Desalination of simulated seawater by purge-air pervaporation using an innovative fabricated membrane

Abstract

An innovative polymeric membrane has been invented, which presents a breakthrough in the field of desalination membranes. It can desalinate simulated seawater of exceptionally high concentration to produce a high flux of potable water with over 99.7% salt rejection (%SR) in a once-through purge-air pervaporation (PV) process. A set-up was constructed for conducting the desalination experiments and the effect of initial salt solution concentration (Ci) and pervaporation temperature (Tpv) on the water flux (J), %SR, separation factor, and pervaporation separation index were determined. The membrane was prepared by the phase-inversion technique, of a specially formulated casting solution consisting of five ingredients, after which the membrane was subjected to a post-treatment by which certain properties were conferred. The results confirmed that the salinity of the pervaporate was independent of Ci (all %SR above 99.7). The best result was at Tpv=70 °C, where J varied from 5.97 to 3.45 l/m2 h for Ci=40-140 g NaCl/l, respectively. The membrane morphology was confirmed to be asymmetric. The contact angle was immeasurable, indicating the membrane to be super-hydrophilic. Activation energies computed using Arrhenius law were, under all conditions investigated, less than 20 kJ/mol K.

Preparation and characterization of PVA/GA/Laponite membranes to enhance pervaporation desalination performance

“…Hydrophilic dense polymeric membranes with high solubility of water are considered the most ideal for the pervaporation desalination process such as cellulose [15], polyether amide [8], poly(ether-blockamide) (PEBA) [16], and poly(vinyl alcohol) [9,17,18]. Despite these membranes have achieved high ion rejection, the reported water flux was commonly low and still needs to be improved for PV desalination.…”

Fabrication, Properties, Performances, and Separation Application of Polymeric Pervaporation Membranes: A Review

“…The membrane can effectively intercept borate, selenate and sodium chloride, and the recovered polluted water and low concentration saltwater, so it can be used in agricultural production [ 39 ]. The desalination capabilities of a hydrated cellulose membrane and a bacterial cellulose membrane prepared from plant cellulose (wood or cotton) were discussed by Naim et al [ 105 ]. Strong hydrophilic CA membrane was prepared by the basic phase transformation theory, although the membrane has asymmetric morphology, it has high desalination rate and large flux.…”

Structures, Properties, and Performances—Relationships of Polymeric Membranes for Pervaporative Desalination

“…All of these membranes have demonstrated ~100% salt rejection at 40 °C at the feed concentration of 40 g L −1 . Thereafter, Naim et al [132] obtained the maximum flux of 5.97 kg m −2 h −1 for the pervaporative desalination of 40 g L −1 NaCl solution at 70 °C through a super-hydrophilic CA membrane synthesized via simple phase inversion method.…”

“…Accordingly, improved hydrophilic character of super-hydrophilic cellulosic membrane was understood from the appearance of three O–H specific str. peaks for each anhydro-glucose unit, coupled with physically adsorbed water-specific peaks within 1640–1630 cm −1 [132].…”