| 氯化铁絮凝-直接过滤工艺对地下水中As(Ⅴ)的去除机制研究 |
| 摘要点击 2843 全文点击 1520 投稿时间：2014-07-22 修订日期：2014-09-01 |
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| 中文关键词 砷 地下水 FeCl3 絮凝-直接过滤 电荷分布多位络合模型 扩展X射线吸收精细结构 |
| 英文关键词 arsenic groundwater ferric chloride flocculation-direct filtration charge-distribution multisite complexation model extended X-ray absorption fine structure (EXAFS) |
| DOI 10.13227/j.hjkx.20150220 |
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| 中文摘要 |
| 为探明氯化铁(FeCl3)絮凝-直接过滤工艺对地下水中砷(As)的去除过程及机制,分别进行了批吸附实验、现场絮凝-直接过滤实验、扩展X射线精细结构光谱(EXAFS)及电荷分布多位络合(CD-MUSIC)模拟.采集的地下水样品As主要为五价[As(Ⅴ)],浓度为40 μg·L-1. 现场柱实验直接过滤工艺中Fe投加量为1.5 mg·L-1,出水As(Ⅴ)浓度均低于10 μg·L-1,92 h内可提供64 984 L安全饮用水. 固体废物毒性浸出实验表明泥饼浸出液中As浓度为3.4 μg·L-1,远低于美国环保署限定值(5 mg·L-1).EXAFS和CD-MUSIC模拟表明FeCl3絮凝去除地下水中As(Ⅴ)存在两种机制:在pH 3~9.5范围内,As(Ⅴ)主要以双齿双核吸附在氢氧化铁上; pH>9.5时,As(Ⅴ)主要与Ca2+和Mg2+形成沉淀而去除. |
| 英文摘要 |
| The As removal process and mechanism from groundwater using ferric flocculation-direct filtration system was investigated using batch, field pilot tests, extended X-ray absorption fine structure (EXAFS) spectroscopy, and charge-distribution multisite complexation (CD-MUSIC) model. The results showed that arsenate [As(Ⅴ)] was the dominant As species in the groundwater with a concentration of 40 μg·L-1. The treatment system could supply 64 984 L As-safe drinking water (<10 μg·L-1) using Fe 1.5 mg·L-1. Toxicity characteristic leaching procedure (TCLP) demonstrated that the leachate As was 3.4 μg·L-1, much lower than the EPA regulatory concentration (5 mg·L-1). EXAFS and CD-MUSIC model indicated that As(Ⅴ) was adsorbed onto ferric hydroxide via bidentate binuclear complexes in the pH range of 3 to 9.5, while formation of precipitate with Ca or Mg dominated the As removal at pH>9.5. |
