粒狀氫氧化鐵去除水中鉬之研究

Removal of molybdenum from water by granular ferric hydroxide

連思琦(Szu-Chi Lien)

指導教授 ： 康世芳

淡江大學/工學院/水資源及環境工程學系碩士班/碩士(2013年)

https://doi.org/10.6846/TKU.2013.01287

摘要

台灣環保署於2008年增訂飲用水水質標準管制鉬0.07 mg/L，本研究評估粒狀氫氧化鐵(GFH)吸附去除水中鉬(Mo)。以ICP-MS分析級(NH4)2MoO4藥劑配製含Mo水樣，操作參數為GFH添加量、pH、Mo初始濃度、接觸時間、溫度及競爭離子(氯鹽、硝酸鹽、硫酸鹽、磷酸鹽)，研究目的為探討:(1)探討操作參數對GFH吸附Mo之影響、(2)GFH吸附Mo之等溫吸附、及(3) GFH吸附Mo之動力吸附。實驗採批次式等溫吸附與動力吸附實驗。
研究結果顯示GFH吸附劑去除Mo可達80%以上，但粉末活性碳與粉末活性鋁去除Mo低於25%，故本研究選擇GFH為吸附劑。GFH表面等電點pH為7.0，吸附Mo之最適pH範圍為4-7，其鉬吸附量為pH 9-10之約5倍。相同GFH添加量，Mo初始濃度越高則對Mo吸附量越大，最大吸附量為25 mg/g；相同Mo初始濃度下，GFH添加量越高，每單位GFH對Mo之吸附量越低。溫度對GFH吸附Mo之效果依序為45℃＞25℃＞10℃。競爭離子以磷酸鹽對GFH吸附Mo影響效果最為顯著，氯鹽、硝酸鹽、硫酸鹽則無顯著影響。此外，GFH吸附Mo可遵循Freundlich等溫吸附式。吸附強度n值大於1，屬於自發性反應；n值隨Mo初始濃度及溫度增加而增加。動力吸附可遵循Lagergern二階(Pseudo-second-order)動力吸附模式。二階動力常數k2值隨GFH添加量增加呈線性增加，但隨Mo初始濃度增加而減小。

關鍵字

鉬 ； 吸附 ； 粒狀氫氧化鐵 ； 等溫吸附 ； 動力吸附

並列摘要

The Taiwan Environmental Protection Agency enforced molybdenum regulation of 0.07 mg/L in drinking water quality standards in 2008. This study evaluates the adsorption of molybdenum (Mo) by granular ferric hydroxide (GFH). All experiments are conducted by batch isothermal and kinetic adsorption methods. The experimental parameters include type and dosage of GFH, pH, initial Mo concentration, contact time, temperature and competitive anions. Moreover, the Mo-containing water sample is prepared from (NH4)2MoO4 ICP-MS analytical-grade solution. The purpose of this study are to investigate (1) the effect of experimental parameters on the adsorption of Mo by GFH, (2) the isothermal adsorption of Mo by GFH, and (3) kinetic adsorption of Mo by GFH.
The results show that the removal of Mo could reach more than 80% by GFH, in contrast, it was less than 25% by both powdered activated carbon and powdered activated aluminum. Thus, GFH was selected as an adsorbent for adsorption of Mo in this study. The isoelectric point of GFH surface was 7.0. The optimum pH for GFH adsorption of Mo ranged from 4 to 7 and the amount of adsorbed Mo is about 5 times as that at pH 9-10. For the same GFH dosage, the amount of adsorbed Mo increased with increasing initial concentration of Mo and the maximum adsorption capacity reached to 25 mg-Mo/g-GFH. However, it decreased with increasing GFH dosage for the same initial concentration of Mo. The order of adsorption efficiency by temperature was 45oC>25oC >10oC. The effect of PO43- on the adsorption of Mo was observed to be stronger than that of Cl-, NO3-, SO42-. Furthermore, the adsorption data fitted the Freundlich isotherm model well. The n value in Freundlich isotherm model was increased with increasing both initial concentration of Mo and temperature. The kinetic adsorption followed the Lagergern pseudo-second-order kinetics. The adsorption rate constant, k2 value increased linearly with increasing GFH dosage, while it decreased with increasing initial concentration of Mo.

並列關鍵字

molybdenum ； adsorption ； granular ferric hydroxide ； Freundlich isotherm ； adsorption kinetic ； competitive anions

參考文獻

36. 蘇憶安(2012) 化學混凝去除水中鉬、銦之研究，淡江大學水資源及環境工程研究所碩士論文。

37. 黃任偉(2002) 粒狀氫氧化鐵吸附地下水中砷之研究，國立成功大學環境工 程學系碩士論文。

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