Pervaporative enrichment of 2,3-butanediol from its mixture with 1-butanol using a polydimethylsiloxane and ZSM-5 mixed matrix membrane : effects of ethanol as a by-product

A ZSM-5 filled polydimethylsiloxane membrane with 44.4\u2009wt.% zeolite loading was used in the pervaporative removal of 1-butanol from its mixtures with 1-butanol. A small quantity of ethanol was added to the feed as a by-product to test the response of the membrane. It was found that the permeation behaviour of other feed components was changed and membrane selectivity decreased. This change was attributed to the frequently-observed inter-component coupled transport in multi-component feed systems. The impact of ethanol on recovery of 2,3-butanediol was evaluated using a simulated continuous operation, which enriched 2,3-butanediol to 99.5\u2009wt.% from a feed containing 5\u2009wt.% 2,3-butanediol and less than 1.0\u2009wt.% ethanol. It was observed that membrane selectivity improves as ethanol concentration decreases in the stream due to its preferential removal. The final recovery of 2,3-butanediol was not significantly reduced as the concentration of ethanol was below 1.0\u2009wt.%.Peer reviewed: YesNRC publication: Ye

Separation of 1-butanol/2,3 butanediol using ZSM-5 zeolite-filled polydimethylsiloxane membranes

Mixed matrix membranes were prepared by incorporating ZSM-5 zeolite particles into polydimethylsiloxane. A uniform dispersion of the zeolite in the membrane was obtained. The membranes were characterized with scanning electron microscopy, and the effects of zeolite loading on membrane performance were evaluated. It was found that 80 wt.% ZSM-5 loading was optimal for selectivity. Further increase in the zeolite loading either improved the selectivity slightly or even lowered the membrane selectivity while the membrane permeability was consistently reduced. The improved separating performance of the filled membranes was attributed to the filler\u2013polymer interactions, and the mass transfer contribution of surface flow through the zeolite pores. The advantage of the improved membrane performance was demonstrated in a simulated continuous operation enriching 2,3-butanediol in a mixture with 1-butanol from 5 to 99.5 wt.% as a retentate using both the filled and un-filled PDMS membranes. Results showed that the filled PDMS membrane improved the recovery of 2,3-butanediol significantly while achieving the same product purity.NRC publication: Ye

Recovery of 2,3-butanediol from water by a solvent extraction and pervaporation separation scheme

An integrated separation scheme based on solvent extraction and pervaporation was proposed to recover 2,3-buthanediol from a synthetic fermentation broth. The selected extracting solvent 1-butanol was found to be more suitable than others. Polydimethylsiloxane membrane was employed to further enrich the 2,3-butanediol in the organic phase consisting of 2,3-butanediol, 1-butanol and water. Of the three species, water was found to be the most permeable in the membrane followed by 1-butanol, implying that concentration and purification of 2,3-butanediol as membrane retentate could be achieved by using the polydimethylsiloxane membrane alone. Two membrane batch operations, i.e., dehydration, and removal of 1-butanol using chitosan and polydimethylsiloxane composite membranes, respectively, were conducted to demonstrate the capability of the selected membranes for producing 2,3-butanediol with purities higher than 98 wt.%. And numerical simulation showed the viability of the membrane in continuous operation for the recovery of 2,3-buatendiol.On a propos\ue9 un processus int\ue9gr\ue9 bas\ue9 sur une extraction au solvant et une pervaporation pour la r\ue9cup\ue9ration du butane-2,3-diol dans un jus de fermentation synth\ue9tique. On a trouv\ue9 que le solvant d\u2019extraction retenu, le butan-1-ol, convenait mieux que d\u2019autres. On a utilis\ue9 une membrane en polydim\ue9thylsiloxane pour enrichir, en butane-2,3-diol, la phase organique constitu\ue9e de butane-2,3-diol, de butan-1-ol et d\u2019eau. Pour ces trois esp\ue8ces, on a trouv\ue9 que la perm\ue9abilit\ue9 de la membrane \ue9tait plus importante pour l\u2019eau, suivie de celle du butan-1-ol. Il serait donc possible de n\u2019utiliser qu\u2019une membrane en polydim\ue9thylsiloxane pour concentrer et purifier le butane-2,3-diol. On a r\ue9alis\ue9 une exploitation en lots avec deux membranes, c.-\ue0-d., utilisation de membranes en chitosane et en polydim\ue9thylsiloxane pour respectivement d\ue9shydrater et \ue9liminer le butan-1-ol, pour d\ue9montrer la capacit\ue9 des membranes retenues \ue0 produire du butane-2,3-diol ayant une puret\ue9 sup\ue9rieure \ue0 98 % en poids. Une simulation num\ue9rique a permis de d\ue9montrer la viabilit\ue9 de la membrane en fonctionnement continu pour la r\ue9cup\ue9ration du butane-2,3-diol.Peer reviewed: YesNRC publication: Ye

Process Energy Efficiency in Pervaporative and Vacuum Membrane Distillation Separation of 2,3-Butanediol

This work focused on the energy aspects of the pervaporative separation of 1-butanol/2,3-butanediol. A numeric model was developed to simulate the mass and energy balance of the pervaporation process. It was found that the distribution of evaporation heat requirement over the membrane area is asymmetric, and more than 85% of the heat was consumed in the 60% of the membrane area. It was also revealed that recycling the permeate having higher than 5% w/w 2,3-butanediol can improve the recovery of 2,3-butanediol, and thus enhance the process energy ef\ufb01ciency. Two recycling strategies (the single or multiple point admission of permeate to the retentate \ufb02ow) were explored. The speci\ufb01c energy requirement (the heat required by generating 1 kg 99.5% w/w 2,3-butanediol as product) was proposed to evaluate the process energy ef\ufb01ciency of both the pervaporation and vacuum membrane distillation, and it was shown that pervaporation can bring about nearly four times energy savings over the vacuum membrane distillation.Peer reviewed: YesNRC publication: Ye

Simulation of membrane-based CO2 capture in a coal-fired power plant

A two-stage membrane process is designed for CO2 capture from coal-fired power plants. Vacuum operation on the permeate side of the membrane is the preferred option to reduce the power demand for compressing the huge feed volume. The energy recovered from the CO2-depleted emission stream and the energy consumed for post-capture CO2 liquefaction are considered in this simulation study. A numerical modeling of the membrane process and a brief description on assessing both the capital and operating costs of the process are provided. It is found that the membrane area requirement is dominated by recovery of the lower concentrations of CO2 in the tail portion of the flue gas stream. Process optimizations allowing the minimal CO2 capture cost or minimal power demand indicate that current membrane technology is promising for flue gas CO2 capture, assuming a permeance of 1000 GPU and CO2/N2 selectivity of 30. The potential of membrane technology for CO2 capture was also explored by using membranes with a CO2/N2 selectivity of 50 and 200.Peer reviewed: YesNRC publication: Ye

Design and economics of a hybrid membrane\u2013temperature swing adsorption process for upgrading biogas

Processing biogas from wastewater digesters allows recovery of valuable methane and reduction in green house gas emissions. A two-stage membrane process, coupled with a temperature-swing-adsorption (TSA) as pre-treatment, was designed to generate pipeline quality methane. To improve methane recovery and process energy efficiency, the non-product streams of the membrane process were recycled and the permeate of the first membrane stage was maintained at a given pressure as the driving force for second membrane stage. The membrane process design was optimized by minimizing the objective function; the overall processing cost. It was found the membrane approach excels the PSA for producing pipeline quality methane (97% purity) in terms of methane recovery, processing cost and lower emissions. A techno-economic analysis showed that the payback time for an operation processing 200 Nm(3)/h of biogas was 6.8 months.Peer reviewed: YesNRC publication: Ye

Algae-dewatering using rotary drum vacuum filters: Process modeling, simulation and techno-economics

Clean and energy-efficient rotary drum vacuum filtration was selected to conduct algae-dewatering. The dynamic formation of an algal cake-layer on the filter surface was modeled by correlating the cake-layer permeability to the physical parameters of algae and cake-layer. The compressibility of algal cake-layer was taken into consideration in the modeling, and its effect on the algae-dewatering is discussed.The dewatering process was simulated to determine the process energy demand. Process economics were assessed considering the dewatering cost, which includes capital investment and energy cost and also labor, installation, maintenance and infrastructure. Optimal operating conditions and minimum dewatering cost were achieved by process optimization, and two cost-sensitive zones in operating the filtration were identified. The techno-economics showed that the dewatering cost can be further reduced by scaling up the process.Peer reviewed: YesNRC publication: Ye