RESUMEN
Designing hollow fiber (HF) membrane modules occupies one of the key positions in the development of efficient membrane processes for various purposes. In developing HF membrane modules, it is very important to have a uniform HF distribution and flow mixing in the shell side to significantly improve mass transfer and efficiency. This work suggests the application of different textile 3D HF structures (braided hoses and woven tape fabrics). The 3D structures consist of melt-spun, dense HFs based on poly(4-methyl-1-pentene) (PMP). Since the textile processing of HFs can damage the wall of the fiber or close the fiber bore, the membrane properties of the obtained structures are tested with a CO2/CH4 mixture in the temperature range of 0 to 40 °C. It is shown that HFs within the textile structure keep the same transport and separation characteristics compared to initial HFs. The mechanical properties of the PMP-based HFs allow their use in typical textile processes for the production of various membrane structures, even at a larger scale. PMP-based membranes can find application in separation processes, where other polymeric membranes are not stable. For example, they can be used for the separation of hydrocarbons or gas mixtures with volatile organic compounds.
RESUMEN
Zeolite-NaA membranes were synthesized from an extract of fused South African fly ash on a porous titanium support by a secondary growth method. The influence of the synthesis molar regime on the formation of zeolite NaA membrane layer was investigated. Two synthesis mixtures were generated by adding either aluminium hydroxide or sodium aluminate to the fused fly ash extract. The feedstock material and the synthesized membranes were characterized by X-diffraction (XRD), scanning electron microscopy (SEM) and X-ray fluorescence spectroscopy (XRF). It was found by XRD and SEM that the cubic crystals of a typical zeolite NaA with a dense intergrown layer was formed on the porous Ti support. The study shows that the source of Al used had an effect on the membrane integrity as sodium aluminate provided the appropriate amount of Na(+) to form a coherent membrane of zeolite NaA, whereas aluminium hydroxide did not. Morphological, the single hydrothermal stage seeded support formed an interlocked array of zeolite NaA particles with neighbouring crystals. Also, a robust, continuous and well-intergrown zeolite NaA membrane was formed with neighbouring crystals of zeolite fused to each other after the multiple stage synthesis. The synthesized membrane was permeable to He (6.0 × 10(6) L m(-2)h(-1) atm(-1)) and CO2 (5.6 × 10(6) L m(-2)h(-1) atm(-1)), which indicate that the layer of the membrane was firmly attached to the porous Ti support. Membrane selectivity was maintained showing membrane integrity with permselectivity of 1.1, showing that a waste feedstock, fly ash, could be utilized for preparing robust zeolite NaA membranes on Ti support.