Synthesis, characterization and performance studies of polysulfone/bentonite nanoparticles mixed-matrix ultra-filtration membranes using oil field produced water

• Purification of oil field produced water using PSf–bentonite UF membrane.
• Performance comparison of PSf–bentonite and PSf–silica UF membrane.
• Viscoelastic properties of membrane casting solutions.
• SEM, EDS, AFM, FTIR analysis of membrane.
• Permeate flux enhancement.

The present paper deals with the performance studies of newly formulated polysulfone–bentonite ultra-filtration membrane for the purification of oily produced water and the results were compared with standard polysulfone–silica membrane. Membranes were prepared via phase inversion technique by blending silica and bentonite nanoparticles separately with polysulfone and N-methyl-2-pyrrolidone solution. Particle size distribution, specific surface area, morphology, FTIR, elemental analysis and cation exchange capacity of silica and bentonite nanoparticles were determined. Viscoelastic properties of membrane casting solution were measured to determine the maximum applied strain (i.e., ⩽70 s−1) to avoid structural degradation while casting. The surface morphology of membranes was analyzed by field emission scanning electron microscopy and atomic force microscope. Porosity, contact angle and equilibrium water content of individual membrane was also determined. The membranes were subjected to ultra-filtration characterization such as compaction factor, hydraulic permeability, pure water flux, percent oil rejection and molecular weight cut-off for performance studies. Finally, membrane performance of silica and bentonite blended polysulfone membranes was compared by measuring permeate flux, flux declination rate and oil rejection. An improved performance of polysulfone–bentonite membranes was obtained for desired percent rejection over polysulfone–silica membrane.