Desalination via Innovative Membrane Process

Abstract

Desalinated seawater has been used for process or boiler water in industry. Thermal distillation and reverse osmosis are well known desalination technique and they are mostly used to desalinate brackish or seawater around the word. Recently innovative pervaporation process has been investigated by the researchers.

In this study pervaporation process has been investigated to desalinate the sea water with high efficiency. For this purpose pristine, and zeolite 3A which has 0.3 nm cage size (5, 10 wt. % of zeolite with respect to the dry polymer weight) filled sodium alginate (NaAlg) membranes have been prepared by the solution casting method. The salt retention and water flux values have been investigated to evaluate the performance of the system depending on the calculated data. Sodium alginate is a kind of polysaccharide which is found in brown seaweed. It exhibits high affinity to water molecules so it has been recently used in pervaporation. In this study, hydrophilic zeolite 3A was incorporated into the NaAlg in order to enhance the mechanical, chemical stability and the water flux of the membrane. Zeolite 3A is appropriate zeolite to allow the transition of water molecules (0.27 nm) and to prevent the transition of Na⁺ (0.36 nm) and Cl^- (0.38 nm) ions.  The experiments have been carried out at 20 °C, 30 °C and 40 °C to determine the effect of temperature. Also the optimum zeolite filling effect has been investigated.

As a result of this study it was seen that, with increasing the feed temperature flux values increased. Also the zeolite loading was increased the water flux. In both pristine and zeolite filled membrane, almost 100% salt retention was achieved.