| 纳米TiO2吸附HgCl2水溶液中Hg(Ⅱ) |
| 摘要点击 2423 全文点击 1205 投稿时间：2015-06-20 修订日期：2015-08-13 |
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| 中文关键词 汞 纳米TiO2 吸附 最优条件 吸附等温线 |
| 英文关键词 Hg nano-TiO2 adsorption optimal condition adsorption isotherm |
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| 中文摘要 |
| 通过室内模拟实验研究了3种不同粒径TiO2添加量、溶液pH、吸附时间及初始Hg2+浓度等因素对模拟废水中Hg(Ⅱ)吸附效果的影响. 由单因素研究可知最优条件为:5 nm TiO2和100 nm TiO2添加量分别为7.5g ·L-1和2.0g ·L-1,其它条件相同,溶液pH为8.0,初始Hg2+浓度均为15mg ·L-1,吸附5 min,汞的去除率分别为99.5%和99.3%; 25 nm TiO2添加量为10g ·L-1,溶液pH为8.0,初始Hg2+浓度为15mg ·L-1,吸附60 min时,汞的去除率为62.8%. 3种粒径TiO2吸附Hg(Ⅱ)强弱顺序为:100 nm TiO2 > 5 nm TiO2 > 25 nm TiO2. 分两次量吸附结果表明,5 nm TiO2分量吸附效果明显优于单独吸附效果; 100 nm TiO2的分量吸附与单独吸附差异不大. 正交试验结果表明,影响Hg(Ⅱ)去除率的因素排序为:溶液pH > 初始Hg2+浓度 > 吸附时间 > TiO2添加量. 最优实验方案为:溶液pH=8.0, 100 nm TiO2添加量为2.0g ·L-1,初始Hg2+浓度为25 mg ·L-1,吸附10 min. 在此实验条件下,Hg(Ⅱ)去除率为99.9%,吸附后溶液中Hg(Ⅱ)平衡浓度为0.033 mg ·L-1 < 0.05 mg ·L-1,低于目前企业规定的水污染物中汞的排放限值,Hg(Ⅱ)的最大吸附量为26.95 mg ·g-1. 吸附等温线符合Langmuir等温方程,说明100 nm TiO2对Hg(Ⅱ)的吸附是典型的单分子层吸附. |
| 英文摘要 |
| Mercury removal from aqueous solutions of HgCl2 was studied by indoor simulation experiments, and the effects of three different diameter of particles of Nano-TiO2(Nano-Titanium Dioxide) at different dosage, pH, adsorption time and the initial concentration of Hg2+ on the mercury adsorption from simulated wastewater were investigated. The single factor experiments showed that the optimal conditions were: 7.5g ·L-1 of 5 nm TiO2 or 2.0g ·L-1 of 100 nm TiO2, pH 8.0, initial concentration of Hg2+15 mg ·L-1, adsorption time 5 min, and under these conditions the adsorption rates reached 99.5% and 99.3%, relatively. When the content of 25 nm TiO2 was 10g ·L-1, and the other conditions were pH 8.0, initial concentration of Hg2+ 15mg ·L-1, adsorption time 60 min, the adsorption rate was 62.8%. The Hg(Ⅱ) removal effects of the TiO2 particles with different diameters followed the order of 100 nm TiO2 > 5 nm TiO2 > 25 nm TiO2. Component adsorption results showed that the 5 nm TiO2 component adsorption effect was superior to its single adsorption effect, while there was little difference between 100 nm TiO2 component adsorption effect and its single adsorption effect. The results of orthogonal experiments indicated that the influencing factors of the adsorption rate followed the order of pH > the initial concentration of Hg2+ > time > dosage. The optimal experiment scheme was: pH 8.0, a dosage of 100 nm Nano-TiO2 of 2.0 g ·L-1, an initial Hg2+ concentration of 25 mg ·L-1 and adsorption time of 10 min. Under the experimental conditions, the maximum adsorption rate reached 99.9%, at the same time, the equilibrium concentration of Hg(Ⅱ) was 0.033 mg ·L-1 < 0.05 mg ·L-1, below the current enterprise rules of water pollutants in mercury emissions limits. In addition, the maximum adsorptive capacity was 26.95 mg ·g-1. The adsorption isotherm was in line with the Langmuir isotherm equation, indicating that the Hg(Ⅱ) uptake by 100 nm Nano-TiO2 was typical monolayer adsorption. |
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