Influence of Casting Method on Pervaporational Performanses of Polyheptylmethylsiloxane Membranes

A method of composite membrane obtaining effects on its transport properties. In the present work, for the first time, the influence of the method of applying a selective layer of polyheptylmethylsiloxane on the composite membrane pervaporation properties in the process of alcohol separation from water was studied. The comparison of two casting methods (kiss-coating and spin-coating) was conducted. Morphology of the obtained membranes and their separation properties during the pervaporation of the mixture of C2-C4 alcohols and water. It was shown that kiss-coating allows completely prevent leakage of the selective layer into the substrate pores. And, such a way, it allows to improve permeability of composite membrane (BuOH - 3.5 mol/(kPa·h·m2)). Besides, spin-coating method leads to higher selectivity (BuOH/H2O - 2.3). It is caused by blocking the swelling of that part of the selective layer that is locked in the pores of the substrate. Thus, the choice of the casting method can determine the compatibility of the composite membrane with a specific separation task.

Effect of Temperature and Branched Crosslinkers on Supported Graphene Oxide Pervaporation Membranes for Ethanol Dehydration

We describe the performance of graphene oxide (GO) membranes stabilized by crosslinkers and supported on polyethersulfone films in the dehydration of ethanol in a continuous cross-flow pervaporation set-up. We used two crosslinker species with branched structures (humic acid-like substances derived from urban waste and a synthetic hyperbranched polyol). The supported crosslinked GO films were prepared by rod coating on a polyethersulfone ultrafiltration membrane. Pervaporation experiments were carried out at temperatures of 40, 50, 60 and 70 °C. When the feed comprised pure water and ethanol, a much higher flux of water than ethanol was observed at all temperatures through GO films stabilized by the two crosslinkers (humic acid, GO-HAL, and the synthetic hyperbranched polyol, GO-HBPO), indicating the separation ability of these crosslinked membranes. For feed mixtures of water and ethanol, the GO-HAL and GO-HBPO membranes showed good separation performances by producing permeates with a significantly higher water content than the feed at all temperatures.

Techno-Economic Analysis (TEA) of Different Pretreatment and Product Separation Technologies for Cellulosic Butanol Production from Oil Palm Frond

Among the driving factors for the high production cost of cellulosic butanol lies the pretreatment and product separation sections, which often demand high amounts of energy, chemicals, and water. In this study, techno-economic analysis of several pretreatments and product separation technologies were conducted and compared. Among the pretreatment technologies evaluated, low-moisture anhydrous ammonia (LMAA) pretreatment has shown notable potential with a pretreatment cost of $0.16/L butanol. Other pretreatment technologies evaluated were autohydrolysis, soaking in aqueous ammonia (SAA), and soaking in sodium hydroxide solution (NaOH) with pretreatment costs of $1.98/L, $3.77/L, and $0.61/L, respectively. Evaluation of different product separation technologies for acetone-butanol-ethanol (ABE) fermentation process have shown that in situ stripping has the lowest separation cost, which was $0.21/L. Other product separation technologies tested were dual extraction, adsorption, and membrane pervaporation, with the separation costs of $0.38/L, $2.25/L, and $0.45/L, respectively. The evaluations have shown that production of cellulosic butanol using combined LMAA pretreatment and in situ stripping or with dual extraction recorded among the lowest butanol production cost. However, dual extraction model has a total solvent productivity of approximately 6% higher than those of in situ stripping model.