铝改性凹凸棒土吸附剂在含氟废水中的应用

The Adsorbent of Attapulgite Modified with Aluminum Applicated in Fluorine-Containing Wastewater

以凹凸棒土(ATP)为载体,硫酸铝为活性前驱体,通过浸渍法制得铝改性凹凸棒土(Al^3+/ATP),将其应用于含氟废水中。分析了不同负载化合物、硫酸铝浓度、投加量、pH值等因素对Al^3+/ATP吸附氟离子效果的影响,并探讨相关吸附机理。结果表明:当硫酸铝浓度为0.06 mol/L,固液比为1∶10,40℃下超声20 min,可制得吸附剂;在25℃下,当吸附剂投加量为12.5 g/L,pH值为 5.6,吸附240 min,氟离子的吸附量为3.7708mg/g,去除率可达到94.27%。吸附过程符合 Langmuir等温吸附模型,饱和吸附容量为4.056 8 mg/g;吸附过程用准二级动力学方程更准确。凹凸棒土经过改性后晶体结构未发生明显变化,但比表面积及孔隙体积增大、结晶程度降低,团聚现象减轻。

In this paper, attapulgite (ATP) was used as carrier, aluminum sulfate as active precursor, aluminum-modified attapulgite (Al^3+/ATP) adsorbent was prepared by impregnation method and applied to fluorine-containing wastewater. The effects of different supporting compounds, aluminum sulfate concentration,dosage and pH value on the removal rate of fluorine were respectively analyzed and discussed the related mechanism. The results indicated that optimum modified conditions were 0.06 mol/L concentration of aluminum sulfate, 1∶10 solid-liquid ratio and ultraphonic 20 min at 40 ℃. When the addition amount of adsorbent was 12.5 g/L and the adsorption time was 240 min at 25 ℃, the removal rate of fluorion was 94.27%. The adsorption behavior could be depicted by Langmuir equations, and the saturated adsorption capacity was 4.056 8 mg/g. The adsorption behavior follows a pseudo-second-order kinetic model. Although the crystal structure of Al^3+/ATP didn't change significantly, it could be seen that the surface area and pore increased clearly, the degree of crystallization and the agglomeration phenomenon both decreased, and the surface was more looser.