Effect of CaCl2 on the property of an anionic surfactant monolayer formed at the air/water interface: a molecular dynamics study

1st International Global on Renewable Energy and Development

Zhang, Tiantian^1 ; You, Jing^1 ; Yu, Jiliang^1 ; Fan, Chengcheng^2 ; Ma, Yunfei^3 ; Cui, Yanjie^1 ; Gao, Shanshan^1 ; Li, Yongbin^1 ; Hu, Songqing^4,5 ; Liu, Huiqin^6

Petroleum Production Engineering Research Institute of Huabei Oilfield Company, Renqiu Hebei

062552, China^1

Spang Technology Company, Shanghai, Shanghai

201210, China^2

China Petroleum Engineering and Construction Corporation North China Company, Renqiu Hebei

062550, China^3

College of Science, China University of Petroleum, Qingdao, Shandong

266580, China^4

Key Laboratory of New Energy Physics and Materials Science in Universities of Shandong, Qingdao, Shandong

266580, China^5

Technical Supervision and Inspection Department of Huabei Oilfield Company, Renqiu Hebei

062552, China^6

关键词: Aggregation behaviours;    Air/Water Interfaces;    Degree of hydration;    Electric double layer;    Hydrophilic headgroups;    Molecular dynamics simulations;    Radial distribution functions;    Surfactant monolayers;   

Others  :  https://iopscience.iop.org/article/10.1088/1755-1315/100/1/012081/pdf
DOI  :  10.1088/1755-1315/100/1/012081

来源: IOP

【 摘 要 】

Molecular dynamics simulation had been carried out to investigate the influence of CaCl2on the aggregation behaviour of sodium dodecyl polyoxyethylene sulfonate (A12E2SO3) at the air/water interface. First, structure properties of A12E2SO3monolayer was studied by analyzing the snapshots of the configuration and density profiles of different components in A12E2SO3systems. Results showed that Ca2+could replace some Na+to combine with the hydrophilic headgroups. Besides, the addition of CaCl2could reduce the thickness of water layer at the interface. Second, the interactions between A12E2SO3headgroups and water molecules were studied through calculating radial distribution functions (RDFs) between water molecules and the sulfonate group, as well as the oxyethyl group. Results revealed that Ca2+could penetrate the hydration layer of the sulfonate group, but could not enter the first hydration layer of the oxygen ethyl group close to the sulfonate group. The addition of CaCl2could make the degree of hydration more orderly and the thickness of hydration layer in the headgroups of A12E2SO3molecules increase. Third, the property of interface double layer was studied through analyzing RDFs of the headgroups and counterions. Results showed that the addition of CaCl2could not only reduce the interaction between the headgroups and the counterions, but also compress the thickness of the electric double layer in A12E2SO3system.