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The effective treatment of industrial oil/water emulsion before discharging into the receiving bodies is essential to prevent environmental pollution and its negative impacts on human health. The nanomaterial-incorporated nanocomposite membranes are touted as suitable candidates for removing oil contaminants from water. The selection of nanomaterial in nanocomposite membranes is crucial to fit the intended application. In this study, the performance of four different nanomaterials, i.e., metal-organic frameworks-71 (MOF-71), silicon dioxide (SiO 2), activated carbon (AC), and halloysite nanotubes (HNTs), were used as the nanofiller of membranes. The resultant membranes were characterized by FESEM, AFM, water contact angle, and FTIR analysis. The membrane performance was examined in pure water flux (PWF) and oil/water emulsion rejection studies. The enhancement of PWF in SiO 2 , HNTs, MOF-71, and AC-based PEI/PVP composite membranes compared to neat PEI/PVP membranes was 33.33%, 59.25%, 70.37%, and 77.77%, respectively. The PEI/PVP/MOF-71 and PEI/PVP/AC membranes exhibited the best performance for PWF and oil/water rejection. Engine oil/water, hexane/water, and toluene/water % rejection of PEI/PVP/AC membrane was found to be 91.98%, 90.55%, and 93.74%, respectively, significantly higher than the neat PEI/PVP membrane. Furthermore, the nanomaterials-incorporated membrane showed better antifouling properties than the neat PEI/PVP membrane due to enhanced hydrophilicity. The MOF-71 and AC nanomaterials-based PEI membranes exhibited good oil/water emulsions separation due to their reliable adsorption capacity and improved fouling resistance than HNTs and SiO 2 nanomaterials incorporated membranes, which could have a wide range of membrane-based water treatment applications. [Display omitted] • Fabricated PEI composite membranes by incorporating MOF-71, HNTs, SiO 2 and AC nanomaterials. • PEI composite membranes showed enhanced antifouling properties than neat PEI/PVP. • MOF-71 and AC based membrane showed higher oil/water flux and rejection than neat PEI/PVP membrane. • PEI/PVP/AC membrane exhibited 91.98% rejection for engine oil/water emulsions. [ABSTRACT FROM AUTHOR]

Today, one of the most imortant environmental problems is the treatment of industrial wastewaters containing heavy metal ions and salts. In this research, thin-film nanocomposite (TFN) membranes were developed through incorporation of modified titanate nanotube (TNT) and halloysite nanotube (HNT) into the polyamide (PA) active layer to improve the performance of the NF membranes. At first, the internal surface of the nanotubes was coated with different polymers to lessen the inner diameter of the nanotubes. Then, the inner surface coated nanotubes were magnetized through placing Fe 3 O 4 on their outer surface. In case of magnetized nanotubes, the fabrication of the membranes was done in the absence and in the presence of the external magnetic field, which made the nanotubes to align in a regular pattern across the PA layer, smoothing the membranes' surface and lowering the contact angle. It is expected that the magnetized nanotubes can make suitable arrangement in the structure of thin layer in the presence of the magnetic field and show better performance. The nanotubes act as the channels for water transport and in case of inner coated nanotubes, reject more ions through the steric hindrance. The pure water permeation of the membranes, modified with polystyrene inner coated TNT and HNT increased by 71.23% and 80.27%, respectively compared to the pristine TFC membrane without any significant changes in the rejection of Na+ and Cu2+; a suitable trade-off between the permeation and the ion rejection. In addition, the membranes modified by magnetized polyaniline inner coated TNT and HNT showed 36.24% and 75.62% more water permeation compared to the pristine TFC membranes while the rejections of Na+ and Cu2+ have not been changed remarkably. The results of this research showed that inner coating and magnetization of the nanotubes can be considered as a novel method to enhance the efficiency of TFN membranes for wastewaters treatment. [Display omitted] • Performance of TFN NF membranes was improved through embedding magnetic internally-coated nanotubes. • The nanotubes in the PA layer of TFN membranes act as the channels for water transfer. • The internal coating of the nanotube controls the passage of the ions and improved the rejection. • The magnetization of the nanotube enhanced their distribution in PA layer that lessens the thickness of the layer. • The incorporation of modified nanotubes can dominate the trade off between permeation and ion rejection of TFN membranes. [ABSTRACT FROM AUTHOR]

The high concentrations of heavy metal ions in industrial effluents are one of the most challenging wastewaters to deal with. In this study and in order to change the inner diameter of the halloysite nanotubes (HNT), their internal surface was coated by different polymers (polydopamine, polyaniline and polystyrene) and then, the modified nanotubes were incorporated in the polyamide thin film NF membrane for the treatment of metal ions solutions. Fourier Transform Infrared Spectroscopy (FTIR), X-ray diffraction (XRD) and Brunauer-Emmett-Teller (BET) studies indicated that the internal coating was successful. Furthermore, the neat and modified nanofiltration (NF) membranes were characterized in terms of morphology, contact angle, water flux and metal ion rejection. The modified membranes displayed lower contact angle values (29.4% reduction) that can be linked to the hydrophilic groups in the structure of the coated polymers and the smoother surface of the thin film nanocomposite (TFN) membrane. In addition, the permeation fluxes of the modified membranes were improved significantly (33.4% improvement) without any major reduction in their ion rejection; that shows HNTs act as the channels to transfer water through the membrane structure while the coating of the inner surface of HNT reduces the size of the channel and makes more repulsion and steric hindrance for the ion to pass through the nanotubes. Among the fabricated membranes, the NF membrane with 0.05 wt% polystyrene-coated HNT showed the lowest contact angle (55.30o) and the highest water permeation flux (27.51 L m-2 hr-1), compared to the neat TFC membrane (15.26 L m-2 hr-1) and the NF membrane with 0.05 wt% unmodified HNT (20.62 L m-2 hr-1). [Display omitted] • The internal surface of HNTs was coated with different polymers through a novel polymerization method. • Polydopamine, polyaniline and polystyrene were used as the polymer for coating. • The modified HNTs were used to improve the performance of TFN NF membrane. • HNTs act as the channels to transfer water through the membrane structure. • The permeations of the TFN membranes with modified HNTs were improved significantly without any reduction in the rejection. [ABSTRACT FROM AUTHOR]

• Thermal stable SPEEK membrane was fabricated with halloysite nanoclay and functionalized GO nanocomposites. • The silane and sulfonic acid group in the nanocomposite SPEEK membrane increased IEC and low methanol permeability. • The nanoclay and fGO membranes have shown significant proton conductivity and power density than pristine SPEEK membrane. Membrane-based fuel cells, particularly methanol-based fuel cells, are thriving areas with high efficiency, less material consumption, and low emission of pollutants. But commercial membranes have less thermal withstanding ability and high cost, so alternative polymeric membranes have been developed with desired properties to overcome this issue. The SPEEK membrane was fabricated with halloysite nanoclay and functionalized graphene oxide (f-GO) nanocomposites at various concentrations via dry phase inversion. The sulfonic acid group in the SPEEK and silane functionalization of GO enhanced the Ion exchange capacity from 0.22 to 0.35 meq/g which enhances the proton conductivity. Furthermore, the thermal stability and hydrophilicity of the pristine SPEEK membrane were reformed with addition of halloysite nanoclay and f-GO in SPEEK membrane. The presence of nanocomposite on the surface of the SPEEK membranes was confirmed via scanning electron microscope (SEM) analysis. The 3 wt% halloysite nanoclay and 2 wt% of f-GO composite membrane was hold the 0.47 mS cm−1 of proton conductivity and 72.2 mW cm−2 of power density, whereas pristine SPEEK membrane was 0.31 mS cm−1 and 28 mW cm−2, respectively. The 3 wt% halloysite incorporated SPEEK membrane and 1.5 wt% f-GO incorporated SPEEK membrane was shown better proton conductivity, which act as a prominent membrane for direct methanol fuel cell (DMFC) applications. [ABSTRACT FROM AUTHOR]