Development and characterization of polyvinylidene fluoride/graphene mixed matrix membranes for high-rejection treatment of textile wastewater
摘要
Membrane distillation (MD) is a promising technology for the sustainable treatment of textile industry wastewater. This study investigates the development and performance of polyvinylidene fluoride (PVDF) mixed-matrix membranes (MMMs) incorporating varying concentrations of graphene (0.25–3.00 wt%) for direct contact membrane distillation (DCMD). The membranes were characterized by SEM, AFM contact angle, porosity, and Zeta potential. DCMD experiments were conducted with feed and permeate streams operating in countercurrent flow, along with dye and salt rejection tests and static adsorption experiments. Results indicated that the M1G membrane (0.25 wt% graphene) achieved the most balanced performance, exhibiting a high-water contact angle (117.18°) and the highest permeate flux (28.79 kg·m⁻2·h⁻1) when treating real textile effluent. This flux represented a significant improvement over the pristine PVDF membrane (M0). While higher graphene loadings led to surface densification and filler agglomeration, reducing flux in the M5G (3.00 wt%) sample, low-level functionalization optimized the vapor transport pathways and enhanced surface hydrophobicity. Furthermore, the M1G membrane demonstrated superior anti-fouling properties, with dye adsorption reduced to 0.61% compared to 1.69% for the M0 membrane, attributed to a more negative Zeta potential and reduced surface free energy. All modified membranes-maintained color and salt rejection rates near 100%. These findings demonstrate that precisely tailoring graphene concentration can significantly mitigate wetting and fouling challenges, making PVDF-graphene MMMs a robust and efficient alternative for the advanced treatment of complex industrial textile effluents and for promoting a circular economy.