Surface modification of PVDF membrane via layer-by-layer self-assembly of TiO2/V for enhanced photodegradation of emerging organic pollutants and the implication for wastewater remediation

Abstract

Herein, we present a novel polyvinylidene fluoride/vanadium-titanium dioxide (PVDF-TiO2/V) membranes prepared using LBL self-assembly. The membranes were tested for ultrafiltration of bovine serum albumin solution and photodegradation of SMX solution. The neat PVDF membrane was endowed with photocatalytic function due to the synergistic interaction of TiO2 and V. The structure and morphology of PVDF-TiO2/V membranes were characterized using a variety of techniques, showing that TiO2/V particles had been successfully integrated on the membrane surface. By increasing the number of TiO2/V layers, contact angle tests demonstrated that the membranes hydrophilicity has been significantly improved. The FTIR result demonstrated that the TiO2/V was affixed to the surface of the PVDF membrane by interfacial interactions. The thermal property of the PVDF membrane was also improved with the assembly of TiO2/V on the membrane surface. The PVDF-TiO2/V membranes maintained a high BSA rejection of 99.4 % and FRR of 97.4 % while showing a water flux up to 390.07 kg m-2h−1, which is ∼1.5 times higher than that of neat PVDF membrane. Specifically, the membranes were capable of degrading SMX under visible-light. The photocatalytic activity for SMX increased with the number of TiO2/V layers, attaining the highest value with four self-assembled TiO2/V layers. The reaction rate of the optimum membrane was 11.57-fold compared to the neat membrane under visible-light. Furthermore, 95.9 % degradation efficiency was achieved, even after six cycles. More importantly, BPA, MO, and MB could be photodegraded using the PVDF-TiO2/V membranes. Compared to using bulk or powdered photocatalysts, the PVDF-TiO2/V membrane is more practical and promising for wastewater remediation due to its many advantages including better long-term stability, ability to endure pollutant degradation, low cost, and environmentally friendly.