The development of effective strategies for oil/water separation is a major global concern in protecting the ecological balance, human health and conservation of the limited water resources considering the rapid increase in industrialization and climate changes. Specifically, novel materials with special wettability properties such as superhydrophobic materials have been designed and synthesized for effective separation of oil and water. Unfortunately, these materials exhibit high oil affinity that results in fouling or blockage thus affecting the separation efficiency. This may further result in secondary pollution during the treatment of oil-contaminated materials.
Recently, different strategies for fabrication of the super-wetting water-loving materials have been proposed in response to the high demand for highly efficient oil/water separation. Specifically, chemical oxidation is increasingly becoming popular due to its easy scalability, low cost, and good corrosion resistance and mechanical properties. Additionally, surface modification has been proposed to induce antifouling property on the nanostructured layers. Presently, the interest in zwitterionic materials has been successfully used to enhance the fouling resistance of organic membranes during the oil and water separation. However, the cleaning of oil fouling in oil/water separation by grafting zwitterionic polymers coatings onto metal membrane surfaces have not been fully explored.
To this note, Sichuan University researchers: Huaqiang He, Housheng Jiang, Chen Chen, Like Ouyang, Wei Jiang and Shaojun Yuan synthesized a novel poly (sulfobetaine methacrylate) @ Cu (OH)2 nanoneedle array ([email protected]) coated copper meshes. The zwitterionic coated membrane was fabricated using chemical oxidation and surface-initiated free-radical polymerization methods for efficient water/oil separation. Various techniques including scanning electron microscopy were used to characterize the as-synthesized [email protected] coated mesh membranes. The work is currently published in the journal, ACS Sustainable Chemistry & Engineering.
The as-synthesized membrane exhibited highly efficient separation capabilities for different oil/water mixtures, oil field wastewaters among others. For instance, the water fluxes went as high as 80kL.h-1.m-2 and 10kL.h-1.m-2 for different oil/water mixtures and oil/water emulsion of oilfield wastewater respectively. Consequently, the demonstrated excellent antifouling ability ensured ease of cleaning, durability and good stability that favored the recycling of the as-synthesized [email protected] membrane.
The high superhydrophilic, underwater superoleophobic and antifouling properties of the mesh surface was attributed to the nano/micro-dual structure and zwitterionic PSBMA brushes. This also included the synergetic effect of surface roughness and hydration ability induced by the zwitterionic PSBMA brushes and the copper meshes. Furthermore, the polymeric layers of the CHNNA-covered meshes protected the substrate from spoilage thus ensuring lasting structural and chemical stability. To assess the superiority of their superhydrophilic and underwater superoleophobic properties, it was necessary to expose the novel mesh to deionized water. As a result, the water contact angles of the coated mesh membranes remained unchanged as observed in the corresponding images, that confirmed the high durability and stability of the chemical grafted layers.
In summary, the newly developed zwitterionic [email protected] membrane exhibited excellent stability, durability and antifouling properties for efficient use in the separation of water and oil. Regarding the advantages, the presented membrane synthesis approach offers an alternative promising approach for developing new generation membranes for efficient water/oil separation.
He, H., Jiang, H., Chen, C., Ouyang, L., Jiang, W., & Yuan, S. (2019). Efficient Oil/Water Separation by Zwitterionic Poly (sulfobetaine methacrylate) @ Cu (OH)2 Nanoneedle Array-Coated Copper Meshes with Superwetting and Antifouling Properties. ACS Sustainable Chemistry & Engineering, 7(16), 13815-13826.Go To ACS Sustainable Chemistry & Engineering