Benhammou A, Yaacoubi A, Nibou L, Tanouti B
Ecole Supérieure de Technologie, Route Dar Si Aissa, BP: 89 Safi, Morocco.
J Hazard Mater. 2005 Jan 31;117(2-3):243-9. doi: 10.1016/j.jhazmat.2004.09.023.
The objective of the present study was to investigate the adsorption of the heavy metals mercury(II) and chromium(VI), from aqueous solutions, onto Moroccan stevensite. A mineralogical and physicochemical characterization of natural stevensite was carried out. In order to improve the adsorption capacity of stevensite for Cr(VI), a preparation of stevensite was carried out. It consists in saturating the stevensite by ferrous iron Fe(II) and reducing the total Fe by Na(2)S(2)O(4). Then, the adsorption experiments were studied in batch reactors at 25+/-3 degrees C. The influence of the pH solution on the Cr(VI) and Hg(II) adsorption was studied in the pH range of 1.5-7.0. The optimum pH for the Cr(VI) adsorption is in the pH range of 2.0-5.0 while that of Hg(II) is at the pH values above 4.0. The adsorption kinetics were tested by a pseudo-second-order model. The adsorption rate of Hg(II) is 54.35 mmol kg(-1)min(-1) and that of Cr(VI) is 7.21 mmol kg(-1)min(-1). The adsorption equilibrium time for Hg(II) and Cr(VI) was reached within 2 and 12 h, respectively. The adsorption isotherms were described by the Dubinin-Radushkevich model. The maximal adsorption capacity for Cr(VI) increases from 13.7 (raw stevensite) to 48.86 mmol kg(-1) (modified stevensite) while that of Hg(II) decreases from 205.8 to 166.9 mmol kg(-1). The mechanism of Hg(II) and Cr(VI) adsorption was discussed.
本研究的目的是研究摩洛哥硅镁石对水溶液中重金属汞（II）和铬（VI）的吸附作用。对天然硅镁石进行了矿物学和物理化学表征。为了提高硅镁石对Cr（VI）的吸附能力，对硅镁石进行了制备。方法是用亚铁Fe（II）使硅镁石饱和，并用Na₂S₂O₄还原总铁量。然后，在25±3℃的间歇式反应器中进行吸附实验。研究了pH值在1.5 - 7.0范围内的溶液对Cr（VI）和Hg（II）吸附的影响。Cr（VI）吸附的最佳pH值在2.0 - 5.0范围内，而Hg（II）的最佳pH值在4.0以上。用准二级模型测试了吸附动力学。Hg（II）的吸附速率为54.35 mmol kg⁻¹min⁻¹，Cr（VI）的吸附速率为7.21 mmol kg⁻¹min⁻¹。Hg（II）和Cr（VI）的吸附平衡时间分别在2小时和12小时内达到。用Dubinin-Radushkevich模型描述了吸附等温线。Cr（VI）的最大吸附容量从13.7（原生硅镁石）增加到48.86 mmol kg⁻¹（改性硅镁石），而Hg（II）的最大吸附容量从205.8降低到166.9 mmol kg⁻¹。讨论了Hg（II）和Cr（VI）的吸附机理。
