نمك¬زدايي از محلول¬ها بوسيله غشاهاي در هم نفوذ يافته بر پايه پلي وينيل الكل و نانوكامپوزيت¬هاي آنها به روش تراوش تبخيري و اسمز معكوس

Water is an abundant natural resource on earth that covers three quarters of the earthʹs surface, but only three percent of it is accessible. Desalination by reverse osmosis and pervaporation can be the key to solving this problem. Among the membranes that are used in desalination, interpenetrating polymer network (IPN) membranes are a suitable option due to their good mechanical properties. So, interpenetrating polymer network (IPN) membrane and its modified form with NaA zeolite were prepared using polyvinyl alcohol (PVA)/polyacrylic acid (PAA) and were used in desalination of saline solutions by pervaporation and reverse osmosis. The prepared membranes were characterized using SEM, ATR, tensile and swelling test. The effective parameters in the membrane preparation were investigated and optimized through experimental design. Then, Salt rejection and solution flux were selected as the criteria for the membrane performances. The pervaporation results showed that the flux increases with the feed temperature going up and the membrane thickness decrease. However, better rejection was achieved at less feed temperature and more membrane thickness. At the optimized conditions, flux 7.1 kg/h.m2 and rejection 99% were obtained by net IPN membrane while, these parameters were changed to 11.2 kg/h.m2 and up to 95% by IPN/NaA membrane. Reverse osmosis experiments revealed that as the pressure on the membrane increases, the amount of flux goes up, while it requires less pressure and more cross linked membrane for having higher rejection (Flux 16.2 kg/h.m2 and rejection 90%). According to the obtained results, it was found that this composite membrane has a high ability in desalination with appropriate rejection and Fluxes. In second work, Composite membranes consisting of PVA/PAA as interpenetrating polymer networks (IPN), along with various MOFs (MIL-101-Cr, Cu-BTC, UiO-66-NH2) or graphene oxide (GO), were synthesized using a sequential method. These membranes were designed for use in the pervaporation desalination of NaCl and MgCl2 salts. The membranes were characterized using swelling, contact angle, ATR, tensile, and SEM tests, and the optimal preparation parameters were determined using an experiment design method. Subsequently, the optimal membranes were employed in the pervaporation desalination process, with salt rejection and fluxes serving as the pervaporation responses. The results showed that as the temperature of the feed increased, the water flux also increased. However, as the feed solution temperature and concentration increased, the salt rejection decreased. Under optimal conditions, the IPN/MIL-101-Cr membrane provided 15.19 and 14.59 kg/m2·h flux and 99.24% and 99.37% rejection for sodium and magnesium ions, respectively, while the GO/IPN membrane provided 13.65 and 12.98 kg/m2·h flux and 98.97% and 99.10% rejection for sodium and magnesium ions, respectively. These composite membranes also exhibited excellent performance in salt mixtures. Based on the experimental design results, preliminary eva‎luation tests, and comparison with other membranes, it can be concluded that the IPN/MIL-101-Cr composite membrane is highly effective for pervaporation desalination and has potential for industrial-scale applications.

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