Extraction of butyric acid with a solvent containing ammonium ionic liquid

Reactive extraction of muconic acid by hydrophobic phosphonium ionic liquids - Experimental, modelling and optimisation with Artificial Neural Networks

Muconic acid is a six-carbon dicarboxylic acid with conjugated double bonds that finds extensive use in the food (additive), chemical (production of adipic acid, monomer for functional resins and bio-plastics), and pharmaceutical sectors. The biosynthesis of muconic acid has been the subject of recent industrial and scientific attention. However, because of its low concentration in aqueous solutions and high purity requirement, downstream separation presents a significant problem. Artificial Neural Networks and Differential Evolution were used to optimize process parameters for the recovery of muconic acid from aqueous streams in a system with n-heptane as an organic diluent and ionic liquids as extractants. The system using 120 g/L tri-hexyl-tetra-decyl-phosphonium decanoate dissolved in n-heptane, pH of the aqueous phase 3, 20 min contact time, and 45 °C temperature assured a muconic acid extraction efficiency of 99,24 %. Low stripping efficiency compared to extraction efficiency was observed for the optimum conditions on the extraction step (120 g/L ionic liquids dissolved in heptane). However, re-extraction efficiencies obtained for the recycled organic phase in three consecutive stages were close to the first extraction stage. The mechanism analysis proved that the analysed phosphonium ionic liquids (PILSs) extracts only undissociated molecules of muconic acid through H-bonding.

Folic Acid Ionic-Liquids-Based Separation: Extraction and Modelling

Folic acid (vitamin B9) is an essential micronutrient for human health. It can be obtained using different biological pathways as a competitive option for chemical synthesis, but the price of its separation is the key obstacle preventing the implementation of biological methods on a broad scale. Published studies have confirmed that ionic liquids can be used to separate organic compounds. In this article, we investigated folic acid separation by analyzing 5 ionic liquids (CYPHOS IL103, CYPHOS IL104, [HMIM][PF₆], [BMIM][PF₆], [OMIM][PF₆]) and 3 organic solvents (heptane, chloroform, and octanol) as the extraction medium. The best obtained results indicated that ionic liquids are potentially valuable for the recovery of vitamin B9 from diluted aqueous solutions as fermentation broths; the efficiency of the process reached 99.56% for 120 g/L CYPHOS IL103 dissolved in heptane and pH 4 of the aqueous folic acid solution. Artificial Neural Networks (ANNs) were combined with Grey Wolf Optimizer (GWO) for modelling the process, considering its characteristics.

Applications of Ionic Liquids in Carboxylic Acids Separation

Ionic liquids (ILs) are considered a green viable organic solvent substitute for use in the extraction and purification of biosynthetic products (derived from biomass-solid/liquid extraction, or obtained through fermentation-liquid/liquid extraction). In this review, we analyzed the ionic liquids (greener alternative for volatile organic media in chemical separation processes) as solvents for extraction (physical and reactive) and pertraction (extraction and transport through liquid membranes) in the downstream part of organic acids production, focusing on current advances and future trends of ILs in the fields of promoting environmentally friendly products separation.

Energy-efficient recovery of fermented butyric acid using octyl acetate extraction

Background

A butyric acid recovery process using octyl acetate is proposed, and the design details of the extraction and subsequent distillation processes were investigated. Ternary equilibrium data for the extractor design were derived from molecular simulations and experimental measurements.

Results

A new procedure for estimating the thermodynamic parameters was introduced to determine the effect of the parameters on extractor design by comparison with previously reported parameters. Using the proposed recovery process with the newly estimated thermodynamic model, 99.8% butyric acid was recovered from the fermentation broth at a recovery rate of 99%. The energy demand for the proposed process was found to be lower than the average demand for several reported butyric acid recovery processes.

Conclusions

The investment cost is projected to be lower than that of other butyric acid processes due to the high efficiency of extraction solvent. The recovery cost of butyric acid was comparable to its selling price.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13068-022-02146-6.

Ionic liquid-assisted biphasic systems for downstream processing of fermentative enzymes and organic acids

Room-temperature ionic liquids (ILs) represent molten salts entirely consisting of ions, usually a charge-stabilized organic cation and an inorganic or organic anion. ILs are liquids at ambient temperature but possess characteristics unusual for the common liquid solvents, such as negligible vapor pressure, high thermal stability and most over the ability to mix and match libraries of cations and anions in order to acquire desirable physical and chemical properties [1]. The opportunity to obtain tunable density, viscosity, polarity and miscibility with common molecular liquids gave rise to a variety of applications of the ILs [2] as environmentally benign solvents, extractants or auxiliaries. In particular, numbers of innovations in the methods for recovery and purification of biologically derived compounds involve ILs used solo or partnered with other liquids in biphasic systems [3,4,5]. It should be noted that the ILs are not intrinsically greener than the traditional solvents, given that their production is usually more resource-demanding, but the inherent potential for recycling and reuse, and for prevention of chemical accidents gives the ILs advantages ahead.

The present chapter provides a state-of-the-art overview on the basic applications of the ILs in biphasic systems aimed at downstream processing of valuable fermentative products, enzymes and organic acids. Main industrially important enzymes, lipases and carbohydrases, are considered and a description of the IL-assisted aqueous biphasic systems (ABS) and the results obtained in view of enzyme yield and purity is made. ILs serve different functions in the ABS, main phase-segregating constituents (mostly in the IL/salt ABS) or adjuvants to the polymer/salt ABS. Enzyme isolation from the contaminant proteins present in the feedstock can be carried out either in the IL-rich or in the salt-rich phase of the ABS and for the reader’s convenience the two options are described separately. Discussion on the factors and parameters affecting the enzyme partitioning in the ABS with ILs guides the reader through the ways by which the interactions between the IL and the enzyme can be manipulated in favor of the enzyme purification through the choice of the ABS composition (IL, salt, pH) and the role of the water content and the IL-rich phase structure.

The second part of the chapter is dedicated to the recovery of fermentative organic acids. Mostly hydrophobic ILs have been engaged in the studies and the biphasic systems thereof are summarized. The systems are evaluated by the extraction efficiency and partition coefficient obtained. Factors and parameters affecting the extraction of organic acids by ILs are highlighted in a way to unravel the extraction mechanism. The choice of IL and pH determines the reactive mechanism and the ion exchange, while the water content and the IL phase structure play roles in physical extraction. Procedures undertaken to enhance the efficiency and to intensify the process of extraction are also looked over.

Finally, the experimental holes that need fill up in the future studies are marked. According to the author’s opinion an intense research with hydrophobic ILs is suggested as these ILs have been proved milder to the biological structures (both the microbial producer and the enzyme product), more effective in the organic acid recovery and suitable to perform “in situ” extraction. Extractive fermentation entails validation of ecological and toxicological characteristics of the ILs. The protocols for re-extraction of fermentative products separated by IL-assisted biphasic systems should be clearly settled along with the methods for ILs recycling and reuse. Novel more flexible approaches to process intensification can be implemented in order to adopt the separation by biphasic systems for use in industry.

Influence of Anion and Cation Structure of Ionic Liquids on Carboxylic Acids Extraction

A recently proposed new mechanism and a model of reactive extraction of carboxylic acids by hydrophobic ionic liquids (ILs) was tested on five systems from published as well as from new equilibrium data on liquid-liquid extraction of butyric and lactic acids (BA and LA) from aqueous solutions. Two phosphonium and one ammonium ILs were used. The model describes experimental data for all systems with a good fit. The mechanism of acid extraction by ILs is very similar for all tested systems. This indicates a more general validity of the developed model. The model allows deeper understanding of regularities in carboxylic acid extraction by hydrophobic ILs. Stability constants of the first acid-IL bonds are by one to three orders of magnitude higher compared to that of acid-acid bonds. Values of stability constants related to two acid-IL bonds are sensitive to a cation and anion structure while stability constants for acid-acid bonds more distant from polar head of IL are not sensitive to IL structure. The stability constants of acid-IL bonds for LA and phosphonium ILs are by more than one order of magnitude lower compared to those for BA and are not influenced with an anion structure. The value of stability constant for the first BA-IL bond is for phosphonium IL with a decanoate anion only one third of those for IL with a phosphinate anion. Differences in the stability of acid-IL bonds for BA and LA can be attributed to hydrophobic interactions which almost do not occur in LA extraction. Ammonium IL also forms a less stable BA-IL bond than the phosphonium IL with the same phosphinate anion. A less stable BA-IL bond can favor the higher recovery of volatile acid from the solvent by vacuum evaporation where free acid is separated instead of acid salts as in classical processes what is a great advantage.

A step forward in the development ofin situproduct recovery by reactive separation of protocatechuic acid

A conceptual design of an ISPR configuration for the biosynthesis, separation, and recovery of PCA by reactive extraction with TBP in natural non-toxic diluents.

Recovery of Volatile Fatty Acids from Fermented Wastewater by Adsorption

Separation of volatile fatty acids (VFAs) from fermented wastewater is challenging, due to low VFA concentrations in mineral-rich streams. As a result, separation capacity and selectivity with traditional solvents and adsorbents are both compromised. In this study, using a complex artificial model solution mimicking real fermented wastewaters, it is shown that a simple and robust adsorption-based separation technique can retain a remarkable capacity and selectivity for VFAs. Four types of polystyrene-divinylbenzene-based resins (primary, secondary, and tertiary amine-functionalized, and nonfunctionalized) were examined as the adsorbents. The presence of chloride, sulfate, and phosphate salts resulted in coadsorption of their acidic forms HCl, H₂SO₄, and H₃PO₄ on amine-functionalized adsorbents, and severely reduced the VFA capacity. With the nonfunctionalized adsorbent, almost no mineral acid coadsorption was observed. This together with a high total VFA capacity of up to 76 g/kg in equilibrium with the model solution containing a total VFA concentration of 1 wt % resulted in a very high selectivity for the VFAs. Nitrogen-stripping with various temperature profiles was applied to regenerate the adsorbent, and study the potential for fractionation of the VFAs during regeneration. Butyric acid (HBu) was obtained in mole fractions of up to 0.8 using a stepwise increase in the stripping temperature from 25 °C via 120 to 200 °C. During four successive adsorption-regeneration cycles, no reduction in the adsorption capacity was observed.

Recent progress on deep eutectic solvents in biocatalysis

Deep eutectic solvents (DESs) are eutectic mixtures of salts and hydrogen bond donors with melting points low enough to be used as solvents. DESs have proved to be a good alternative to traditional organic solvents and ionic liquids (ILs) in many biocatalytic processes. Apart from the benign characteristics similar to those of ILs (e.g., low volatility, low inflammability and low melting point), DESs have their unique merits of easy preparation and low cost owing to their renewable and available raw materials. To better apply such solvents in green and sustainable chemistry, this review firstly describes some basic properties, mainly the toxicity and biodegradability of DESs. Secondly, it presents several valuable applications of DES as solvent/co-solvent in biocatalytic reactions, such as lipase-catalyzed transesterification and ester hydrolysis reactions. The roles, serving as extractive reagent for an enzymatic product and pretreatment solvent of enzymatic biomass hydrolysis, are also discussed. Further understanding how DESs affect biocatalytic reaction will facilitate the design of novel solvents and contribute to the discovery of new reactions in these solvents.

Increased biohydrogen yields, volatile fatty acid production and substrate utilisation rates via the electrodialysis of a continually fed sucrose fermenter

Electrodialysis (ED) removed volatile fatty acids (VFAs) from a continually-fed, hydrogen-producing fermenter. Simultaneously, electrochemical removal and adsorption removed gaseous H₂ and CO₂, respectively. Removing VFAs via ED in this novel process increased H₂ yields by a factor of 3.75 from 0.24molH₂mol^-1_hexose to 0.90molH₂mol^-1_hexose. VFA production and substrate utilisation rates were consistent with the hypothesis that end product inhibition arrests H₂ production. The methodology facilitated the recovery of 37g of VFAs, and 30L H₂ that was more than 99% pure, both of which are valuable, energy dense chemicals. Typically, short hydraulic and solid retention times, and depressed pH levels are used to suppress methanogenesis, but this limits H₂ production. To produce H₂ from real world, low grade biomass containing complex carbohydrates, longer hydraulic retention times (HRTs) are required. The proposed system increased H₂ yields via increased substrate utilisation over longer HRTs.

Removal and recovery of inhibitory volatile fatty acids from mixed acid fermentations by conventional electrodialysis

Hydrogen production during dark fermentation is inhibited by the co-production of volatile fatty acids (VFAs) such as acetic and n-butyric acid. In this study, the effectiveness of conventional electrodialysis (CED) in reducing VFA concentrations in model solutions and hydrogen fermentation broths is evaluated. This is the first time CED has been reported to remove VFAs from hydrogen fermentation broths. During 60 min of operation CED removed up to 99% of VFAs from model solutions, sucrose-fed and grass-fed hydrogen fermentation broths, containing up to 1200 mg l(-1) each of acetic acid, propionic acid, i-butyric acid, n-butyric acid, i-valeric acid, and n-valeric acid. CED's ability to remove VFAs from hydrogen fermentation broths suggests that this technology is capable of improving hydrogen yields from dark fermentation.