結合奈米薄膜/流體化結晶床回收工業製程含銅、鎳廢水之研究

Recovery of Copper, Nickel from Industrial manufacturing process by Nanofiltration Combined with Fluidized Bed Crystallization

陳冠男(Kuan-Nan Chen)

指導教授 ： 陳孝行

國立臺北科技大學/工程學院/環境工程與管理研究所/碩士(2010年)

https://doi.org/10.6841/NTUT.2010.00474

摘要

本研究以奈米過濾（Nanofiltration）結合流體化結晶床（Fluidized bed crystallizers）系統程序，處理工業製程含銅（Cu2+）、鎳（Ni2+）重金屬廢水並達到場內水再生循環利用可行性探討。
研究結果顯示，設定進流水 pH 值為 3 時，奈米薄膜對銅離子截留率為 98.8%、鎳離子截留率為 99.1%，可達到純化二價金屬離子之目的。離子截留效率受到進流水總離子強度大小的影響，進流離子濃度越高，流通量越小，且截留效果越差。此外，奈米薄膜對具相同電性的銅（Cu2+）、鎳（Ni2+）離子截留率取決於離子水合能的大小。當系統操作壓力為 80 psi及低 pH 值，且體積迴流率達到95% 時，銅、鎳離子濃度可濃縮至原水濃度的 22 倍及 28 倍。
流體化結晶床系統中於較佳的操作條件下，以粒徑 0.25∼0.45 mm 為結晶擔體，當碳酸鈉加藥比為 CT/Metal = 6.0，7.0、pH 值 = 8，9、水力停留時間為 20 min 及擔體量 0.382 g/L 時，銅、鎳離子有約 50% 結晶比例且去除效率可達到 99%。在連續操作方面，當進流的銅、鎳離子濃度為 1000 mg/L 時，去除反應不會因操作時間長而降低處理能力，處理過程中所考慮的僅因擔體的增大致使水力停留時間縮短。就反應後進行結晶擔體表面的結構觀察發現，分別為藍色及綠色結晶物覆蓋在擔體上，而經由SEM影像圖可觀測在擔體表面上被棉絮狀物體所覆蓋，且隨時間增加，擔體有增大且呈現團狀及塊狀結晶物；在連續操作後之擔體結晶量於銅離子為 505.2 g/kg-sand、鎳離子為 526.8 g/kg-sand，含量約為總結晶物的 1/8。

關鍵字

薄膜 ； 流體化結晶床 ； 重金屬 ； 濃縮 ； 沉澱

並列摘要

The purpose of this study is to propose a process combining nanofiltration (NF) / fluidized-bed crystallizer (FBC) for industrial manufacturing process to recover heavy metals such as copper and nickel.
The result shows that when the nanofiltration system pH was 3, recovery efficiency for nickel was 99.1 % and recovery efficiency for copper was 98.8 %. Consequently, the pH value in the first stage was determined as 3. For higher concentrations (higher ionic strength), flux and retention decrease, and the rejection of Cu2+ and Ni2+ depended on the hydration energy of ions. When operating pressure reached 80 psi and system volume ratio reached 95 %, the concentration of copper and nickel were concentrated 22 times and 28 times of raw wastewater, respectively.
Besides, the results showed that in the fluidized bed crystallization system, the crystallization efficiency of copper and nickel reached about 50% and the removal efficiency about 99% at feeding ratio of CT/Cu with 6/1, pH 8, feeding ratio of CT/Ni with 7/1, pH 9. In the continuous process, 1000 mg/L of nickel was used as inflow in the fluidized bed, and the results showed that the removal efficiency did not decrease as operation time increased. Moreover, the variation of pellet’s surface was observed during the acidification process and some blue and green crystal coated on pellet’s surface certainty was discovered. The photograph of the pellet’s surface by SEM showed that cotton-shape crystals were grown on the surface of pellet and their sizes increased during the operation. After the continuous operation process, the pellet crystallizes in the copper ion was 505.2 g/kg-sand, the nickel ions was 526.8 g/kg-sand and the tota amount of coated critical was approximately 1/8 of the total crystal.

並列關鍵字

Nanofiltration ； Membrane surface charge ； Membrane pore radii ； Hydration energy ； concentration polarization

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