高等学校化学学报 ›› 2023, Vol. 44 ›› Issue (11): 20230316.doi: 10.7503/cjcu20230316

• 物理化学 • 上一篇    下一篇

水-短链醇二元溶液的表面吸附

于先超1, 亓文帅1, 邓全花2, 侯万国1,3()   

  1. 1.山东大学胶体与界面化学教育部重点实验室
    2.化学与化工学院
    3.国家胶体材料工程技术研究中心, 济南 250100
  • 收稿日期:2023-07-05 出版日期:2023-11-10 发布日期:2023-09-11
  • 通讯作者: 侯万国 E-mail:wghou@sdu.edu.cn
  • 基金资助:
    国家自然科学基金(22272088)

Surface Adsorption of Water-alcohol Binary Solutions

YU Xianchao1, QI Wenshuai1, DENG Quanhua2, HOU Wanguo1,3()   

  1. 1.Key Laboratory of Colloid & Interface Chemistry,Ministry of Education
    2.School of Chemistry and Chemical Engineering
    3.National Engineering Technology Research Center of Colloidal Materials,Shandong University,Jinan 250100,China
  • Received:2023-07-05 Online:2023-11-10 Published:2023-09-11
  • Contact: HOU Wanguo E-mail:wghou@sdu.edu.cn
  • Supported by:
    the National Natural Science Foundation of China(22272088)

摘要:

基于表面聚集吸附(SAA)模型和Gibbs吸附微分方程, 建立了二元液体混合物Gibbs表面过剩(Γ2)和吸附层厚度(τ)代数方程, 可在全浓度范围内预测Γ2τ随体相组成(如组分2的摩尔分数x2,b)的变化. 采用所建立的模型, 研究了水(组分1)-短链醇(组分2)二元溶液的表面吸附行为, 其在水表面的吸附趋势按甲醇、 乙醇、 异丙醇、 正丙醇和叔丁醇的顺序依次增强, 与其疏水性增强趋势一致, 且其Γ2τ在低x2,b区均依次增大, 而在高x2,b区均依次减小, 是短链醇间吸附趋势和分子尺寸的差异所致. 对于给定的短链醇体系, 随着x2,b的增大, Γ2先急剧增大然后降低, 呈现一个最大值, 而其τ持续降低.

关键词: 液体混合物, 表面吸附, 表面聚集, 吸附层厚度, 热力学模型

Abstract:

Algebraic equations of the Gibbs surface excess(Γ2) and adsorption layer thickness(τ) were developed for binary liquid mixtures based on the surface aggregation adsorption(SAA) model and the Gibbs differential equation, which can predict the change of Γ2 and τ with the bulk composition(such as the molar fraction of component 2, x2,b) in the whole concentration range. The model equations were used to investigate the surface adsorption of water(1)-alcohol(2) binary solutions. The alcohols involved include methanol(MeOH), ethanol(EtOH), iso-propanol(iPrOH), n-propanol(nPrOH), and tert-butanol(tBuOH). It was found that their adsorption trend on the water surface increases in turn, consistent with the enhancement trend of their hydrophobicity. Their Γ2 and τ increase in turn in the low x2,b region, while decrease in turn in the high x2,b region, which arise from the differences in adsorption trend and molecular size between alcohols. In addition, for a given alcohol system, with an increase in x2,b from 0 to 1, its Γ2 initially sharply increases and then decreases, showing a maximum, but its τ exhibits a continuous reduction. This work provides a better understanding of the surface adsorption behavior of water-alcohol liquid mixtures.

Key words: Liquid mixture, Surface adsorption, Surface aggregation, Adsorption layer thickness, Thermodynamic model

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