活性碳複合黃鐵礦製備及應用於處理四氯化碳之探討

Synthesis of Activated Carbon/Pyrite Materials for the Treatment of Carbon Tetrachloride

簡維均(Weu-Chun Chien) ； 梁振儒(Chenju Liang)

《土壤及地下水污染整治》 4卷3期 (2017/07) Pp. 185-195

https://doi.org/10.6499/JSGR.2017.0403.005

摘要

本研究嘗試製備活性碳(granular activated carbon, GAC)披覆黃鐵礦(pyrite, FeS_2)之反應性吸附材料，並探討其應用於處理四氯化碳(carbon tetrachloride, CT)污染水體之可行性。實驗利用含浸法(impregnation method)及鍛燒法(calcination method)將黃鐵礦披覆至活性碳，形成活性碳-黃鐵礦複合材料，經由掃描式電子顯微鏡分析發現活性碳表面披覆許多角狀黃鐵礦顆粒，其粒徑範圍約在80 ~ 100 nm；批次實驗利用劑量為1 g/L之GAC-FeS_2，於不同pH條件(pH 5.5 ~ 12)，對100 mg/L CT之水溶液進行吸附及還原脫氯試驗，結果pH 12時，GAC-FeS_2可有 效對CT進行吸附並還原降解，反應28天觀測到脫氯百分率約為29%，並偵測到脫氯副產物氯仿(chloroform, CF)生成，相較於其他pH條件，高pH環境下，FeS_2本身氧化速率較快因而加速電子轉移，提升CT還原速率；此外，經X光粉末繞射儀(X-ray diffraction, XRD)分析結果顯示，FeS_2氧化生成赤鐵礦(Fe_2O_3)等鐵氧化物，並且在高pH環境下，鐵氧化物表面帶負電並吸引更多二價鐵鍵結，形成具有較高反應性之表面鍵結二價鐵，提高CT降解反應速率。

關鍵字

氯化有機溶劑 ； 黃鐵礦 ； 吸附 ； 還原脫氯 ； 透水性反應牆

並列摘要

This study attempted to synthesize a reactive activated carbon by coating pyrite (FeS_2) onto granular activated carbon (GAC) for potential use to treat carbon tetrachloride (CT) contamination. The synthetic composites, i.e., GAC-FeS_2 were successfully prepared by impregnation and calcination methods. Scanning electron microscope (SEM) images showed that the particle size of FeS_2 over the GAC surface was about 80 to 100 nm. In batch experiments, the dosage of 1 g/L GAC-FeS_2 under different pHs (pH 5.5-12) was employed for adsorption/dechlorination of 100 mg/L CT in the aqueous phase. The results showed that GAC-FeS_2 can effectively reduce CT within 28 days under pH 12 and 29% dechlorination and byproduct chloroform (CF) were observed. While comparing results among different pHs, dechlorination of CT was faster at a higher pH due as the FeS_2 was promptly oxidized at alkaline pH, and this resulted in a fast electron transfer rate to accelerate dechlorination of CT. In addition, the results of the X-ray diffraction (XRD) analysis showed that the FeS_2 was mainly oxidized to form hematite (Fe_2O_3). The iron oxide species would attract more Fe^(2+) to form high reactive species, i.e., surface-bound Fe^(2+), and then increase the CT reductive reaction rate.

並列關鍵字

chlorinated solvents ； pyrite ； adsorption ； reductive dechlorination ； permeable reactive barrier