Hydrogel-Coated Mesh for High-Efficiency, Ultra-Fast Oil-Water Separation

Abstract Fast and efficient oil-water separation is critical to resolving industrial wastewater, environmental protection, and oil spills. With the demand for oil continuing to grow and the global oil reserves being limited in supply, it becomes more important to be able to recover as much oil as possible. In this paper, a reinforced membrane made using a polyacrylamide (PAM) hydrogel solution was used to coat different copper mesh samples that have a variety of pore sizes. The wetting properties of membranes are characterized by the contact angle (CA) measurements, the permeability of bulk fluids, and the surface morphologies of the mesh before and after coating. Using a contact angle goniometer, it was found that the static underwater oil CA showed to be over 90° while the oil CA in air resulted in an angle below 15°. Since the oil CA in the air is less than the oil CA underwater, we can imply that the PAM hydrogel-coated mesh samples are superhydrophilic in the method of using an air-solid-liquid three-phase system. As the mesh pore size increases, the oil CA also increases. The difference in weight during the swelling period becomes larger with increasing mesh pore size up to approximately 2880 minutes. With the use of a long working distance microscope, it was found a uniform hydrogel coating resulted in smaller pore size and a rougher surface. It was found that the coated mesh after testing has less binding at the mesh joints compared to the coated mesh before testing. From this, it can be indicated that high swelling rates result from large aggregation near the mesh joints.