Abstract
Knowing that the world is facing a shortage of fresh water, desalination, in its different forms including reverse osmosis, represents a practical approach to produce potable water from a saline source. In this report, two kinds of Metal-Organic Frameworks (MOFs) nanoparticles (NPs), UiO-66 (~100 nm) and MIL-125 (~100 nm), were embedded separately into thin-film composite membranes in different weight ratios, 0%, 0.05%, 0.1%, 0.15%, 0.2%, and 0.3%. The membranes were synthesized by the interfacial polymerization (IP) of m-phenylenediamine (MPD) in aqueous solution and trimesoyl chloride (TMC) in an organic phase. The as-prepared membranes were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), contact angle measurement, attenuated total reflection Fourier transform infrared (ATR FT-IR) spectroscopy, and salt rejection and water flux assessments. Results showed that both UiO-66 and MIL-125 could improve the membranes’ performance and the impacts depended on the NPs loading. At the optimum NPs loadings, 0.15% for UiO-66 and 0.3% for MIL-125, the water flux increased from 62.5 L/m2 h to 74.9 and 85.0 L/m2 h, respectively. NaCl rejection was not significantly affected (UiO-66) or slightly improved (MIL-125) by embedding these NPs, always at >98.5% as tested at 2000 ppm salt concentration and 300 psi transmembrane pressure. The results from this study demonstrate that it is promising to apply MOFs NPs to enhance the TFC membrane performance for desalination.
Highlights
Reverse osmosis (RO) is the most employed method of desalination to convert saline or brackish water source to freshwater
MIL-125’s zeta potential was lower than what was previously reported, around +2 mV at pH of 5.5 [67,68]. This could be due to the use of different titanium raw materials; titanium isopropoxide was used in this research instead of titanium butoxide used in previous studies
Incorporation of UiO-66 and MIL-125 Metal-Organic Frameworks (MOFs) NPs in reverse osmosis membranes is reported in this study
Summary
Reverse osmosis (RO) is the most employed method of desalination to convert saline or brackish water source to freshwater. The process uses a membrane as a selective barrier through which water molecules, but not the salts or organics, pass under pressure [1]. Desalination by various approaches, especially RO, represents a solution to address the water shortage problem that has become increasingly serious in the recent decades [2]. Development of RO processes and membranes has gone through many stages and forms since the first applicable membrane synthesis in the early. The TFC membrane has a polyamide dense layer with a thickness of a few hundred nanometers supported by an ultrafiltration membrane.
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