Nanostructure-Based Oil–Water Separation: Mechanism and Status

Abstract

Flexible and effective methods for oil–water separation are crucial for reducing pollutant emissions and safeguarding water and fuel resources. In recent years, there has been growing interest in fundamental research and engineering applications related to water and fuel purification, especially oil–water separation. To date, filter materials with special wetting characteristics have been widely used in oil–water separation. Nanostructured materials are one of the most attractive candidates for next-generation oil–water separation. This review systematically summarizes the mechanisms and current status of oil–water separation using nanostructured materials. Basically, this can be achieved by using nanostructured materials with specific wettability and nanostructures. Here, we provide a detailed discussion of two general approaches and their filtration mechanisms: (1) the selective filtration technique, based on specific surface wettability, which allows only oil or water to penetrate while blocking impurities; (2) the absorption technique, employing porous sponges, fibers, or aerogels, which selectively absorbs impure oil or water droplets. Furthermore, the main failure modes are discussed in this review. The purposes of this article are: (1) to summarize the methods of oil–water separation by nanotechnology; (2) to raise the level of environmental protection consciousness of water pollution by using nanotechnology; (3) to tease out the features of different approaches and provide a pivotal theoretical basis to optimize the performance of filtering materials. Several approaches for oil and water separation are compared. Furthermore, the principle and application scope of each method are introduced.

Antibacterial Nano-Architected CS/PVA/s-triazine Hydrogel-Coated Mesh for Oil/Water Emulsion Separation

“…Furthermore, the hydrogel’s propensity to swell in the presence of water can alter the interfacial tension dynamics between the oil and water phases, promoting emulsion breaking. This swelling effect creates a more tortuous path for the oil droplets, further enhancing separation efficiency. , …”

“…This swelling effect creates a more tortuous path for the oil droplets, further enhancing separation efficiency. 49,50 For continuous filtration testing, the water flux and separation efficiency of the CPTM showed minor variation, remaining largely maintained after 50 filtration cycles (Figure S13). The slight decrease in the water flux over repeated use may be due to the gradual fouling of the mesh.…”

Carwash Oily Wastewater Separated by Ultrafiltration

“…Their content is most often in the range of 10-50 mg/L; nevertheless, concentrations above 500 mg/L also occur [4]. This is a very important challenge for researchers since effluents containing such amounts of oil contaminants may destroy the ecological environment and seriously endanger human health [5]. Therefore, the treatment of oily wastewater is necessary.…”

“…Such changes in the properties of membranes often occur very slowly; hence, they can only be observed after several weeks of wastewater filtration [20]. Meanwhile, in many publications, the wastewater treatment process is often presented on the basis of short tests, which does not allow for a proper assessment of the possibilities of industrial application [5]. For this reason, in the present work, multi-week tests on the separation of wastewater from a car wash were carried out.…”