研究报告

  • 赵士雄,王智,王显胜,刘周,王新法,王小(亻毛).微/纳米颗粒表面能测定方法适用性研究[J].环境科学学报,2018,38(1):259-266

  • 微/纳米颗粒表面能测定方法适用性研究
  • Applicability of surface energy measurement methods for micro/nano-size particles
  • 基金项目:国家自然科学基金(No.51678331)
  • 作者
  • 单位
  • 赵士雄
  • 吉林大学水资源与水环境吉林省高等学校重点实验室, 长春 130021
  • 王智
  • 清华大学环境学院, 环境模拟与污染控制国家重点联合实验室, 北京 100084
  • 王显胜
  • 吉林大学水资源与水环境吉林省高等学校重点实验室, 长春 130021
  • 刘周
  • 吉林大学水资源与水环境吉林省高等学校重点实验室, 长春 130021
  • 王新法
  • 吉林大学水资源与水环境吉林省高等学校重点实验室, 长春 130021
  • 王小(亻毛)
  • 清华大学环境学院, 环境模拟与污染控制国家重点联合实验室, 北京 100084
  • 摘要:采用静态液滴法、柱毛细法、板毛细法3种方法,分别测定了水、正己烷、甲酰胺、二碘甲烷4种液体与TiO2(40 nm)、TiO2(100 nm)、Al2O3(200 nm)、高岭土(200~400nm)、Fe2O3(400~600 nm)、SiO2(20 μm)6种粒径微/纳米颗粒之间的接触角,确定了适用于不同颗粒粒径的接触角测定方法.在此基础之上,利用Young-Dupré方程计算了各微/纳米颗粒的表面能及各分项.结果表明:粒径较小的颗粒(如<200 nm)接触角的测定适合使用静态液滴法,而粒径较大的颗粒(如>600 nm)接触角的测定适合使用柱毛细法.粒径大小适中时(如200~600 nm),静态液滴法和柱毛细法都适用,测定结果差别普遍较小(≤ 11°),但二碘甲烷与Fe2O3(400~600 nm)之间的接触角利用不同方法测定结果相差可达14°.静态液滴法操作方便,但由于粗糙度的影响需要对接触角测定值进行修正.板毛细法测定接触角时,液体容易挥发,不易得到准确测量结果,不推荐使用.对全部6种测定的微/纳米颗粒,表面能的计算结果相差不大.表面能的3个分项中,范德华分量(γLW)与路易斯碱分量(γ-)的贡献最大,路易斯酸分量(γ+)的贡献很小,主要是因为在微/纳米颗粒-液体界面中,电子受体的反应活性较低.
  • Abstract:This study, the sessile drop method, column wicking method and layer wicking method were employed to measure the contact angles of water, hexane, formamide and diiodomethane on six micro/nano-size particles including TiO2(40 nm), TiO2(100 nm), Al2O3(200 nm), kaolin(200~400 nm), Fe2O3(400~600 nm) and SiO2(20 μm), based on which the most applicable measurement methods for the particular particles were determined. The Young-Dupré equation was adopted to calculate the respective surface energy and composing components. Results showed that the sessile drop method was more applicable for relatively smaller particles e.g. with sizes <200 nm, while the column wicking method fitted for relatively larger particles e.g. with sizes >600 nm instead. Both the sessile drop method and column wicking method were applicable for the micro/nano-size particles with sizes in between. The obtained results generally matched very well with difference in contact angles within 11°. However, the difference could be much bigger, especially for Fe2O3(400~600 nm) when diiodomethane was used (the difference value was 14°). The sessile drop method was easy to use but correction must be made to eliminate the effect of surface roughness. The layer wicking method would not be recommend as it failed to present credible results due to evaporation of the testing liquid during the measurement process. It turned out that the surface energies of the six micro/nano-size particles were similar. Among the three components of surface energy, the Lifshitz-van der Waals and the Lewis base components contributed the most, while the Lewis acid component contributed little because of the low abundance of electro-acceptors on the particle-liquid interface.

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