MoS2-TiO2 coated PVDF-based hollow fiber membranes for permeate flux enhancement in membrane distillation.

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]