School of Environment, Tsinghua University, Beijing 100084, China.
J Environ Sci (China). 2012;24(8):1525-32. doi: 10.1016/s1001-0742(11)60950-9.
The adsorption of cationic-nonionic mixed surfactant onto bentonite and its effect on bentonite structure were investigated. The objective was to improve the understanding of surfactant behavior on clay mineral for its possible use in remediation technologies of soil and groundwater contaminated by toxic organic compounds. The cationic surfactant used was hexadecylpyridinium bromide (HDPB), and the nonionic surfactant was Triton X-100 (TX100). Adsorption of TX100 was enhanced significantly by the addition of HDPB, but this enhancement decreased with an increase in the fraction of the cationic surfactant. Part of HDPB was replaced by TX100 which decreased the adsorption of HDPB. However, the total adsorbed amount of the mixed surfactant was still increased substantially, indicating the synergistic effect between the cationic and nonionic surfactants. The surfactant-modified bentonite was characterized by Brunauer-Emmett-Teller specific surface area measurement, Fourier transform infrared spectroscopy, and thermogravimetric-derivative thermogravimetric/differential thermal analyses. Surfactant intercalation was found to decrease the bentonite specific surface area, pore volume, and surface roughness and irregularities, as calculated by nitrogen adsorption-desorption isotherms. The co-adsorption of the cationic and nonionic surfactants increased the ordering conformation of the adsorbed surfactants on bentonite, but decreased the thermal stability of the organobentonite system.
研究了阳离子-非离子混合表面活性剂在膨润土上的吸附及其对膨润土结构的影响。目的是为了提高对粘土矿物表面活性剂行为的认识，以便将其可能应用于受有毒有机化合物污染的土壤和地下水的修复技术中。所用的阳离子表面活性剂为十六烷基吡啶溴盐（HDPB），非离子表面活性剂为 Triton X-100（TX100）。TX100 的吸附量因 HDPB 的加入而显著增加，但随着阳离子表面活性剂分数的增加，这种增强作用减小。部分 HDPB 被 TX100 取代，从而减少了 HDPB 的吸附。然而，混合表面活性剂的总吸附量仍有显著增加，表明阳离子和非离子表面活性剂之间存在协同效应。用比表面积测定法、傅里叶变换红外光谱法和热重-导数热重/差热分析对表面活性剂改性膨润土进行了表征。通过氮吸附-解吸等温线计算，发现表面活性剂插层降低了膨润土的比表面积、孔体积和表面粗糙度和不规则度。阳离子和非离子表面活性剂的共吸附增加了吸附在膨润土上的表面活性剂的有序构象，但降低了有机膨润土体系的热稳定性。
