Acetone-butanol-ethanol Fermentation Broth Research Articles

1-Butanol Separation from Aqueous Acetone-Butanol-Ethanol (ABE) Solutions by Freeze Concentration

The suspension freeze crystallization of aqueous 1-butanol solutions, synthetic acetone-butanol-ethanol (ABE) solutions, and ABE fermentation broth was studied as a novel concentration method that requires less energy than evaporation for water removal. The equimolar aqueous ABE solutions in a total molality range of 0–5.05 mol/kg(water) were proven to be ideal solutions based on the freezing point depression obtained. An aqueous solution of 8 wt % 1-butanol and three different types of aqueous ABE solutions (3:8:1:88 ABEW, 6:16:2:76 ABEW, and 10:17:2:71 ABEW (wt %)) were concentrated for 80 min by suspension freeze crystallization in a subcooling range from 0.24 to 1.15 °C. Freeze crystallization enabled 1-butanol separation from the generated mother liquor, which split into two liquid phases after ice separation, i.e., a water-enriched phase and a 1-butanol-enriched phase. Ice yield values were higher for higher subcooling degrees and higher initial water content in the feed solutions. 1-Butanol yields separated from the mother liquors were 9.85%, 59.46%, and 22.46% for 3:8:1:88 ABEW, 6:16:2:76 ABEW, and 10:17:2:71 ABEW, respectively, whereas two-stage freeze crystallization of the fermentation broths resulted in water removal with a maximum relative percentage of 29.5%.

Separation of biobutanol from ABE fermentation broth using lignin as adsorbent: A totally sustainable approach with effective utilization of lignocellulose

Adsorption is considered to be a promising butanol recovery method for solving the issue of inhibition in the ABE (acetone-butanol-ethanol) fermentation. As a byproduct in the second generation biobutanol industry, lignin was found to be a good adsorbent for the butanol enrichment. It is conducive to the full utilization of renewable lignocellulose biomass resource. Kinetic and equilibrium experiments indicated that lignin had a satisfactory adsorption rate and capacity that are comparable to those of many synthetic materials. Multicomponent adsorption experiments revealed that lignin had higher adsorption selectivity toward butanol than that of ethanol and acetone. The adsorption capacity of lignin for butanol first increased and then gradually decreased with increasing temperature. And maximum adsorption capacity reached 304.66 mg g−1 at 313 K. The inflection point of temperature is close to the ABE fermentation temperature of 310 K. The condensed butanol by desorption was 145 g L−1, with a satisfying regeneration performance. 1H NMR and FT-IR spectra indicated that the aromatic units of lignin formed π-systems with A/B/E. The π-system is particularly significant for butanol due to its longer hydrocarbon chain. These results could contribute to the emerging lignin-based materials for butanol separation.

Pervaporation Performance of Polydimethylsiloxane-Polyvinylidene Fluoride Composite Membrane for Butanol Recovery from Model Solutions and Acetone-Butanol-Ethanol Fermentation Broth

Pervaporation has been identified as the most promising separation technology for butanol recovery in acetone-butanol-ethanol (ABE) fermentation, to overcome two main obstacles, low yield and high separation cost in the industrial-scale butanol production. In this work, we investigated the pervaporation performance of a thin flat polydimethylsiloxane (PDMS)-polyvinylidene fluoride (PVDF) composite membrane for butanol recovery from model solutions and ABE fermentation broth. The PDMS-PVDF composite membrane exhibited a high total flux of 1330 g m–2 h–1, and relatively higher separation factors of 21.2, 17.2, and 4.5 for acetone, butanol, and ethanol, respectively, with ABE-water solution. Compared to ABE-water solution, the total flux decreased by 3.25% and separation factors increased by 1.40%, 3.21%, and 3.92% for acetone, butanol, and ethanol in ABE fermentation broth, indicating that the negative effect of impermeable components present in the ABE fermentation broth was negligible. The excellent pervaporation performance and long-term operational stability of PDMS-PVDF composite membrane can enhance the efficacy of butanol recovery, thus it has potential to be used as a competitive pervaporation membrane in ABE fermentation process.

Effect of core-shell structuring of chabazite zeolite with a siliceous zeolite thin layer on the separation of acetone-butanol-ethanol vapor in humid vapor conditions

Due to its shape selective properties, the narrow pore chabazite zeolite is an interesting material for the separation and purification of 1-butanol from ABE (acetone-butanol-ethanol) fermentation broth, as it selectively traps ethanol from the mixture of acetone, ethanol and butanol. In order to improve the separation performance of chabazite zeolite in humid conditions, we synthesized a core-shell structured chabazite type zeolite, with a chabazite aluminosilicate core coated with a pure silica chabazite layer. This material was evaluated in the vapor phase separation of 1-butanol using a model ABE vapor mixture. Unexpectedly, a broader breakthrough profile of ethanol was obtained on the coated chabazite, resulting in a lower 1-butanol recovery. It was found that the adsorption rate of 1-butanol was decreased by the pure silica chabazite coating. In breakthrough experiments, the coated chabazite showed an even more pronounced exclusion of 1-butanol as compared to the parent material, resulting in a larger separation factor of ethanol over 1-butanol. The pure silica chabazite coating layer acts as a kind of diffusion barrier against 1-butanol rather than ethanol, enhancing the molecular sieving effect.

Energy-Efficient Design of Downstream Separation To Produce n-Butanol by Several Heat-Integrated Technologies

Biobutanol is a widely used biofuel, and it is traditionally produced mainly via the fermentation process of acetone–butanol–ethanol (ABE). However, separation of the ABE fermentation broth featuring a low concentration of n-butanol in the presence of butyric acid and acetic acid consumes considerable energy. For the sake of reducing the capital cost as well as the energy consumption greatly, a novel DWC-SHR process was proposed to achieve further energy saving through the combination of dividing wall column technology and the self-heat recuperation technology. Moreover, the heat exchanger network (HEN) can be applied to design the HEN of the DWC-SHR process. The DWC-SHR process can be compared with the base process as well as the heat-integrated processes (HI-A process and HI-B process) from the point of the energetic, economic, as well as environmental impact. The results illustrated that the DWC-SHR process can achieve 71.13%, 57.87%, and 47.79% savings of energy consumption compared to that of the bas...

Bio-butanol separation by adsorption on various materials: Assessment of isotherms and effects of other ABE-fermentation compounds

Abstract In the general effort to produce chemicals and fuels from renewable resources there is new interest in the biotechnological route to produce butanol. Acetone-Butanol-Ethanol (ABE) fermentation leads to low product yield because butanol is toxic to microorganisms. Selecting an efficient technology to recover butanol from low concentration butanol (about 2%) solutions is key to a successful implementation of this butanol production process on an industrial scale. Adsorption has been suggested as a potential technology for butanol recovery. This paper reports a systematic investigation of the adsorption of the metabolites that are typically present in the ABE fermentation broth: acetone, butanol, ethanol, acetic acid, butyric acid, yeast extract. The effect of glucose as a carbon source for the ABE fermentation was also investigated. Three adsorbents were characterized: Amberlite XAD-4, Amberlite XAD-7 and Zeolite Y. Batch tests under a wide interval of operating conditions were carried out for the assessment of the adsorption capacities of the three adsorbents. The selectivity of the three adsorbent materials towards the main components of ABE broths was also investigated. These tests were carried out using both dilute model solutions and real fermentation broths. The tests show that Amberlite XAD-7 has the highest affinity for butanol adsorption. The co-presence of all the metabolites in the solution - synthetic broth and real broth - changes the distribution in the adsorbed phase remarkably. The distribution of the concentration of the adsorbed components can be affected by pH. The presence of glucose does not affect butanol adsorption. Amberlite XAD-7 has a great potential as an adsorbent in ABE fermentation coupled with in situ recovery product removal techniques.

TECHNO-ECONOMIC ANALYSIS OF A BUTANOL RECOVERY PROCESS BASED ON GAS STRIPPING TECHNIQUE

Acetone-Butanol-Ethanol (ABE) industrial production by fermentation is strongly affected by the low concentration of solvent (<25 g/L) that affects the cost of the recovery process. To decrease the overall cost of the butanol production, alternative routes for the recovery have proposed in literature. This paper presents a techno-economic analysis of an innovative butanol recovery process from ABE fermentation broth based on gas stripping technique. The comparison with a recovery process based on conventional distillation is also presented. The investigated recovery line included gas stripping, absorption of butanol in a selected solvent, and distillation to separate the butanol from the selected liquid. The proposed and the conventional processes were modelled by means of the commercial software Aspen Plus to assess energy and material balances. The estimation of the investment cost was carried out by using Aspen Icarus and approximated methodologies typical of the process engineering. Gas stripping flow rate, solvent flow rate, and feed preheating temperature were explored as design variables. The effect of the butanol concentration in the typical fermentation broth was also presented and discussed. From the economic point of view, the proposed process was the most convenient to recover butanol from fermentation broth. The incidence of the recovered section on the assessed butanol production cost by fermentation ranged between 0.33 and 0.92 $/kg, when butanol concentration in the fermentation broth changed in the interval 5 - 18 g/L.

Separation of a Biofuel: Recovery of Biobutanol by Salting‐Out and Distillation

AbstractThe second generation biofuel butanol can be produced by acetone‐butanol‐ethanol (ABE) fermentation, but the separation from the broth is still challenging. Therefore, dipotassium hydrogen phosphate was investigated as salting‐out agent. The ABE fermentation broth was enriched by a prefractionator after being preheated. The enriched ABE solution was salted out by K2HPO4 solutions at different temperatures. The water in the supplemented ABE solution was largely removed by the salting‐out method. The energy requirements for the prefractionator and the butanol column were significantly reduced. The total energy demand for the recovery of acetone, butanol, and ethanol by salting‐out and subsequent distillation was optimized. With the salting‐out process, the entire salting‐out and distillation method turned out to be more energy‐saving than the conventional one.

Adsorption of water and butanol in silicalite-1 film studied with in situ attenuated total reflectance-Fourier transform infrared spectroscopy.

Biobutanol produced by, e.g., acetone-butanol-ethanol (ABE) fermentation is a promising alternative to petroleum-based chemicals as, e.g., solvent and fuel. Recovery of butanol from dilute fermentation broths by hydrophobic membranes and adsorbents has been identified as a promising route. In this work, the adsorption of water and butanol vapor in a silicalite-1 film was studied using in situ attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy to better understand the adsorption properties of silicalite-1 membranes and adsorbents. Single-component adsorption isotherms were determined in the temperature range of 35-120 °C, and the Langmuir model was successfully fitted to the experimental data. The adsorption of butanol is very favorable compared to that of water. When the silicalite-1 film was exposed to a butanol/water vapor mixture with 15 mol % butanol (which is the vapor composition of an aqueous solution containing 2 wt % butanol, a typical concentration in an ABE fermentation broth, i.e., the composition of the gas obtained from gas stripping of an ABE broth) at 35 °C, the adsorption selectivity toward butanol was as high as 107. These results confirm that silicalite-1 quite selectively adsorbs hydrocarbons from vapor mixtures. To the best of our knowledge, this is the first comprehensive study on the adsorption of water and butanol in silicalite-1 from vapor phase.

Acetone-butanol-ethanol competitive sorption simulation from single, binary, and ternary systems in a fixed-bed of KA-I resin.

Separation of butanol based on sorption methodology from acetone-butanol-ethanol (ABE) fermentation broth has advantages in terms of biocompatibility and stability, as well as economy, and therefore gains much attention. In this work a chromatographic column model based on the solid film linear driving force approach and the competitive Langmuir isotherm equations was used to predict the competitive sorption behaviors of ABE single, binary, and ternary mixture. It was observed that the outlet concentration of weaker retained components exceeded the inlet concentration, which is an evidence of competitive adsorption. Butanol, the strongest retained component, could replace ethanol almost completely and also most of acetone. In the end of this work, the proposed model was validated by comparison of the experimental and predicted ABE ternary breakthrough curves using the real ABE fermentation broth as a feed solution.

A carbon nanotube filled polydimethylsiloxane hybrid membrane for enhanced butanol recovery.

The carbon nanotubes (CNTs) filled polydimethylsiloxane (PDMS) hybrid membrane was fabricated to evaluate its potential for butanol recovery from acetone-butanol-ethanol (ABE) fermentation broth. Compared with the homogeneous PDMS membrane, the CNTs filled into the PDMS membrane were beneficial for the improvement of butanol recovery in butanol flux and separation factor. The CNTs acting as sorption-active sites with super hydrophobicity could give an alternative route for mass transport through the inner tubes or along the smooth surface. The maximum total flux and butanol separation factor reached up to 244.3 g/m2·h and 32.9, respectively, when the PDMS membrane filled with 10 wt% CNTs was used to separate butanol from the butanol/water solution at 80°C. In addition, the butanol flux and separation factor increased dramatically as temperature increased from 30°C to 80°C in feed solution since the higher temperature produced more free volumes in polymer chains to facilitate butanol permeation. A similar increase was also observed when butanol titer in solution increased from 10 g/L to 25 g/L. Overall, the CNTs/PDMS hybrid membrane with higher butanol flux and selectivity should have good potential for pervaporation separation of butanol from ABE fermentation broth.

Solvent screening methodology for in situ ABE extractive fermentation

Solvent screening for in situ liquid extraction of products from acetone-butanol-ethanol (ABE) fermentation was carried out, taking into account biological parameters (biocompatibility, bioavailability, and product yield) and extraction performance (partition coefficient and selectivity) determined in real fermentation broth. On the basis of different solvent characteristics obtained from literature, 16 compounds from different chemical families were selected and experimentally evaluated for their extraction capabilities in a real ABE fermentation broth system. From these compounds, nine potential solvents were also tested for their biocompatibility towards Clostridium acetobutylicum. Moreover, bioavailability and differences in substrate consumption and total n-butanol production with respect to solvent-free fermentations were quantified for each biocompatible solvent. Product yield was enhanced in the presence of organic solvents having higher affinity for butanol and butyric acid. Applying this methodology, it was found that the Guerbet alcohol 2-butyl-1-octanol presented the best extracting characteristics (the highest partition coefficient (6.76) and the third highest selectivity (644)), the highest butanol yield (27.4%), and maintained biocompatibility with C. acetobutylicum.

Hydrophobic-ZIF-71 filled PEBA mixed matrix membranes for recovery of biobutanol via pervaporation

As an alternative energy source to fossil fuels, biobutanol has received increasing attention. In this work, new mixed matrix membranes (MMMs) incorporating zeolitic imidazolate frameworks (ZIF-71) particles into polyether-block-amide (PEBA) were prepared for biobutanol recovery from acetone–butanol–ethanol (ABE) fermentation broth by pervaporation (PV). FESEM, EDS, XRD, FT-IR, DSC and contact angle measurements were conducted to study the morphologies, physical and chemical properties and surface properties of the MMMs. The PV performance of the prepared MMMs with various ZIF-71 loadings for separating n-butanol from its aqueous solution was investigated. As a result, both separation factor and thickness-normalized flux of the PEBA membranes were improved by incorporating appropriate amount of ZIF-71 (≤20wt%). The membrane with 20wt% ZIF-71 was evaluated in ABE model solution and ABE fermentation broth, and exhibited high n-butanol separation performance. ZIF-71 particles were confirmed as promising fillers to enhance the separation performance for butanol recovery because of their excellent compatibility with polymer and organophilicity. This work demonstrated the ZIF-71/PEBA MMMs could be potential candidates for practical biobutanol production.

Selective separation of biobutanol from acetone–butanol–ethanol fermentation broth by means of sorption methodology based on a novel macroporous resin

The traditional distillation method for recovery of butanol from fermentation broth is an energy-intensive process. Separation of butanol based on adsorption methodology has advantages in terms of biocompatibility and stability, as well as economy, and therefore gains much attention. However, the application of the commercial adsorbents in the integrated acetone-butanol-ethanol (ABE) fermentation process is restricted due to the low recovery (less than 85%) and the weak capability of enrichment in the eluent (3-4 times). In this study, we investigated the sorption properties of butanol onto three kinds of adsorbents with different polarities developed in our laboratory, that is, XD-41, H-511, and KA-I resin. The sorption behaviors of single component and ABE ternary mixtures presented in the fermentation broths on KA-I resin were investigated. KA-I resin had higher affinity for butanol than for acetone, ethanol, glucose, acetic acid, and butyric acid. Multicomponent ABE sorption on KA-I resin was modeled using a single site extended Langmuir isotherm model. In a desorption study, all the adsorbed components were desorbed in one bed volume of methanol, and the recovery of butanol from KA-I resin was 99.7%. The concentration of butanol in the eluent was increased by a factor of 6.13. In addition, KA-I resin was successfully regenerated by two bed volumes of water. Because of its quick sorption, high sorption capacity, low cost, and ease of desorption and regeneration, KA-I resin exhibits good potential for compatibility with future ABE fermentation coupled with in situ recovery product removal techniques.

Pervaporation performance of PDMS/ceramic composite membrane in acetone butanol ethanol (ABE) fermentation–PV coupled process

Pervaporation (PV) has attracted increasing attention owing to its potential application in biofuel recovery from biomass fermentation process. In this work, PDMS/ceramic composite membrane was directly coupled with acetone butanol ethanol (ABE) fermentation to in situ remove ABE solvents from the fermentation broth. The membrane PV performances and stability in the spent fermentation broth and fermentation–PV coupled process were systematically investigated. As observed in the ABE fermentation broth, the inorganic salts favored increasing the membrane selectivity whereas the microbial cells resulted in a reduced PV performance. Although a fluctuation of membrane performance was observed due to the occurrence of membrane fouling in the fermentation–PV coupled process, the PDMS/ceramic composite membrane exhibited a high flux of 0.670 kg/m 2 h and applicable ABE separation factor of 16.7. The SEM, AFM and FT-IR characterizations confirmed that the membrane fouling originated from the adsorption of active cells on the membrane surface. Nevertheless, the membrane fouling in the coupled process was reversible, with easy recovery of PV performance after a simple water rinse.

Pervaporation Separation of Butanol-Water Mixtures Using Polydimethylsiloxane/Ceramic Composite Membrane

Pervaporation has attracted considerable interest owing to its potential application in recovering biobutanol from biomass acetone-butanol-ethanol (ABE) fermentation broth. In this study, butanol was recovered from its aqueous solution using a polydimethylsiloxane (PDMS)/ceramic composite pervaporation membrane. The effects of operating temperature, feed concentration, feed flow rate and operating time on the membrane pervaporation performance were investigated. It was found that with the increase of temperature or butanol concentration in the feed, the total flux through the membrane increased while the separation factor decreased slightly. As the feed flow rate increased, the total flux increased gradually while the separation factor changed little. At 40°C and 1% (by mass) butanol in the feed, the total flux and separation factor of the membrane reached 457.4 g·m −2·h −1 and 26.1, respectively. The membrane with high flux is suitable for recovering butanol from ABE fermentation broth.

Acetone butanol ethanol (ABE) recovery by pervaporation using silicalite–silicone composite membrane from fed-batch reactor of Clostridium acetobutylicum

Acetone butanol ethanol (ABE) were produced in an integrated fermentation-product recovery system using Clostridium acetobutylicum ( C. acetobutylicum) and a silicalite–silicone composite membrane. Cells of C. acetobutylicum were removed from the cell culture using a 500,000 molecular weight cut-off ultrafiltration membrane and returned to the fed-batch fermentor. The ABE was removed from the ultrafiltration permeate using a silicalite–silicone composite pervaporation membrane. The silicalite–silicone composite membrane (306 μm thick) was made in our laboratory and characterized for flux and selectivities using model acetone ethanol butanol solution. Flux of the silicalite–silicone composite membrane was constant during pervaporation of fermentation broth at the same concentration of ABE. Acetone butanol selectivity was also not affected by the fermentation broth, indicating that the membrane was not fouled by the ABE fermentation broth. The silicalite–silicone composite membrane was exposed to fermentation broth for 120 h. Acetic acid and ethanol did not diffuse through the silicalite–silicone composite membrane at low concentrations. The fed-batch reactor was operated for 870 h. Totally 154.97 g/l solvents was produced at solvent yield of 0.31–0.35.

Fouling of poly[-1-(trimethylsilyl)-1-propyne] membranes in pervaporative recovery of butanol from aqueous solutions and ABE fermentation broth

Poly[1-(trimethylsilyl)-1-propyne] (PTMSP) dense films were evaluated for n-butanol recovery from aqueous solutions and acetone–butanol–ethanol (ABE) fermentation broth. Flux decline through PTMSP dense films due to polymer compaction under vacuum conditions, relaxation in alcohol and alcohol/water mixtures, and membrane contamination are discussed. Flux decline of a PTMSP film during pervaporation of 20 g/l BuOH/water mixture was fitted to the following function, y= At − b . PTMSP films change their geometry when exposed to alcohol and alcohol/water mixtures and then dried. As a result of the relaxation process, polymer film becomes thicker and denser, effecting membrane performance. PTMSP films that were treated with 70% iso-propanol/water show linear flux decline versus pervaporation time. Strong lipid adsorption seems to occur on the membrane surface when fermentation broth is used as a feed causing flux decline within short period of time.