Preparation of a polystyrene-based super-hydrophilic mesh and evaluation of its oil/water separation performance

Polystyrene rendered hydrophilic by sulfonation was coated onto a nylon mesh by non-solvent-induced phase separation to obtain super-wettability and construct a stable super-hydrophilic/underwater super-oleophobic mesh for oil/water separation. Various oil/water mixtures were separated with efficiencies of similar to 100%, and the above mesh was shown to feature the advantages of low efficiency loss over 100 cycles, a high flux of similar to 25,000 L m(-)(2) h(-1) , stable continuous separation, and high resistance to fouling, which allowed the effective separation of mixtures containing pollutants, such as salts and acids. The splitting of oil droplets due to laminar motion at the oil/water interface was identified as a major factor influencing separation efficiency. Flux through the mesh greatly increased when salt solutions were used as the water phase, and the mechanism of this increase was investigated. Wettability was suggested to be affected by spontaneous interfacial chemical reactions, and an equation describing this influence was established. The obtained mechanistic insights provide a theoretical basis for enhancing membrane properties, and the developed membrane is concluded to be well suited for diverse oil/water separation applications and is of great value for novel green separation technologies.