Search

BACKGROUND Polybenzoxazine ( PBZ) membranes have received increasing attention for serving as a high performance membrane for pervaporation processes owing to their good mechanical properties, high chemical resistance, high thermal stability, and low synthesis cost. This study aims to develop PBZ membrane and NaA-PBZ mixed matrix membrane ( MMM) for purification of ethanol/water mixtures using a pervaporation process and to investigate the effects of preparation parameters on the membrane performance, including precursor concentrations, number of dippings, amount of NaA zeolite loading, temperature, and ethanol concentration. RESULTS It was found that PBZ membrane and NaA-PBZ MMM exhibited excellent stability in all feed ethanol concentrations tested, with a low degree of swelling. The highest separation factor of the pure PBZ membrane was more than 10 000 while the NaA-PBZ MMM was even higher, up to and, in some cases, higher than 100 000 with the highest permeation flux of 1071 g m−2 h−1 when using 25 wt% PBZ precursor with 15 wt% NaA zeolite loading. The permeation flux of MMM increased with increase in temperature or a decrease in the feed ethanol concentration. Swelling increased when the ethanol concentration was increased, revealing the hydrophobic behavior of NaA-PBZ MMM. CONCLUSION The membranes are capable of purifying ethanol over a wide feed ethanol concentration range with excellent performance and properties that promise great potential for use in bioethanol purifying applications. © 2015 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Effects of tetrahydrofuran (THF) concentration on the mixed methane hydrate formation, dissociation, and stability were investigated. The experiment was conducted at 286.2 K and 6 MPa in a quiescent reactor. The presence of THF below 2.5 mol% did not show the evidence of hydrate formation. However, the concentration above 2.5 mol% enhanced the methane formation rate and the methane consumption. Increasing the THF concentration decreased the induction time as the result of the decrease in the surface tension. Moreover, the methane uptake and formation rate increased with the THF concentration due to the higher degree of hydrate nucleation. The methane recovery after the dissociation experiment showed up to 96%. Furthermore, the hydrate stability increased, and the hydrate dissociation kinetics decreased with the increase in the THF concentration. The optimum THF concentration to enhance and improve the hydrate formation kinetics and stability is its stoichiometric concentration.