本研究中所使用為常見的Mg2+與Al3+陽離子金屬，NO3-或CO32-做為可能測試之陰離子，利用即時合成的特性，並在調整不同溶液的pH值下，將Mg2+與Al3+以莫耳比3：1的濃度，配合陰離子加入溶液中與磷酸鹽混合，測試在不同pH值及時間下磷酸鹽的濃度變化，估算出吸附速率與吸附量。另外在記憶效應方面，先以水熱合成法製作出層狀複合金屬氫氧化物，再將合成出來的LDHs於三種不同的溫度下進行鍛燒，冷卻後取得產品，並將製得的產品與含磷酸鹽之水溶液混合，在不同的時間下採樣測定磷酸鹽濃度變化，估算其吸附速率及吸附容量。研究結果顯示，利用即時合成去除水中磷酸鹽的去除效果0.024 mol Mg(NO3)•6H2O、0.008 mol Al(NO3)•9H2O、0.0672 mol NaOH、0.0044 mol Na2CO3為最佳加藥量。在鍛燒之記憶效應方面的吸附效果為：C500-LDHs＞C400-LDHs＞C300-LDHs＞LDHs；而在動力吸附方面試驗之結果則符合Pseudo second order kinetics，吸附效果之結果為：C500-LDHs＞C400-LDHs＞C300-LDHs＞LDHs。實驗證明，LDHs確實可有效去除水體中的磷酸鹽。

關鍵字

層狀複合金屬氫氧化物；磷酸鹽；吸附；即時合成；鍛燒之記憶效應

並列摘要

Layered double hydroxides (LDHs) are composed of divalent trivalent metal ions and anions. This research uses common metal cations such as Mg2+ and Al3+, and test anions such as NO3- or CO32-. Using the in-situ synthesis properties and adjusting different solution pH values, the Mg2+ and Al3+ mole ratio is kept 3:1, and the absorption speed and amount are estimated when anions are mixed with nitrate solution and the nitrate concentration variations are tested at different pH values and time. In terms of the memory effect, LDHs are produced using the hydrothermal synthesis method, and the synthesized LDHs are calcined under three different temperatures. When cooled, the product is mixed with the nitrate-aqueous solution. The absorption rate and amount are then estimated from the nitrate concentration sampled in the given interval. The result shows that using in-situ synthesis, the effects of removing nitrate from water are 0.024 mol Mg(NO3)•6H2O, 0.008 mol Al(NO3)•9H2O, 0.0672 mol NaOH、0.0044 mol Na2CO3, which are therefore the optimal dosage. In terms of the calcination memory effect, the absorption effects are C500-LDHs＞C400-LDHs＞C300-LDHs＞LDHs. The result of the dynamic absorption experiment, on the other hand, is consistent with pseudo second order kinetics, and the result of the absorption effect is C500-LDHs＞C400-LDHs＞C300-LDHs＞LDHs. The experiments demonstrate that LDHs can effectively remove nitrate in water bodies.

並列關鍵字

layered double hydroxides ； nitrate ； absorption ； in-situ synthesis ； memory effect

參考文獻

1. 陳侑利，2013年，「利用流體化床均質顆粒化技術以鐵鹽回收水溶液磷酸之研究」，碩士論文，國立成功大學化學工程學系。.

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