Physicochemical study of polyvinylidene fluoride-Cloisite15A (R) composite membranes for membrane distillation application

In this work, polyvinylidene fluoride-Cloisite15A (R) (PVDF-C15A) hollow fiber membranes were prepared, characterized and evaluated. The membranes were applied to treat a dye solution via a direct contact membrane distillation (DCMD) system. The concentration of the C15A incorporated into the PVDF membrane was varied (3, 5 and 10 wt%) and the corresponding effects were investigated in terms of structural properties and performances. The PVDF-C15A membranes were prepared using a dry-jet wet spinning method and characterized with respect to their morphology, porosity, wetting pressure, contact angle, surface roughness, mechanical strength and thermal stability. The presence of the C15A particles was confirmed by Fourier-transform infrared (FTIR), X-ray diffraction (XRD) and scanning electron microscopy with an energy dispersive X-ray spectroscopy (SEM-EDX) analysis. Highly porous membranes with large finger-like structures were shown by the SEM images. The characterization results indicated that the incorporation of C15A particles has shown a significant influence on the physicochemical properties of the membranes. The DCMD experiments revealed that the PVDF membrane incorporated with 3 wt% C15A (PVDF-3% C15A) exhibited the best MD performance in which complete dye rejection was able to be achieved with consistent permeate flux. The promising results obtained by the PVDF-3% C15A membrane are mainly attributed to its improved structural properties resulting from the good distribution of C15A particles in the membrane matrix. This study shows that the PVDF membranes incorporated with C15A particles have potential to further improve the performances of pristine PVDF membranes in DCMD of dyeing wastewater.