Enhanced dye wastewater treatment via PVDF membrane distillation: Influence of dye classes on performance and fouling

Abstract

This study examines the application of polyvinylidene fluoride (PVDF) membrane distillation for the 12-hour treatment of dye wastewater, investigating the impact of various dye classes on membrane performance and fouling behaviour. Focusing on anionic dyes (Acid Red 27, Congo Red, Direct Red 80, Reactive Red 120), cationic dye (Basic Red 5), and non-ionic dye (Disperse Red 13), exceptional color rejection rates of over 99.5% were achieved. Acid Red and Direct Red displayed the highest permeate fluxes, achieving 20 liters per square meter per hour (LMH), while Disperse Red, due to its non-ionic properties, yielded a lower flux of 12 LMH. Field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDX), and Fourier-transform infrared spectroscopy (FTIR) analyses revealed key dye-membrane interactions, indicating that Congo Red showed the least fouling (13% flux decline). In comparison, Basic Red and Disperse Red produced the highest fouling index at 33.3%. Hermia's modelling confirmed compatibility with cake filtration and intermediate pore-blocking models, achieving an R² of 0.97. The PVDF membrane's durability across various dye classes emphasizes its potential for temperature-driven, sustainable wastewater treatment. These results highlight the significance of dye chemistry in optimizing membrane distillation processes for industrial wastewater management.