Designing 3D Membrane Modules for Gas Separation Based on Hollow Fibers from Poly(4-methyl-1-pentene)

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.

Biodiesel production from catfish (Pangasius) fat via ultrasound- assisted method

This paper reports studies in ultrasound-assisted heterogeneous solid catalyzed (CaO) synthesis of biodiesel from catfish (Pangasius) fat. Ultrasonication provides a faster chemical reaction, and the rate enhancements, refereed by cavitation that causes the building- up of pressures and temperatures, as well as increased catalytic surface areas and improve mass transfer. This novel method offers significant advantages such as shorter reaction time and less energy consumption than the conventional method, efficient molar ratio of methanol to triglycerides and provides the mechanical energy for mixing. The required activation energy for initiating the transesterification reaction and so, it gives a higher yield by transesterification of oils into biodiesel. The optimized reaction conditions were as follows: methanol to oil molar ratio of 15:1; catalyst (B-CaO), 9 wt. %; reaction temperature, 65 ± 2 °C; reaction time, 1 h at a working frequency of 42 kHz and the power supply of 100W. Highest conversion of 96.4 wt. % was achieved.

Effects of Ultrasound on Fermentation of Glucose to Ethanol by Saccharomyces cerevisiae

Previous studies have shown that pretreatment of corn slurries using ultrasound improves starch release and ethanol yield during biofuel production. However, studies on its effects on the mass transfer of substrates and products during fermentation have shown that it can have both beneficial and inhibitory effects. In this study, the effects of ultrasound on mass transfer limitations during fermentation were examined. Calculation of the external and intraparticle observable moduli under a range of conditions indicate that no external or intraparticle mass transfer limitations should exist for the mass transfer of glucose, ethanol, or carbon dioxide. Fermentations of glucose to ethanol using Saccharomyces cerevisiae were conducted at different ultrasound intensities to examine its effects on glucose uptake, ethanol production, and yeast population and viability. Four treatments were compared: direct ultrasound at intensities of 23 and 32 W/L, indirect ultrasound (1.4 W/L), and no-ultrasound. Direct and indirect ultrasound had negative effects on yeast performance and viability, and reduced the rates of glucose uptake and ethanol production. These results indicate that ultrasound during fermentation, at the levels applied, is inhibitory and not expected to improve mass transfer limitations.

Allyl type monomers for hard surface coating protection

Based on the unsaturated derivatives of polyfluoroalkanols chemical products are used to protect solid and fibrous materials surface from the effects of water, oils and other pollutants. A method for obtaining allyl ethers of polyfluoroalkanols (polyfluoroalkoxypropenes) is based on the Williamson ether reaction. This method is a heterophase process. The use of solvents to improve mass transfer requires complementary measures to ensure industrial and environmental safety. It is more preferable to obtain the target ethers in water with PTC. A series of experiments using different chain length polyfluoroalkanols was studied by GLC. Kovats retention indexes of the target ethers were determined. It was found that in the case of lower homologues (CF3CH2OH, (CF3)2CHOH, HCF2CF2CH2OH), the addition of 5-15 vol.% 1,4-dioxane as a solubilizer provides a high yield of products. The application of PTC (tetrabutylammonium bromide) is indispensable for using polyfluoroalkanols with a longer carbon chain (C≥5). PTC invariably provides the almost complete conversion of polyfluoroalkanols. The decomposition process of TBAB becomes noticeable (GLC method) upon completion of the main reaction. Polyfluoroalkoxypropenes form azeotrope with water, which can be used in the work up process.

Ohmic heating/vacuum impregnation treatments on osmodehydrated apples enriched in polyphenols from concentrated pomegranate juice

The aim of this work was to study the combination of osmodehydration (OD), coupled with Ohmic Heating (OH) and Pulsed Vacuum (PV) and to introduce natural compounds from a cryoconcentrated pomegranate juice (47°Brix) at 30, 40 and 50 °C into apple matrix, during 180 min. PV was performed at 50 mbar for 5 min at the beginning of the process and OH generates an electric field of 6.6 V/cm. The results indicated that treatments reduced water content and increase polyphenol content of apples, evidencing that the osmotic treatment improve mass transfer, especially when they are applied together at higher temperatures. Keywords: Ohmic heating; pulsed vacuum; cryoconcentration; enriched; pomegranate.