亲水基团对十二烷基阴离子乳化剂在SiO<sub>2</sub>表面吸附影响的分子动力学模拟与试验研究

全秀洁; 孔令云; 王昊敏; 张艺昕; 罗万力; 杨博

doi:10.13801/j.cnki.fhclxb.20210803.001

亲水基团对十二烷基阴离子乳化剂在SiO₂表面吸附影响的分子动力学模拟与试验研究

doi: 10.13801/j.cnki.fhclxb.20210803.001

1.
重庆交通大学　交通土建工程材料国家地方联合工程实验室，重庆 400000
2.
中铁上海工程局集团(苏州)轨道交通科技研究院有限公司，苏州 215131

基金项目: 国家自然科学基金(51608085)

详细信息

通讯作者:
孔令云，博士，博士生导师，研究方向为沥青路面方面的研究与开发　E-mail：43112443@qq.com

中图分类号: U414
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- 被引次数: 0
出版历程
- 收稿日期: 2021-05-17
- 修回日期: 2021-07-08
- 录用日期: 2021-07-16
- 网络出版日期: 2021-08-04
- 刊出日期: 2022-06-01

Molecular dynamics simulation and experimental study on the influence of hydrophilic group on the adsorption of dodecyl anionic emulsifier on SiO₂ surface

1.
National and Local Joint Engineering Laboratory of Transportation Civil Engineering Materials, Chongqing Jiaotong University, Chongqing 400000, China
2.
Rail Transit Technology Research Institute of Shanghai Civil Engineering Group (Su Zhou) CO. LTD. of China Railway Engineering Group, Suzhou 215131, China

摘要

摘要: 乳化沥青破乳过程中，乳化剂分子亲水基团吸附于集料表面，亲油基团牵引沥青微滴向集料表面聚集，从而达到破乳。因此，为了探究乳化剂亲水基团对乳化沥青破乳过程的影响，通过分子动力学模拟和电导率试验探究了疏水基团为十二烷基碳链、亲水基团不同的5种阴离子乳化剂在玄武岩主要化学成分(SiO₂)表面的吸附情况。模拟结果表明，亲水基团中的K⁺比Na⁺更能增强十二烷基阴离子乳化剂与水分子间的范德华相互作用，促进十二烷基阴离子乳化剂在SiO₂表面的聚集和吸附；在亲水基团中引入苯基官能团可提高十二烷基阴离子乳化剂与水分子间的范德华相互作用、十二烷基阴离子乳化剂在SiO₂表面的吸附能力，苯基官能团的引入率越高，十二烷基阴离子乳化剂与水分子间的范德华相互作用及十二烷基阴离子乳化剂在SiO₂表面的吸附能力越强；由于库仑力的作用，5种十二烷基阴离子乳化剂的疏水基团尾端C原子、亲水基团极性头S原子在SiO₂表面的扩散行为比十二烷基阴离子乳化剂自身在SiO₂表面的扩散行为弱。试验结果表明5种十二烷基阴离子乳化剂在SiO₂表面的吸附量随着乳化剂浓度和固/液比的增大而增加；5种阴离子乳化剂在SiO₂表面的吸附量大小排序与分子动力学模拟的结果一致，验证了结论的可靠性。
- 十二烷基阴离子乳化剂 /
- 亲水基团 /
- SiO₂ /
- 吸附 /
- 分子动力学模拟
Abstract: In the process of emulsified asphalt demulsification, the hydrophilic group of the emulsifier molecule is adsorbed on the surface of the aggregate, and the lipophilic group pulls the asphalt droplets to aggregate on the surface of the aggregate to achieve complete demulsification. Therefore, in order to explore the influence of hydrophilic groups of emulsifier on demulsification process of emulsified asphalt, the adsorption of five kinds of anionic emulsifiers with different hydrophobic groups of dodecyl carbon chain and hydrophilic groups on the surface of the main chemical component (SiO₂) of basalt was explored by molecular dynamics and electrical conductivity experiments. The simulation results show that the K⁺ in the hydrophilic group can enhance the van der Waals interaction between the dodecyl anionic emulsifier and water molecules more than Na⁺, and promote the aggregation and adsorption of the dodecyl anionic emulsifier on the SiO₂ surface. The introduction of phenyl functional group into the hydrophilic group can improve the van der Waals interaction between dodecyl anion emulsifier and water molecules and the adsorption capacity of dodecyl anion emulsifier on the surface of SiO₂. The higher the introduction rate of phenyl functional groups, the stronger the van der Waals interaction between the dodecyl anionic emulsifier and water molecules and the stronger the adsorption capacity of the dodecyl anionic emulsifier on the SiO₂ surface. Because of the action of Coulomb force, the diffusion behavior of C atom at the tail end of hydrophobic group and S atom at the polar head of hydrophilic group on the surface of SiO₂ is weaker than that of the five dodecyl anionic emulsifiers. The experimental results show that the adsorption capacity of five kinds of dodecyl anionic emulsifiers on SiO₂ surface increases with the increase of emulsifier concentration and solid/liquid ratio. The order of the adsorption amount of the five anionic emulsifiers on the SiO₂ surface is consistent with the results in molecular dynamics, which verifies the reliability of the conclusion.
- dodecyl anionic emulsifier /
- hydrophilic group /
- SiO₂ /
- adsorption /
- molecular dynamics simulation

HTML全文

图 1 SiO₂分子模型和超晶胞模型

Figure 1. SiO₂ molecular model and supercell model

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图 2 十二烷基阴离子乳化剂分子式及分子模型

Figure 2. Model of dodecyl anionic emulsifier molecule and water molecule

PDS—Potassium dodecyl sulfate; SDS—Sodium dodecyl sulfate; SDSN—Sodium laurylsulfonate; SDBS—Sodium dodecyl benzene sulfonate; SLDED—Sodium lauryl diphenyl ether disulfonate

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图 3 十二烷基阴离子乳化剂层结构模型

Figure 3. Layer structural model of dodecyl anionic emulsifier

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图 4 1000 ps过程中PDS的能量与温度变化情况

Figure 4. Energy and temperature changes of PDS during 1000 ps

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图 5 S-O_w径向分布函数

Figure 5. Radial distribution function of S-O_w

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图 6 0~1000 ps间十二烷基阴离子乳化剂在Z轴的相对浓度分布

Figure 6. Relative concentration distribution of anionic emulsifiers on the Z axis between 0 ps and 1000 ps

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图 7 800 ps下十二烷基阴离子乳化剂在SiO₂表面及溶液中的分布状况

Figure 7. Distribution of dodecyl anionic emulsifier on SiO₂ surface and solution at 800 ps

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图 8 十二烷基阴离子乳化剂溶液与SiO₂超晶胞间界面能

Figure 8. Interfacial energy between emulsifier solution and SiO₂ supercell

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图 9 十二烷基阴离子乳化剂在SiO₂表面的扩散系数

Figure 9. Diffusion coefficients of emulsifier on SiO₂ surface

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图 10 5种十二烷基阴离子乳化剂形貌

Figure 10. Morphologies of 5 dodecyl anionic emulsifiers

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图 11 不同固/液比下5种十二烷基阴离子乳化剂在SiO₂表面的吸附量

Figure 11. Adsorption capacity of five anionic emulsifiers on the SiO₂ surface under different solid/liquid ratios

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表 1 十二烷基阴离子乳化剂溶液盒子尺寸

Table 1. Dodecyl anionic emulsifier solution box size

Emulsifier solution	N_water	N_emulsifier	Cubic size/nm
SDBS solution	1543	20	2.99×2.99×6.44
SDSN solution	1210	20	2.99×2.99×5.05
SDS solution	1280	20	2.99×2.99×5.34
PDS solution	1351	20	2.99×2.99×5.64
SLDED solution	2403	20	2.99×2.99×10.03
Notes: N_water—Number of water molecules; N_emulsifier—Number of dodecyl anionic emulsifier molecule.

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表 2 乳化剂亲水基团水合层内水分子个数

Table 2. Number of water molecules in the hydration layer of hydrophilic group of emulsifier

Types of anionic emulsifiers	PDS	SDS	SDSN	SDBS	SLDED
S-O_w	47.655	25.896	26.009	25.716	46.720

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表 3 电导率试验化学试剂相关参数

Table 3. Relevant parameters of chemical reagents for conductivity test

Name	Abbreviation	Content/%	Morphology	Origin
Sodium dodecyl benzene sulfonate	SDBS	99	Powder solid	Hefei BASF Biotechnology CO., LTD.
Sodium dodecyl sulfate	SDS	90	Powder solid	Shandong Yousuo Chemical Technology CO., LTD.
Potassium dodecyl sulfate	PDS	94	Granular solid	Shandong Yousuo Chemical Technology CO., LTD.
Sodium laurylsulfonate	SDSN	99	Powder solid	Hefei BASF Biotechnology CO., LTD.
Sodium Lauryl Diphenyl Ether Disulfonate	SLDED	45	Liquid	Shandong Yousuo Chemical Technology CO., LTD.
Silicon dioxide	SiO₂	99	Powder solid	Tianjin Zhiyuan Chemical Reagent CO., LTD.

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