Song Chen, Rutledge Gregory C
Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States.
Langmuir. 2023 Aug 15;39(32):11468-11480. doi: 10.1021/acs.langmuir.3c01477. Epub 2023 Aug 4.
The removal of emulsified oils from water has always been a challenge due to the kinetic stability resulting from the small droplet size and the presence of stabilizing agents. Membrane technology can treat such mixtures, but fouling of the membrane leads to dramatic reductions in the process capacity. Liquid-infused membranes (LIMs) can potentially resolve the issue of fouling. However, their low permeate flux compared with conventional hydrophilic membranes remains a limitation. To gain insight into the mechanism of transport, we use 3D images acquired by confocal laser scanning microscopy (CLSM) to reconstruct the sequence of events occurring during startup and operation of the LIM for removal of dispersed oil from oil-in-water emulsions. We find evidence for coalescence of oil droplets on the surface of and formation of oil channels within the LIM. Using image analysis, we find that the rate at which oil channels are formed within the membrane and the number of channels ultimately govern the permeate flux of oil through the LIMs. Oil concentration in the feed affects the rate of coalescence of oil on the surface of the LIM, which, in turn, affects the channel formation dynamics. The channel formation dynamics also depend on the viscosity of the infused liquid and the operating pressure. A higher affinity to the pore wall for infused liquid than permeating liquid is essential to antifouling behavior. Overall, this work offers insight into the selective permeation of a dispersed liquid phase through a LIM.
由于小液滴尺寸和稳定剂的存在导致的动力学稳定性，从水中去除乳化油一直是一项挑战。膜技术可以处理此类混合物，但膜污染会导致处理能力大幅下降。注液膜（LIMs）有可能解决污染问题。然而，与传统亲水性膜相比，它们的低渗透通量仍然是一个限制。为了深入了解传输机制，我们使用共聚焦激光扫描显微镜（CLSM）获取的三维图像来重建在LIM启动和运行过程中发生的一系列事件，以从水包油乳液中去除分散油。我们发现了油滴在LIM表面聚结以及在LIM内部形成油通道的证据。通过图像分析，我们发现膜内油通道形成的速率和通道数量最终决定了油通过LIMs的渗透通量。进料中的油浓度会影响油在LIM表面的聚结速率，进而影响通道形成动力学。通道形成动力学还取决于注入液体的粘度和操作压力。注入液体对孔壁的亲和力高于渗透液体对于防污行为至关重要。总体而言，这项工作为分散液相通过LIM的选择性渗透提供了见解。
