复配表面活性剂对油水界面行为和性质影响的模拟研究  

Modeling the effects of mixed surfactants on the behaviors and properties of the oil-water interface with molecular dynamics

作　　者：廖艺 牛亚宾 潘艳秋[1] 俞路[1] LIAO Yi;NIU Yabin;PAN Yanqiu;YU Lu(School of Chemical Engineering,Dalian University of Technology,Dalian 116024,Liaoning,China)

机构地区：[1]大连理工大学化工学院,辽宁大连116024

出　　处：《化工学报》2022年第9期4003-4014,共12页CIESC Journal

基　　金：国家自然科学基金项目(20976020)。

摘　　要：含复配表面活性剂的油田废水是一种多组分复杂体系,研究其中的分子作用关系有助于后续废水处理方案的确定。采用分子动力学(MD)模拟方法建立界面模型,通过定义表面活性剂的关键扭转点及相应的分子夹角、定义协同作用能,结合界面处的密度分布函数等性能模拟和界面张力测试结果,多角度分析两类阴阳离子表面活性剂复配对油水界面特性的影响。结果表明,与含单组分表面活性剂的油水体系相比,复配表面活性剂的相反电荷极性头基间静电吸引作用提高了油水界面稳定性;相较于十二烷基磺酸钠/十六烷基三甲基溴化铵(SLS/CTAB)复配体系,十二烷基硫酸钠/十六烷基三甲基溴化铵(SDS/CTAB)中分子间的协同作用可更好地提高体系的稳定性;当复配表面活性剂的配比为8/10~12/6时的油/水界面稳定效果较优、12/6时稳定性最好。研究结果可为石油开采及油水分离方案的确定提供依据。Oilfield wastewater containing compound surfactants is a multi-component complex system,and the study of molecular interaction is helpful to determine the subsequent wastewater treatment plan.An interface model was established by using molecular dynamics(MD)simulation method.A series of calculations of interfacial properties and the experiment of interfacial tension were performed to examine the effects of two types of anionic/cationic surfactant mixtures on oil/water interfacial property with this model.In particular,this paper defines the concepts of the twist points of surfactants,molecular angles and synergistic energy.The results demonstrated that,compared with the single-component surfactant,the electrostatic attraction between the polar head groups with opposite charges present in mixed surfactants could induce these mixtures to improve the oil/water interface stability.In oil-water systems consisting of mixed surfactants,the intermolecular synergy of sodium dodecyl sulfate/cetyltrimethyl ammonium bromide(SDS/CTAB)mixtures can better enhance the stability of the system compared to sodium dodecyl sulfonate/cetyltrimethyl ammonium bromide(SLS/CTAB)mixtures.The compounding ratio range of SDS/CTAB mixtures that could better stabilize the oil-water interface was from 8/10 to 12/6,with 12/6 being the best.The results could provide programmatic guidance for crude oil extraction and oily wastewater treatment.

关 键 词：乳液 表面活性剂 复配体系 分子模拟 界面行为 油水分离 

分 类 号：TQ423.1[化学工程]