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BACKGROUND: Membrane distillation (MD) for desalination encounters significant hurdles as a result of pore wetting, leading to reduced permeate flux or deterioration in permeate quality over time. Therefore, membranes used in MD must be highly hydrophobic to prevent liquid from entering the pores and contaminating the permeate stream. In this study, a thin layer of MoS2‐TiO2 composite was coated using poly (DOPA) as an adhesive to enhance attachment. Two coating methods, interlinking and layering, were compared to determine the most effective method for forming a thin hydrophobic coating layer onto PVDF‐PES hollow fiber membrane. RESULTS: Interestingly, this study revealed that increasing the number of dipping cycles led to higher flux, defying conventional expectations. This unexpected outcome is likely to have resulted from the thicker coatings creating a more hydrophobic surface, reducing water molecule adhesion and preventing wetting. Consequently, the membrane demonstrated enhanced flux despite its increased thickness. Among the membranes tested, the MoS2‐TiO2/PVDF‐PES membrane coated using the layering method exhibited the best performance, leading to a flux of 2.06 kg m−2 h−1 and 99.99% salt rejection. This superior performance can also be attributed to the membrane's hydrophobic properties, evident in its water contact angle (WCA) of 99°. By contrast, the interlinking method resulted in lower performance, with a permeate flux of 1.70 kg m−2 h−1 and 99.96% salt rejection, which is likely to have resulted from its lower WCA of 86°. CONCLUSION: The findings from this study suggest that the coating method has the potential to greatly improve membrane distillation performance through wettability modification rather than altering membrane porosity. © 2024 Society of Chemical Industry (SCI). [ABSTRACT FROM AUTHOR]

Adsorptive-photocatalytic electrospun nanofiber membranes have received remarkable attention as they could provide an excellent solution for the effective treatment of wastewater. However, the mechanical properties of nanofiber have limited their use in pressure-driven filtration applications. In this study, dual-layered MoS2/PAN-CA adsorptive-photocatalytic-based membranes have been successfully fabricated using molybdenum disulphide/polyacrylonitrile (MoS2/PAN) nanofiber coated porous cellulose acetate (CA) membranes. The fabricated CA membranes were coated with electrospun MoS2/PAN nanofiber via the electrospinning technique. Subsequently, hot-pressed treatment was applied to the fabricated membrane to form a stronger attachment between the CA and MoS2/PAN nanofiber layers. The physicochemical properties of the fabricated membranes were characterised using scanning electron microscopy (SEM), energy dispersive X-ray (EDX), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analyzer (TGA), water contact angle (WAC), porosity analysis, and tensile strength test. In addition, the membrane separation performance of the fabricated nanofiber membranes was evaluated in terms of water flux and contaminant rejection using a self-assembled cross-flow filtration system. The MoS2/PAN-CA membrane demonstrated improved physicochemical and structural properties where WAC, porosity and mechanical strength increased up to 38% (44.0°), 25% (55%) and 26% (32.1 MPa), respectively, as compared to pristine CA membrane. Upon hot-pressed treatment at a temperature of 120 °C, pure water flux of MoS2/PAN-CA membrane improved by 28% to 36.3 Lm−2 h−1. These improved properties of dual-layered adsorptive-photocatalytic MoS2/PAN-CA membranes recommend it as a potential membrane material to treat various pollutants in water and wastewater. [ABSTRACT FROM AUTHOR]

BACKGROUND: In this work, a series of graphene oxide–polyethersulfone (GO–PES) composite flat sheet (FS) and hollow fiber (HF) membranes were fabricated by blending 0.5 and 1.0 wt% of GO into the PES matrix and utilized for oil–water separation. GO was first prepared and characterized by using Fourier‐transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), X‐ray diffraction (XRD) and thermogravimetric analysis (TGA) before being used as membrane fillers. RESULTS: Interestingly, although similar dope composition was used for the fabrication of HF and FS membranes, their morphology and pore size varied significantly owing to the way the membranes were fabricated. Significant enhancement of hydrophilicity was observed for both composite FS and HF membranes, where the water contact angle value decreased from 74.8° to 42.2° and 71.4° to 49.8°, respectively. The flux of the composite membranes increased up to 150% of the bare membranes especially when 1.0 wt% of GO was added. Although higher oil rejection (~99%) was observed for HF membranes that possess smaller pores, the permeation flux was maintained due to the improved flow dynamic. Lower oil rejection (up to 50%) was observed for FS membranes, which might be due to its big pore sizes particularly at the bottom surface. As more oil droplets formed on the membrane surface and prevented water molecules to pass through the membrane, fouling might occur rapidly. CONCLUSIONS: The results obtained in this work suggest that surface hydrophilicity, pore size of membranes and oil–water separation performances was greatly affected by membrane shape. Owing to many advantages of HF membranes, this type of membrane has great potential for commercial applications. © 2020 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

In this work, the surface of a PVDF-based hollow fiber membrane was modified by coating MoS 2 -TiO 2 to improve the performance of membrane distillation (MD). The MoS 2 -TiO 2 was first synthesized at different ratios using a one-step hydrothermal process. Then, the PVDF-based hollow fiber membrane was spun at various air gaps and PES was also added as an additive. As 5M5T (50 wt% MoS 2 and 50 wt% TiO 2) possessed better physicochemical properties and narrow band gap, the 5M5T was mixed with trichloro(octadecyl)silane in (OTS) at various loading to form a dip-coating solution. The PP20 membrane (PVDF + PES) spun at a 20 cm air gap was used as a support for MD due to its high porosity and low membrane thickness. It was observed that the contact angle of the MoS 2 -TiO 2 /PP20 membrane increased significantly to 136.8 ± 2.33° when the membrane was coated with 0.2% of 5M5T MoS 2 -TiO 2. The MD performances were investigated via an in-house MD system. The results revealed that the performances of MoS 2 -TiO 2 /PP20 membranes were much higher than previously reported membranes due to their enhanced hydrophobicity and porosity properties. It was observed that a higher operating temperature could elevate the permeate flux up to 23.3 kg·m−2·h−1, but less than 0.1% changes in the rejection rate. The results obtained in this work suggest that the MoS 2 -TiO 2 coated on the PVDF-based membrane can overcomes the typical permeability/rejection rate trade-off effect, which can play a significant role in enhancing MD performances. [Display omitted] • The surface of PVDF-based hollow fibre membrane was modified using various loading of MoS2-TiO2. • The coated PVDF-based membrane possesses a higher contact angle and better hydrophobicity. • The permeate flux of coated PVDF membranes was higher due to their enhanced hydrophobicity and porosity. • The permeate flux increased significantly with minimal changes in salt rejection rate at various operating temperature. [ABSTRACT FROM AUTHOR]