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利用纳米TiO_2对膨润土进行复合改性,制备TiO_2/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Hg~(2+)浓度等条件下,TiO_2/膨润土复合材料对Hg~(2+)的吸附特性与性能,同时通过正交试验,探究TiO_2/膨润土复合材料吸附Hg~(2+)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,TiO_2/膨润土复合材料吸附性能得到极大提高.TiO_2/膨润土复合材料对Hg~(2+)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TiO_2/膨润土复合材料对Hg~(2+)的吸附率随着初始Hg~(2+)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Hg~(2+)的最优实验条件:添加量为2.0 g·L~(-1),pH为8.0,初始Hg~(2+)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).
The structure and morphology of bentonite before and after modification were characterized by scanning electron microscopy and X-ray diffraction.The bentonite was treated with bentonite as control to study the effects of different additives , PH, adsorption time and initial concentration of Hg 2+, the adsorption properties and properties of Hg 2+ on TiO 2 / bentonite composites were investigated. ~ (2+) .The results show that the modified bentonite particles become obviously smaller and the pores and interlayer spacing of loose particles increase, the adsorption capacity of TiO_2 / bentonite composites is much larger than that of bentonite The adsorption rate of Hg 2+ by TiO 2 / bentonite composites increases with the addition amount, pH and adsorption time, with the dosage of 1.5 g · L -1 and the pH of 7.0 , The adsorption rate reached more than 98.0% when the adsorption time was 120 min, but the adsorption rate of Hg 2+ by TiO 2 / bentonite composites decreased with the increase of initial Hg 2+ concentration. Kinetic model fitting found that the adsorption process in line with pseudo-second-order kinetic equation, adsorption by chemical adsorption The adsorption isotherm is more consistent with the Langmuir isotherm equation and belongs to the typical monolayer adsorption with the maximum adsorption capacity of 20.66 mg · g-1. The optimum experimental conditions for the adsorption of Hg 2+: 2.0 g · L ~ (-1), pH 8.0, the initial concentration of Hg 2+ was 45 mg · L -1, the adsorption time was 16 h, the adsorption rate was 99.9% and the equilibrium concentration was 0.034 mg · L ~ (-1).