Influence of ionic strength, electrolyte type, and NOM on As(V) adsorption onto TiO2
Influence of ionic strength, electrolyte type, and NOM on As(V) adsorption onto TiO2
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DOI：
10.1080/10934520701795749
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发表时间：
2008-02
期刊：
影响因子：
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通讯作者：
Guojing Liu;Xiangru Zhang;L. McWilliams;J. Talley;C. Neal
中科院分区：
文献类型：
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作者：
Guojing Liu;Xiangru Zhang;L. McWilliams;J. Talley;C. Neal
研究了不同浓度（0.001-0.1 M）的NaCl或NaClO 4溶液中市售TiO 2（Degussa P25）对As（V）的吸附。研究了天然有机物（NOM）对TiO 2吸附去除As（V）的影响。在碱性条件下（pH 7.0-11.0），As（V）在TiO 2上的吸附随离子强度的增加而增加。在酸性条件下（pH 4.0-6.0），在NaClO 4电解液中，As（V）在TiO 2上的吸附对离子强度不敏感，而在NaCl电解液中，随着离子强度的增大，吸附量降低。在pH 6.0时，无论As（V）初始浓度为1-15 μM，2-15 mg/L NOM作为C的存在都显著降低了As（V）在TiO 2上的吸附量。通过对含有和不含有As（V）的TiO 2的zeta电位的测量表明，As（V）的存在可以使TiO 2的零电荷点（pHpzc）向较低的pH值移动。研究结果表明，As（V）在TiO 2表面既可以形成内球络合物，也可以形成外球络合物，NOM是控制As（V）在TiO 2表面吸附的重要因素。
As(V) adsorption onto a commercially available TiO2 (Degussa P25) in NaCl or NaClO4 at various concentrations (0.001–0.1 M) was investigated. The effect of natural organic matter (NOM) on As(V) removal through the adsorption by TiO2 was also examined. In either electrolyte, As(V) adsorption onto TiO2 increased with the increase of ionic strength under alkaline conditions (pH 7.0–11.0). Under acidic conditions (pH 4.0–6.0), the adsorption of As(V) onto TiO2 was insensitive to ionic strength in NaClO4 electrolyte but decreased with increasing ionic strength in NaCl electrolyte. The presence of 2–15 mg/L NOM as C significantly decreased the fraction of As(V) adsorbed onto TiO2 at pH 6.0 regardless of the initial As(V) concentration (1–15 μM). The measurement of zeta potential of TiO2 with and without As(V) suggests that the presence of As(V) can shift the point of zero charge (pHpzc) of TiO2 to a lower pH value. The overall data presented in this study suggest that As(V) can form both inner-sphere and outer-sphere complexes on TiO2 surface, and NOM is an important factor controlling As(V) adsorption onto TiO2.