A new technique for preparation of PDMS/ceramic nanocomposite membrane for gaseous hydrocarbons separation

Abstract

A novel composite membrane using polydimethylsiloxane (PDMS) as a top active layer and ceramic nanocomposite as the support layer was developed for the gaseous hydrocarbons separation. For the fabrication of hybrid membranes, nanocomposite technology applied for manufacturing ceramic supports with controllable microstructures. Also, a new method was used for coating a uniform and no penetrated polymeric layer. Top layer of ceramic support with nanocomposite microstructures was fabricated using 5 wt % a-Al 2 O 3 -SiO 2 bidispersed suspensions with optimum weight fraction of second phase (SiO 2 ) based on the fractional collision frequency theory. PDMS selective layer was coated on the outer surface of the porous ceramic nanocomposite support by dip-coating method. In this respect, the effect of several parameters such as pretreatment temperature, PDMS solution concentration, and number of coated polymeric layers on prepared layers morphology and hybrid membrane performance in the separation of condensable hydrocarbons (iso and n-butane) from hydrogen were investigated. The results showed that the membranes fabricated at 140 C as pretreatment temperature and three polymeric layers by 7, 15, and 15 wt % PDMS concentration, respectively, had a high selectivity (>25 at 2 bar)) in C 4 H 10 /H 2 separation.

Spray‐coatedPDMS/PVDFcomposite membrane for enhanced butanol recovery by pervaporation

“…The EDS elemental mapping of silicon in PDMS composite membranes was used to study the permeate of PDMS into the support layer. A small amount of permeate promotes the attachment of PDMS and the support layer, while too much intrusion into the support pores increases transport resistance and reduces flux 38,39 . The SEM cross‐sectional images and the change of Si concentrations through PDMS/PVDF(ultrafiltration) and PDMS/PVDF(microfiltration) composite membranes, respectively, are shown in Figure 2.…”

“…A small amount of permeate promotes the attachment of PDMS and the support layer, while too much intrusion into the support pores increases transport resistance and reduces flux. 38,39 The SEM cross-sectional images and the change of Si concentrations through PDMS/PVDF(ultrafiltration) and PDMS/PVDF(microfiltration) composite membranes, respectively, are shown in Figure 2. The high Si signals on the left side of the graphs corresponded to the high Si concentration in the PDMS layer.…”