Hybrid organic-inorganic functionalized polyethersulfone membrane for hyper-saline feed with humic acid in direct contact membrane distillation

Abstract

In this study, hybrid organic-inorganic functionalized polyethersulfone (PES) membrane was prepared for treating hyper-saline feed solutions containing humic acid (HA) foulant. The membrane modification was carried out by dip-coating with silica nanoparticles, followed by vacuum filtration coating with 1H,1H,2H,2H-perfluorodecyl triethoxysilane and polydimethylsiloxane. The membranes were characterized by field emission scanning electron microscope, atomic force microscope, Fourier transform infrared, and thermal gravimetric analyses. The evaluation of membranes with water contact angle, liquid entry pressure, direct contact membrane distillation (DCDM), and stability tests, proved the durable amphiphobic nature of the modified PES membrane (PDMS-FAS/SiNPs). The membrane performance was respectively better from that of commercial polypropylene (PP) and polyvinylidene fluoride (PVDF) membranes. In the DCMD of a feed solution of 1 M NaCl and 10 mg L-1 HA, the flux of the PDMS-FAS/SiNPs membrane remained consistent (17 LMH), with a permeate conductivity of 33.96 mu S cm(-1). The optimized modified membrane showed better performance in terms of permeate flux, salt rejection, and anti-fouling behavior in DCMD. These wonderful results of functionalized PDMS-FAS/SiNPs PES membrane are attributed to the step-wise simple, and inexpensive dip-coating followed by vacuum filtration coating using efficient hybrid organic-inorganic material combination.