Dynamic Membrane with a Polystyrene Surface Layer for Ultrafiltration of Spent Coolant Lubricant

Ultrafiltration membranes with a dynamic layer of polystyrene particles 55–72 nm in size were obtained on a hydrophilic polytetrafluoroethylene substrate. The results of scanning electron microscopy showed the formation of a layer of spherical particles on the membrane surface. After applying a layer of polystyrene to the surface of a polytetrafluoroethylene substrate, a decrease in the specific productivity of the membranes is observed, and an increase in the hydrophobicity of the surface layer of the membrane is revealed. The dynamic membrane was used to separate spent cutting fluid (coolant). The separation efficiency of the emulsion was evaluated by the removal of petroleum products and fatty acids. The retention capacity of the membrane for oil products from the spent emulsion was 95% with a specific productivity of 167 dm3 /(m2· hr), which is not inferior to the performance of commercial ultrafiltration membranes. The HPLC method was used to study the content of fatty acids in the emulsion and its filtrates. The retention capacity of the dynamic membrane for fatty acids was more than 68%.