凹凸棒石和海泡石对镉离子的吸附效果

    Effects of Attapulgite and Sepiolite Adsorbing Cadmium in Aqueous Solution

    • 摘要: 采用静态批试验方法研究了凹凸棒石和海泡石对溶液中Cd2+的吸附特性,并通过考察一定离子强度下,不同初始浓度、固液比、吸附时间和pH值对吸附镉的影响。结果显示:在0.01 mol·L-1NaNO3离子强度下,高品位海泡石、凹凸棒石和低品位凹凸棒石对溶液中Cd2+的吸附量与初始浓度呈正比,与固液比呈反比;根据Langmuir等温吸附方程拟合结果,在给定离子强度25℃条件下黏土矿物Cd2+的理论饱和吸附量从大到小依次为高品位凹凸棒石(33.67 mg·g-1)、高品位海泡石(25.55 mg·g-1)、低品位凹凸棒石(11.52 mg·g-1)和低品位海泡石(5.24 mg·g-1);Cd2+在海泡石、凹凸棒石上的吸附受pH值的影响较大,在pH值为2~4时吸附效果最好;凹凸棒石对Cd2+的吸附较为稳定,在3 h时基本达到吸附平衡;在离子强度为0.01 mol·L-1 NaNO3、Cd2+初始浓度为625 mg·L-1、黏土矿物添加量为15 g·L-1和pH值为2~4时,去除效果从大到小依次为高品位海泡石、高品位凹凸棒石、低品位凹凸棒石和低品位海泡石。

       

      Abstract: Effects of attapulgite and sepiolite adsorbing Cd2+ in aqueous solutions relative to initial concentration, solid-liquid ratio, exposure duration, and pH were investigated through a static batch experiment under a set NaNO3 ionic strength (0.01 mol·L-1). Results show that, under the set NaNO3 ionic strength, Cd2+ adsorption of sepiolite and attapulgite of high grade and attapulgite of low grade is positively related to initial concentration of Cd2+ in the solution, but negatively to solid-liquid ratio of the solution. Fitting with the Langmuir isothermal adsorption equation reveals an order of high grade attapulgite (33.67 mg·g-1) >high grade sepiolite (25.55 mg·g-1) >low grade attapulgite(11.52 mg·g-1) >low grade sepiolite (5.24 mg·g-1) in terms of theoretical saturated Cd2+adsorption; Cd2+ adsorption on sepiolite and attapulgite is strongly influenced by pH of the solution, and peaks when pH is 2-4; Cd2+ adsorption on attapulgite is relatively stable and reaches equilibrium basically in 3 h; in solutions 0.01 mol·L-1 NaNO3 in ionic strength, 625 mg·L-1 in initial Cd2+ concentration, 15 g·L-1 in clay mineral addition amount and 2-4 in pH, the minerals display an order of high grade sepiolite >high grade attapulgite >low grade attapulgite >low grade sepiolite in terms of Cd removal efficiency.

       

    /

    返回文章
    返回