Desalination of aqueous solutions by LTA and MFI zeolite membranes using pervaporation method

Abstract

-LTA and MFI zeolite membranes were hydrothermally grown on the surface of an α-alumina porous support. The synthesized membranes were used for removal of cationic and anionic species from aqueous solutions by the pervaporation method. The perfection of the membranes was improved by employing the multi-stage synthesis method. The membranes were characterized by XRD, SEM and IR methods. The membranes were initially evaluated by the pervaporation separation of water from aqueous 2-propanol mixtures. The separation factors obtained were 7081 and 105 for NaA and ZSM-5 membranes, respectively. The ability of membranes for desalination of some aqueous solutions containing I -, Cs + and Sr 2+ ions was examined in various conditions. These ionic species were chosen because of their importance in the nuclear sciences. Both membranes effectively removed (more than 99 wt%) I -, Cs + and Sr 2+ from their singlesalt solutions (0.001mol dm -3 ) over a temperature range of 298-338 K. The effects of parameters such as time and temperature on the separation factors and fluxes were investigated. This work shows that, due to their excellent chemical, thermal and mechanical stability, the zeolitic membranes are useful for desalination of aqueous solutions and treating saline wastewaters by pervaporation. Therefore, this method has the ability to desalinate harsh environment solutions involving strong solvent and radioactive components.

Organic-inorganic hybrid membranes in separation processes: a 10-year review

“…In the last three decades, significant improvements in the performance of polymeric membranes for ultrafiltration, nanofiltration, pervaporation, gas separation, and fuel cells have been made (Malekpour et al, 2011;Yi et al, 2010;Ferraz et al, 2007;Mehta and Zydney, 2005;Nyström et al, 1995;Pagliero et al, 1993;Vittadello et al, 2003;Thayumanasundaram et al, 2010), and our understanding of the relationships between the structure, permeability and selectivity of polymeric membranes has been greatly advanced (Geise et al, 2011;Dal-Cin et al, 2008;Cong et al 2007). Polymeric membrane materials such as polytrimethylsilyl propyne (PTMSP), poly(amide imide) (PAI), polyphosphazene (PPN), Poly(dimethylsiloxane) (PDMS), cross-linked polyethylene glycol (PEG) and polyoctylmethylsiloxane (POMS) have been continuously studied (Ozdemir et al, 2006).…”

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

“…In another study, the same group reported high NaCl rejection of ~97% and water flux of 3 kg m −2 h −1 in PV using a carbonized template silica membrane [109]. Malekpour et al [111] reported very high salt rejections up to 99% during desalination of radioactive solutions (i.e., 0.001 (M) of Cs + , Sr 2+ , and MoO 4 2− ) using NaA zeolite membranes. With the increase in PV time, the total flux was found to decrease because of the precipitation of salts into the non-zeolitic pores.…”

Fabrication of efficient pervaporation desalination membrane by reinforcement of poly(vinyl alcohol)–silica film on porous polysulfone hollow fiber

“…Different types of hydrophilic membrane materials, including organic, inorganic, and organic–inorganic hybrids, have been reported for pervaporation desalination. Among the inorganic materials, Zeolite A, natural clinoptilolite‐phosphate zeolite, hydroxysodalite, ZSM‐5 to MFI (Mobile‐5) having different Si/Al ratios, alumina and titania modified by 1 H ,1 H ,2 H ,2 H ‐perfluorodecyltriethoxysilane (FAS), and membranes based on silica and cobalt oxide particles in a silica matrix have been reported. Recently, a metal organic framework based on zeolitic imidazolate framework (ZIF) membranes supported on bioinspired polydopamine‐modified α‐Al 2 O 3 disks was also tested for pervaporation desalination .…”

“…The cost is increased by the requirement for a high sintering temperature in the final fabrication step of the ceramic membrane. The cost of conventional polymeric membranes is around $50–200/m, which is at least 10 times cheaper than that of ceramic membranes. Moreover, the manufacturing cost of the tubular ceramic membrane could be further increased by the inherent complexity of homogenous tubular mold preparation …”