本實驗探討利用工業廢棄物合成的鈣礬石吸附處理含硼之工業廢水的效果，其中探討反應動力、硼初始濃度、離子強度、以及溫度對吸附反應的影響。鈣礬石主要利用工業副產物(轉爐石與排煙脫硫石膏)，並添加純硫酸鋁，其莫耳比（[鈣]:[鋁]:[硫酸根]）為3:2:3，平衡酸鹼值為12.02，反應溫度25ºC的環境下合成。
此反應於實驗進行30分鐘後達平衡，並可由擬二階動力學模型來描述。在平衡吸附反應（初始濃度為5-50 mg B/L）中，可得知反應較符合 Langmuir等溫吸附模型。在吸附反應中，不同離子強度（I=0-0.05M 硝酸鈉）對硼之吸附不具影響。由熱力學分析可得知去除硼的反應為自發並放熱的反應。由反應焓變化（∆H° =-127.65 kJ/mol）可推斷此反應主要為化學吸附。我們亦藉由晶相分析及表面分析確認反應機制主要為吸附。本研究充分利用工業廢棄物合成去除硼材料，不僅達到資源循環利用的效益，並且在合成與吸附實驗時所使用較少能源與時間，更可以減少對環境的影響。

The treatment of wastewater containing boron by adsorption through synthesized ettringite was investigated in this study. Ettringite was synthesized using industrial by-products (basic oxygen furnace slag and flue gas desulfurization gypsum) and an addition of pure aluminum sulfate at a molar ratio ([Ca]:[Al]:[SO4]) of 3:2:3 under pHe of 12.02 and 25℃. The synthesized ettringite was characterized by field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD) to ensure the quality and composition.
Kinetic study indicated that boron adsorption reached equilibrium after 30 minutes and followed pseudo-second-order kinetic model. Equilibrium adsorption study (C0=5-50 mg B/L) showed that the reaction was affected by pH and experimental results were better fitted with Langmuir isotherm. The removal of boron seemed to be independent of ionic strength through the range of 0-0.05 M of NaNO3. Thermodynamic analysis revealed that the adsorption process by ettringite was spontaneous and exothermic. The value of standard Gibbs free energy change became less negative with an increase of temperature, implying that the reaction was less favorable with increasing temperature. The magnitude of change of standard enthalpy ("∆H°=" 127.65 kJ/mol) suggests a chemisorption mechanism. Evidence from XRD and FESEM indicated an adsorption process without precipitation reaction involved. The results of this study showed it is feasible to synthesize adsorbent from industrial by-products for the removal of boron from wastewater.

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