物理化学学报 >> 2012, Vol. 28 >> Issue (01): 201-207.doi: 10.3866/PKU.WHXB201228201

催化和表面科学 上一篇    下一篇

云母表面吸附烷基伯胺对其疏水性的影响

刘臻, 刘够生, 于建国   

  1. 华东理工大学化学工程联合国家重点实验室, 上海 200237
  • 收稿日期:2011-07-18 修回日期:2011-10-26 发布日期:2011-12-29
  • 通讯作者: 刘够生 E-mail:gsliu@ecust.edu.cn
  • 基金资助:

    国家自然科学基金(51164009)资助项目

Effect of Primary Alkylamine Adsorption on Muscovite Hydrophobicity

LIU Zhen, LIU Gou-Sheng, YU Jian-Guo   

  1. State Key Laboratory of Chemical Engineering, East China University of Science and Technology, Shanghai 200237, P. R. China
  • Received:2011-07-18 Revised:2011-10-26 Published:2011-12-29
  • Contact: LIU Gou-Sheng E-mail:gsliu@ecust.edu.cn
  • Supported by:

    The project was supported by the National Natural Science Foundation of China (51164009).

摘要: 矿物表面的疏水性受吸附在其表面的表面活性剂的影响, 进而影响矿物的浮选行为. 本文通过表面接触角测量、原子力显微镜(AFM)观测以及密度泛函理论(DFT)和分子动力学(MD)模拟计算, 研究了吸附在云母表面的烷基伯胺的链长对其疏水性的影响. 通过比较氧密度和氢键数量分布, 发现每个水分子在碳氢链尾端和水相接触的界面上相对于在体相中形成氢键的能力有所降低, 而吸附烷基伯胺的云母由亲水性转化为疏水性.研究结果还表明, 在单分子层吸附状态下, 吸附十八胺的云母的疏水性比吸附十二胺的云母的疏水性要强, 且由于十八胺的临界半胶束浓度(HMC)要远低于十二胺, 十八胺更易在云母表面形成多层吸附, 证明烷基伯胺的碳链越长, 其对云母表面疏水性改善的能力越强. 实验结果与理论计算结果吻合良好.

关键词: 云母, 吸附, 疏水性, 原子力显微镜, 分子动力学模拟

Abstract: The adsorption of surfactants on mineral surface has a great influence on the solid hydrophobicity and flotation behavior. The relationship between the hydrocarbon tail length of the primary alkylamines and muscovite hydrophobicity was investigated by contact angle measurement, atomic force microscopy (AFM), density functional theory (DFT), and molecular dynamics (MD) simulation. By comparing the oxygen density and the hydrogen bonds number profile, we observed that the formed hydrogen bonds for each water molecule on the interface between hydrocarbon tails and the water phase were fewer than that in the bulk. Additionally, the muscovite that absorbed alkylamines transformed from a hydrophilic surface to hydrophobic one. We also found that the octadecylamine (ODA)-absorbed muscovite surface was more hydrophobic than the dodecylamine (DDA)-absorbed surface while they were both in a monolayer state. Furthermore, because octadecylamine has a much lower hemi-micelle concentration (HMC) than dodecylamine, it forms multilayer more easily, meaning that the primary alkylamine with longer hydrocarbon tail is a better choice for the hydrophobicity enhancement of muscovite surface. The experimental results are in good agreement with theoretical calculations.

Key words: Muscovite, Adsorption, Hydrophobicity, Atomic force microscopy, Molecular dynamics simulation

MSC2000: 

  • O647