عنوان مقاله [English]
Hypothesis: Despite the wide application of nanofiltration (NF) membranes in forward osmosis (FO) process, one of the most important challenges of this process is the internal concentration polarization (ICP) phenomenon. Different methods have been investigated to reduce the effect of this undesirable phenomenon and it is suggested that one of these methods is loading of hydrophilic nanoparticles in the membrane structure. In this study, SiO2/ZIF-8 nanoparticles were used to improve the structure and performance of polyethersulfone membranes (PES) in FO process.
Methods: At first, polyethersulfone membrane was synthesized by phase inversion method. In the next step, ZIF-8 and SiO2/ZIF-8 nanoparticles as filler were synthesized at room temperature. Thin film composite membranes were prepared by the interfacial polymerization (IP) of two reactive organic (TMC) and aqueous (MPD) monomers. Finally, the produced membranes and nanocomposite were characterized by contact angle, FTIR spectroscopy, X-ray diffractometry (XRD), field emission scanning electron microscopy (FESEM), and porosity measurements. Also, the performance of all membranes composed of at least two different components was investigated using reverse and forward osmosisi processes.
Finding: The outcomes demonstrated that the presence of a small amount of SiO2/ZIF-8 nanoparticle in the membrane led to an increase in the membrane hydrophilicity and porosity, and also improved the water flux and rejection of the FO. The water flux of TFN FO membrane was reported to increase remarkably from 15.23 to 25.13 L/m2.h when 10 mM NaCl and 2 M NaCl salt were utilized as feed solution (FS) and draw solution (DS), respectively. The improvement in FO water flux was ascribed to the lower S parameter of modified PES sublayer and the reduction of internal concentration polarization (ICP).