Preparation and enduring effect oil-water separation performance of water-based superhydrophilic anti-fouling composite mesh membrane

Oily sewage is ubiquitous in the petrochemical industry, machinery manufacturing and other fields. Direct discharge not only wastes water and oil resources, pollutes the ecological environment, but also affects the survival and health of human beings and other organisms. The traditional oil-water separation method has strong limitations, such as poor economy and low separation efficiency. Based on 316 stainless mesh, a superhydrophilic/underwater oleophobic membrane that was resistant to long-term water immersion and oil pollution was developed. The water-based acrylic acid resin and water-based epoxy topcoat resin were selected as the binder, and the substrate was pretreated with phytic acid. The superhydrophilic/underwater oleophobic membrane coated with water-based coating was prepared using a one-step spraying method. It is found that the separation efficiency of wastewater with different oils can reach more than 98%, the water flux can reach more than 14 000 L/(m2·h·bar), and the intrusion pressure of oil is 4.65 kPa. After 50 cycles of separating wastewater with N-hexane, the separation efficiency of the membrane can still reach more than 98%. After 180 days of water immersion, the membrane still maintains superhydrophilicity with a water flux of more than 6 500 L/(m2·h·bar). After adding a small amount of surfactant of sodium dodecyl sulfate, the water flux of the membrane decreases by less than 50% after 50 pollution and cleaning cycles. This study provides technical references for the development and preparation of superhydrophilic separation membranes in the field of refined oily wastewater treatment. © 2023 Beijing University of Aeronautics and Astronautics (BUAA). All rights reserved.