Taking advantage of large water-unstable Zn4O(BDC)3 nanoparticles for fabricating the PMM-based TFC FO membrane with improved water flux in desalination process

Developing the forward osmosis (FO) membranes to enhance their efficiency is of great importance as this technology is an important option to overcome water scarcity. In the present study, the water-unstable Zn4O(BDC)3 (where BDC = 1,4-benzodicarboxylate) nanoparticles of different sizes were embedded into the polyethersulfone (PES) matrix to form the porous-matrix membranes (PMMs) as the support layers in the forward osmosis FO thin-film composite (TFC) membranes. The main idea of this approach is to suppress the negative effect of the dilutive internal concentration polarization (DICP) in the FO mode by increasing the mean pore size and porosity of the support layer of the TFC FO membranes, leading to an enhanced FO water flux. According to the results, the water flux (Jw) increased from 26 L/m2.h in the pristine membrane (TFC-C) to 34 L/m2.h in the TFC-MOF-2 membrane fabricated with the large size Zn4O(BDC)3 nanoparticles (108 nm particle size and 2 wt. % loadings). Also, this membrane was used for the Caspian seawater desalination, and the water flux of 28.10 L/m2h (18.72 for the TFC-C) and the water flux reduction of 6 % (18.48 % for the TFC-C) during the long-term experiment were obtained.