Biswal Nihar Ranjan, Rangera Naveen, Singh Jayant K
Department of Chemical Engineering, Indian Institute of Technology Kanpur , Kanpur 208016, India.
J Phys Chem B. 2016 Jul 28;120(29):7265-74. doi: 10.1021/acs.jpcb.6b03763. Epub 2016 Jul 19.
This paper presents the effect of negatively charged silica nanoparticles (NPs) on the interfacial tension of the n-hexane-water system at variable concentrations of four different surfactants, viz., an anionic surfactant, sodium dodecyl sulfate (SDS), a cationic surfactant, cetyltrimethylammonium bromide (CTAB), and two nonionic surfactants, Tween 20 and Triton X-100 (TX-100). The presence of negatively charged silica nanoparticles is found to have a different effect depending on the type of surfactant. In the case of ionic surfactants, SDS and CTAB, silica NPs reduce the interfacial tension of the system. On the contrary, for nonionic surfactants, Tween 20 and TX-100, silica NPs increase the interfacial tension. The increasing/decreasing nature of the interfacial tension in the presence of NPs is well supported by the calculated surface excess concentrations. The diffusion kinetic control (DKC) and statistical rate theory (SRT) models are used to understand the behavior of dynamic interfacial tension of the surfactant-NP-oil-water system. The DKC model is found to describe the studied surfactant-NP-oil-water systems more aptly.
本文介绍了带负电荷的二氧化硅纳米颗粒（NPs）在四种不同表面活性剂（即阴离子表面活性剂十二烷基硫酸钠（SDS）、阳离子表面活性剂十六烷基三甲基溴化铵（CTAB）以及两种非离子表面活性剂吐温20和曲拉通X-100（TX-100））的不同浓度下对正己烷-水体系界面张力的影响。研究发现，带负电荷的二氧化硅纳米颗粒的存在对界面张力的影响因表面活性剂类型而异。对于离子型表面活性剂SDS和CTAB，二氧化硅纳米颗粒会降低体系的界面张力。相反，对于非离子表面活性剂吐温20和TX-100，二氧化硅纳米颗粒会增加界面张力。计算得到的表面过剩浓度很好地支持了纳米颗粒存在时界面张力的增加/降低特性。扩散动力学控制（DKC）模型和统计速率理论（SRT）模型被用于理解表面活性剂-纳米颗粒-油-水体系的动态界面张力行为。结果发现，DKC模型能更恰当地描述所研究的表面活性剂-纳米颗粒-油-水体系。
