| TiO2/膨润土复合材料对Hg2+的吸附性能研究 |
| 摘要点击 2925 全文点击 1165 投稿时间：2016-07-25 修订日期：2016-09-04 |
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| 中文关键词 汞 改性 TiO2/膨润土复合材料 吸附特征 最优条件 |
| 英文关键词 mercury modification TiO2/bentonite composite adsorption characteristic optimal condition |
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| 中文摘要 |
| 利用纳米TiO2对膨润土进行复合改性，制备TiO2/膨润土复合材料.采用电镜扫描、X-射线衍射表征改性前后膨润土的结构和形貌.通过室内模拟实验，以膨润土为对照，研究不同添加量、pH、吸附时间及初始Hg2+浓度等条件下，TiO2/膨润土复合材料对Hg2+的吸附特性与性能，同时通过正交试验，探究TiO2/膨润土复合材料吸附Hg2+的最优条件.结果表明，改性后的膨润土颗粒明显变小，且颗粒疏松多空孔，层间距增大.相比于膨润土，TiO2/膨润土复合材料吸附性能得到极大提高.TiO2/膨润土复合材料对Hg2+的吸附率均随着添加量、pH、吸附时间的增大而增大，添加量为1.5 g·L-1、pH为7.0、吸附时间为120 min时，吸附率达98.0%以上.但TiO2/膨润土复合材料对Hg2+的吸附率随着初始Hg2+浓度的增大而减小.通过4种动力学模型拟合发现，吸附过程符合假二级动力学方程，吸附以化学吸附为主.吸附等温线更符合Langmuir等温方程，属于典型的单分子层吸附，最大吸附量为20.66 mg·g-1.吸附Hg2+的最优实验条件：添加量为2.0 g·L-1，pH为8.0，初始Hg2+浓度为45 mg·L-1，吸附时间为16 h，此时吸附率99.9%，平衡浓度为0.034 mg·L-1. |
| 英文摘要 |
| The TiO2/bentonite composite was synthesized by modifying calcium-based bentonite with Nano-TiO2. The products before and after modification were characterized via the approach of X-ray power diffraction(XRD) and scanning electron microscope(SEM).The effect of TiO2/bentonite composite on mercury removal from aqueous solutions of HgCl2was studied at different dosage, pH, adsorption time and the initial concentration of Hg2+ was investigated and compared with the bentonite by indoor simulation experiment, as well as the orthogonal experiments to determine the optimal condition of Hg2+ adsorption. The experimental results showed:after modified by TiO2, TiO2/bentonite composite particles were apparently smaller, the basal spacing was increased and with a loose and porous structure. The adsorption rates of TiO2/bentonite composite on Hg2+ were increased compared with bentonite. The Hg2+ adsorption rates were increased with the increasing dosages, pH and adsorption time. The adsorption rates were higher than 98.0% when the dosage was 1.5 g·L-1, pH 7.0, and the adsorption time was 120 min. The adsorption rates became smaller with increasing initial concentration of Hg2+. False secondary dynamic equation could describe the adsorption of TiO2/bentonite composite on Hg2+, and the chemical adsorption was dominant. The adsorption isotherm of Hg2+ conformed to Langmuir equation, indicating that the adsorption of Hg2+ was typical monolayer adsorption. The optimal experimental condition was:dosage of 2.0 g·L-1, pH 8.0, adsorption time of 16 h and the initial Hg2+concentration of 45 mg·L-1. Under this condition, the adsorption rate was 99.9%, and the equilibrium concentration of Hg2+ was 0.034 mg·L-1 |
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