Novel bentonite modified PVDF membrane for desalination of synthetic-produced water by vacuum membrane distillation

Abstract

ABSTRACT Membrane distillation (MD) has emerged as a highly promising method for the treatment of intricate and heavily contaminated water sources, such as those containing oily wastewater. The present study endeavors to advance the field by designing and evaluating a novel nanocomposite membrane comprised polyvinylidene fluoride (PVDF) and Bentonite (BNT) for application in vacuum membrane distillation (VMD) processes targeted at treating oily wastewater. A series of five nanocomposite flat sheet membranes were meticulously fabricated, incorporating varying quantities of bentonite (ranging from 0 to 0.8 g). Systematic characterizations were meticulously undertaken to comprehensively elucidate the influence of BNT incorporation on the structural and functional attributes of the developed membranes. These encompassed an array of analytical techniques, including Fourier Transform Infrared Spectroscopy (FTIR), atomic Force Microscopy (AFM), X-Ray diffraction (XRD), field emission scanning electron microscopy (FESEM), contact angle measurements (CA), as well as assessments of membrane thickness, porosity, pore size, and pore size distribution. The findings distinctly showcased the successful integration of BNT within the PVDF matrix, which correspondingly led to discernable augmentations in membrane surface roughness, hydrophobicity, and porosity. Employing consistent operational conditions involving a feed temperature of 50°C, a vacuum pressure of 30 kPa, and a NaCl solution with a concentration of 14.75 g/L, VMD experiments were systematically conducted. The empirical outcomes revealed that the incorporation of BNT notably conferred substantial enhancements upon the nanocomposite membrane’s performance. The pinnacle achievement was evidenced in a flux rate of 34 L/m2.h and a remarkable NaCl rejection rate of 99.92%, a result achieved by the nanocomposite membrane incorporating the highest content of BNT additives.