Treatment of produced water in oil fields has become a tough challenge for oil producers. Nanofiltration, a promising method for water treatment, has been proposed as a solution. The phase inversion technique was used for the synthesis of nanofiltration membranes of polyethersulfone embedded with graphene oxide nanoparticles and polyethersulfone embedded with titanium nanoribbons. As a realistic situation, water samples taken from the oil field were filtered using synthetic membranes at an operating pressure of 0.3 MPa. Physiochemical properties such as water flux, membrane morphology, flux recovery ratio, pore size and hydrophilicity were investigated. Additionally, filtration efficiency for removal of constituent ions, oil traces in water removal, and fouling tendency were evaluated. The constituent ions of produced water act as the scaling agent which threatens the blocking of the reservoir bores of the disposal wells. Adding graphene oxide (GO) and titanium nanoribbons (TNR) to polyethersulfone (PES) enhanced filtration efficiency, water flux, and anti-fouling properties while also boosting hydrophilicity and porosity. The PES-0.7GO membrane has the best filtering performance, followed by the PES-0.7TNR and pure-PES membranes, with chloride salt rejection rates of 81%, 78%, and 35%; oil rejection rates of 88%, 85%, and 71%; and water fluxes of 85, 82, and 42.5 kg/m2 h, respectively. Because of its higher hydrophilicity and physicochemical qualities, the PES-0.7GO membrane outperformed the PES-0.7TNR membrane. Nanofiltration membranes embedded with nanomaterial described in this work revealed encouraging long-term performance for oil-in-water trace separation and scaling agent removal.

A series of nonionic surfactants were synthesized from gallic acid and polyethylene glycols with different molecular weights. Chemical structures of the surfactants were confirmed using elemental analysis, infrared and nuclear magnetic resonance ( 1 H-NMR) spectroscopy. Surface activities of the surfactants in their solutions were determined by surface tension measurements. Increasing the polyethylene glycol chain length increased the surface activity of the surfactants in solutions. Measurements of interfacial tension between surfactants solutions and substrates with different polarity showed that the type of substrates plays functioning role on the interfacial properties. Thermodynamic properties of adsorption and micellization processes showed their tendency towards adsorption at solution interface and micellization in their solutions. Results showed reasonable surface activities compared to conventional nonionic surfactants.

Nanofiltration methods were used and evaluated for strontium removal from wastewater. The phase inversion method was used to create a variety of polyethersulfone (PES)/TiO2 nanoribbons (TNRs)–multi-walled carbon nanotubes (MWCNTs) membranes with varied ratios of TNR-MWCNT nanocomposite. The hydrothermal technique was applied to synthesize the nanocomposite (TNRs-MWCNTs), which was then followed by chemical vapor deposition (CVD). The synthesized membranes were characterized by scanning electron microscopy (SEM), transmission electron microscopy, and FTIR. TNR macrovoids are employed as a support for the MWCNT growth catalyst, resulting in a TNR-MWCNT network composite. The hydrophilicity, mechanical properties, porosity, filtration efficiency of the strontium-containing samples, water flux, and fouling tendency were used to assess the performance of the synthesized membranes. The effect of feed water temperature on water flux was investigated as well as its effect on salt rejection. As the temperature increased from 30 to 90 °C, the salt rejection decreased from 96.6 to 82% for the optimized 0.7 PES/TNR-MWCNT membrane, whereas the water flux increased to ≈150 kg/m2. h. Double successive filtration was evaluated for its high efficiency of 1000 ppm strontium removal, which reached 82.4%.

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