Synthesis Of PE-b-PEO Block Copolymer And Its Pervaporation Performance For The Separation Of N-Butanol/H₂O Mixtures

As an excellent organic solvent and key raw chemical material, butanol may also be used as a promising biofuel. Pervaporation could be coupled with ABE fermentation to improve the butanol productivity and process efficiency. Moreover, the development of the membrane materials with high performance is key to the industrial application of the fermentation—PV coupled process. In this work, the poly-(ethylene-b-ethylene oxide) block copolymers (PE-b-PEO) were synthesized by a new method based on the sequential anionic polymerization and hydrogenation under atmospheric pressure, which could be used as membrane materials for pervaporation separation of butanol/H2O mixtures.The poly (butadiene-b-ethylene oxide) block copolymers(PB-b-PEO) were synthesized by sequential anionic polymerization using n-BuLi as initiator and triisobutyl aluminium as addictive, then the obtained PB-b-PEO were hydrogenated by p-toluenesulfonyl hydrazide (TSH) under atmospheric pressure, which resulted in poly(ethylene-b-ethylene oxide)(PE-b-PEO) block copolymers. A series of PE-b-PEO block copolymers with narrow molecular weight distribution were synthesized using this method. The copolymers were characterized by gel permeation chromatography (GPC), proton nuclear magnetic resonance (’H-NMR) and Fourier Transform Infrared Spectrometer (FTIR). The results showed that PE-b-PEO block copolymers with tuneable molecular structures could be prepared using the method provided herein.The PE-b-PEO homogeneous membranes were prepared by melting method. The effects of the composition and molecular weight of copolymers on pervaporation performance for separation of n-butanol/H20mixtures were studied. It was found that the separation factor of n-Butanol/H2O decreased with the degree of polymerization (DP) of PE block.The mechanical stability of membrane was determined by the DP of PE block. The separation factor of n-Butanol/H20increased with the DP of PEO block. Furthermore, the effects of feed concentration, operating temperature on the pervaporation performance were investigated. It was demonstrated that with the increase of butanol concentration in the feed, the total permeation flux increased linearly, while the separation factor of n-Butanol/H2O decreased. Both the permeation flux and separation factor increased with operating temperature, and the temperature dependency of the permeation flux could be described by the Arrhenius equation.