Zhang Jialu, Peng Kaiming, Xu Zhi-Kang, Xiong Yongjiao, Liu Jia, Cai Chen, Huang Xiangfeng
State Key Laboratory of Pollution Control and Resource Reuse, Ministry of Education Key Laboratory of Yangtze River Water Environment, Shanghai Institute of Pollution Control and Ecological Security, College of Environmental Science and Engineering, Tongji University, No.1239 Siping Road, Shanghai 200092, PR China.
State Key Laboratory of Pollution Control and Resource Reuse, Ministry of Education Key Laboratory of Yangtze River Water Environment, Shanghai Institute of Pollution Control and Ecological Security, College of Environmental Science and Engineering, Tongji University, No.1239 Siping Road, Shanghai 200092, PR China; Institute of Carbon Neutrality, Tongji University, No.1239 Siping Road, Shanghai 200092, PR China.
Adv Colloid Interface Sci. 2023 Sep;319:102971. doi: 10.1016/j.cis.2023.102971. Epub 2023 Aug 2.
Membrane separation technology has significant advantages for treating oil-in-water emulsions. Understanding the evolution of oil droplets could reveal the interfacial and colloidal interactions, facilitate the design of advanced membranes, and improve the separation performances. This review on the characteristic behavior and evolution of oil droplets focuses on the advanced analytical techniques, and the subsequent fouling as well as demulsification effects during membrane separation. A detailed introduction is provided on microscopic observations and numerical simulations of the dynamic evolution of oil droplets, featuring real-time in-situ visualization and accurate reconstruction, respectively. Characteristic behaviors of these oil droplets include attachment, pinning, wetting, spreading, blockage, intrusion, coalescence, and detachment, which have been quantified by specific proposed parameters and criteria. The fouling process can be evaluated using Hermia and resistance models. The related adhesion force and intrusion pressure as well as droplet-droplet/membrane interfacial interactions can be accurately quantified using various force analysis methods and advanced force measurement techniques. It is encouraging to note that oil coalescence has been achieved through various effects such as electrostatic interactions, mechanical actions, Laplace pressure/surface free energy gradients, and synergistic effects on functional membranes. When oil droplets become destabilized and coalesce into larger ones, the functional membranes can overcome the limitations of size-sieving effect to attain higher separation efficiency. This not only bypasses the trade-off between permeability and rejection, but also significantly reduces membrane fouling. Finally, the challenges and potential research directions in membrane separation are proposed. We hope this review will support the engineering of advanced materials for oil/water separation and research on interface science in general.
膜分离技术在处理水包油乳液方面具有显著优势。了解油滴的演变可以揭示界面和胶体相互作用，有助于先进膜的设计，并提高分离性能。这篇关于油滴特征行为和演变的综述重点关注先进的分析技术，以及膜分离过程中随后的污染和破乳效果。分别详细介绍了油滴动态演变的微观观察和数值模拟，其特点分别是实时原位可视化和精确重建。这些油滴的特征行为包括附着、钉扎、润湿、铺展、堵塞、侵入、聚结和脱离，已通过特定提出的参数和标准进行了量化。污染过程可以使用赫米亚模型和阻力模型进行评估。使用各种力分析方法和先进的力测量技术可以准确量化相关的粘附力和侵入压力以及液滴 - 液滴/膜界面相互作用。值得注意的是，通过静电相互作用、机械作用、拉普拉斯压力/表面自由能梯度以及对功能膜的协同作用等各种效应已经实现了油滴的聚结。当油滴变得不稳定并聚结成更大的油滴时，功能膜可以克服尺寸筛分效应的限制以获得更高的分离效率。这不仅绕过了渗透率和截留率之间的权衡，而且还显著减少了膜污染。最后，提出了膜分离中的挑战和潜在研究方向。我们希望这篇综述将支持用于油/水分离的先进材料的工程设计以及一般界面科学的研究。
