Reactive Liquid-liquid Extraction Research Articles

Reactive liquid-liquid extraction of lactic acid from microfiltered sweet sorghum silage press juice in an agitated extraction column using a hydrophobic natural deep eutectic solvent as modifier

Downstream processing of carboxylic acids from fermentation broths is cost-intensive and environmentally harmful, which makes methods such as reactive liquid-liquid extraction attractive separation technologies. To enhance the sustainability of liquid-liquid extraction processes, research focuses on sustainable solvents like hydrophobic natural deep eutectic solvents. However, the application of hydrophobic natural deep eutectic solvents in agitated extraction columns for continuous processing has never been investigated. This is essential to facilitate their use in industrial processes, promoting cleaner production. In this study, the application of a thymol-menthol-based deep eutectic solvent as a modifier (with the extractant tri-n-octylamine) in an agitated extraction column is evaluated for reactive liquid-liquid extraction of lactic acid from microfiltered sweet sorghum silage press juice. In addition, three-stage cross-current extractions were performed. The thymol-menthol-based deep eutectic solvent showed efficient phase separation, stable operation, and chemical stability in the agitated extraction column. In three-step cross-current operation, the extraction efficiency for lactic acid was increased from 37.0 ± 0.4 % without feed pH adjustment to 76.2 ± 0.9 % with continuously adjusting the pH value to 2.05 ± 0.02. The thymol-menthol-based deep eutectic solvent shows great potential for application in agitated extraction columns. This is highly promising because natural deep eutectic solvents can enhance the sustainability of extraction processes and reduce the reliance on fossil-based solvents.

Mineral Acid Co-Extraction in Reactive Extraction of Lactic Acid Using a Thymol-Menthol Deep Eutectic Solvent as a Green Modifier.

Carboxylic acids can be isolated from fermentation broths using reactive liquid-liquid extraction, offering an alternative to the environmentally harmful state-of-the-art process of precipitating calcium lactate. To enhance the sustainability of liquid-liquid extraction processes, greener solvents, such as natural deep eutectic solvents, are investigated. However, fermentation broths often exhibit pH values unsuitable for carboxylic acid extraction, which can be adjusted using mineral acids, though mineral acids may be co-extracted. In this study, we systematically examine the co-extraction of hydrochloric, nitric, sulfuric, and phosphoric acid during extraction and back-extraction of lactic acid. The solvent phase consisted of tri-n-octylamine, trioctylphosphine oxide, or tributyl phosphate diluted in a thymol-menthol deep eutectic solvent. The back-extraction was conducted using a diluent swing with p-cymene as the antisolvent and water as the receiving phase. Tri-n-octylamine showed the highest efficiency for lactic acid (up to 29.8%) but also the highest co-extraction of mineral acids (up to 50.9%). In contrast, trioctylphosphine oxide exhibited a lower but more selective lactic acid extraction (5.94%) with low mineral acids co-extraction (0.135%). Overall, the highest co-extraction was observed for phosphoric acid and the lowest for nitric acid. In conclusion, the selected solvent phase composition and mineral acid influence the co-extraction and, thus, final product purity. The successful application of the natural deep eutectic solvent as the modifier enhances the sustainability of liquid-liquid extraction processes.

(Selective) Isolation of acetic acid and lactic acid from heterogeneous fermentation of xylose and glucose

The present study focuses on the isolation of acetic and lactic acid from a fermentation broth produced by heterofermentative microorganisms using glucose and xylose as substrate. Especially xylose fermentation to lactic acid leads to unwanted by-product formation of acetic acid. Reactive liquid-liquid extraction is an energy-efficient downstream process, where the use of green solvents such as d-limonene opens the way to a more sustainable production. To find the optimum solvent/reactive extractant pairing, the reactive extractants trioctylamine, trioctylphosphine oxide, Aliquat 336, and tributyl phosphate were used diluted in 1-octanol, 1-decanol, d-limonene or a deep eutectic solvent. The phosphine-based extractants proved to be most effective for both acids. In the first extraction step, 19% of acetic acid and only 3% of lactic acid are extracted with trioctylphosphine oxide/1-octanol when the xylose feed is used without pH adjustment. The pKa value of the acids is responsible for the difference in extraction efficiency leading to the proposal of a two-step extraction separating first acetic acid and after pH adjustment, lactic acid can be extracted. The combination of trioctylphosphine oxide diluted in d-limonene leads to a surprisingly high selectivity for lactic acid isolation in the second extraction step. The present study shows for the first time that green solvents lead to similar extraction efficiencies compared to conventional solvents such as 1-octanol. For back extraction n-heptane and p-cymene are used as disintegration agents and water as stripping phase; n-heptane results in a lactic acid back extraction efficiency of up to 82% and p-cymene up to 70%. This shows that also for the back extraction p-cymene as a green disintegration agent leads to similar results as fossil-based n-heptane.

Purification and concentration of formic acid from formic acid/gluconic acid mixtures by two successive steps of nanofiltration and reactive liquid-liquid extraction

A downstream process for the purification and concentration of formic acid (FA) from FA/gluconic acid (GA) mixtures, obtainable by a coupled biocatalytic reaction of CO2 reduction and glucose oxidation, has been developed. The process involved two technologies: (i) a first nanofiltration (NF) step to separate FA and GA, and (ii) a second reactive liquid-liquid extraction (RLLE) step to concentrate FA. The NF process, using a Synder NFX membrane, consisted of three NF steps separated into two divergent lines, named permeate and retentate pathways. The first NF was common for both pathways, resulting in a permeate strongly enriched in FA and depleted in GA, and a retentate with opposite characteristics. In the permeate pathway, this first permeate was subjected to a second NF to obtain a 99.6% pure FA permeate. In the retentate pathway, an additional NF step on the first retentate resulted in a concentrated 99.4% pure GA retentate. The final diluted FA permeate was concentrated by RLLE using tri-N-octylamine as extractant in n-octanol, and a final back-extraction with NaOH. The optimized RLLE process involved a 100-fold volume decrease and resulted in a final FA solution (as sodium formate) of 174.5 g/L, 78 times more concentrated than the feed.

Reactive Liquid-Liquid Extraction of Bio-Based 3-Hydroxypropionic Acid Using a Biocompatible Organic Phase Containing a Tertiary Amine: A Model-Based Approach to Elucidate Dominant Mechanisms

Reactive Liquid-Liquid Extraction of Bio-Based 3-Hydroxypropionic Acid Using a Biocompatible Organic Phase Containing a Tertiary Amine: A Model-Based Approach to Elucidate Dominant Mechanisms

Thymol-Menthol-Based Deep Eutectic Solvent to Replace 1‑Octanol as Modifier in Reactive Liquid-Liquid Extraction of Lactic Acid, Acetic Acid and Oxalic Acid from Pretreated Sweet Sorghum Silage Press Juice

Thymol-Menthol-Based Deep Eutectic Solvent to Replace 1‑Octanol as Modifier in Reactive Liquid-Liquid Extraction of Lactic Acid, Acetic Acid and Oxalic Acid from Pretreated Sweet Sorghum Silage Press Juice

Special designed menthol-based deep eutectic liquid for the removal of herbicide 2,4-dichlorophenoxyacetic acid through reactive liquid–liquid extraction

Reactive liquid–liquid extraction (RLLE) was applied for the removal of 2,4-dichlorophenoxyacetic acid (2,4-D) from its aqueous solution. Deep eutectic liquids (DELs) was used as extractant in a conventional solvent (diethyl succinate-DES) through RLLE. Various menthol-based DELs were prepared. Menthol was used as hydrogen bond acceptor, whilst formic acid and acetic acid were hydrogen bond donor for the DEL preparations. The best 2,4-D removal was achieved by menthol/formic acid (1/2, molar ratio) combination. The menthol-based DEL increased the extraction performance of DES by almost 2–3 times. More than 90% of 2,4-D were extracted by the recommended method with the designed solvent. Thermodynamics study has been also executed. Thermodynamics of the 2,4-D transfer from aqueous phase to hydrophobic phase has been found to be spontenous and endothermic process, which is incentived by entropy. Moreover, Fourier transformed infrared-attenuated total reflectance was used for the characterization reasons of the prepared DELs. Additionally, physical properties such as pH, density, viscosity and refractive index of the products were also measured. The last but not the least, viscosity and acidity of the extraction medium were found to be effective parameters.

Menthol-based deep eutectic solvent for the separation of carbamazepine: reactive liquid-liquid extraction

Menthol-based deep eutectic liquid has been used for the reactive liquid-liquid extraction of the carbamazepine from its aqueous solution after it was synthesized by heating and mixing. Diethyl succinate was used as diluent, while deep eutectic liquid was the extractant. Several deep eutectic liquids containing menthol and carboxylic acids (acetic acid and formic acid) with different molar ratios (1/1 and 1/2) were composed. pH, density, viscosity, and refractive index values of the designed deep eutectic liquids were measured. Furthermore, Fourier transform infrared spectroscopy method was also applied into the deep eutectic liquids for characterization. Deep eutectic liquid increased the extraction performance of the diluent from 11 to 36% comparing to the untreated one. The proposed system (menthol/acetic acid with 1/1 of molar ratio) has extracted more than 90% of the target pharmaceutical compound from its aqueous solution in 30 min. The concentration of extractant in the diluent, initial carbamazepine content in aqueous media, and ionic intensity have influenced the reactive liquid-liquid extraction. Depending on the thermodynamics outcome, the transfer process of carbamazepine from aqueous phase into hydrophobic phase is an endothermic and spontaneous in nature. It has been also observed to be a separation process with a structure that tends to be irregular.

Kinetic evaluation of simultaneous waste cooking oil hydrolysis and reactive liquid-liquid Cu extraction from synthetic Cu-containing wastewater: Effect of various co-contaminants

Abstract Combination of oil hydrolysis reaction and reactive liquid-liquid extraction of Cu 2+ from wastewater offers economic and environmental advantage than running two processes separately. To give better insight on the application of the proposed process to treat real wastewater, the effects of other pollutants (acid/base, chelating agents, organic solvent, anions) present in the synthetic Cu-containing wastewater were studied. The reaction was carried out in a batch reactor using a water/acylglycerides molar ratio of 30:1 at 225 °C up to 8 h to understand the effect of the studied parameters during the reaction time course. It was found that pH influenced acid/base balance, which governs catalysis and Cu-soap formation in subcritical water. Chelating agents formed strong complexation with Cu 2+ that changed Cu removal mechanism from cation exchange reaction to that of conventional solvent extraction. The presence of organic solvents affected the dielectric constant of water that shifted the equilibrium of cation exchange reaction towards lipophilic Cu soap formation. Different anion type produced different type of acid by means of the cation exchange mechanism that influenced acid catalysis and Cu-soap formation. Other heavy metal cations expressed the same cation exchange mechanism and catalysis ability as that of Cu 2+ .

New insights in reactive extraction mechanisms of organic acids: An experimental approach for 3-hydroxypropionic acid extraction with tri-n-octylamine

A detailed study of 3-hydroxypropionic acid (3-HP) reactive extraction with tri-n-octylamine (TOA) is proposed for the first time. It aims at uncovering some solvent-solutes interactions and providing global mechanisms to better understand and design the reactive liquid-liquid extraction of 3-HP in a biotechnological process. Eleven solvents of similar molecular sizes and several chemical types (alcohols, esters and alkanes) were investigated to understand their role on the extraction ability. Alcohols were found to be the best solvents thanks to their H-bond donor characteristic and water loading that allowed good solvation of the acid-amine complexes. Further investigations were then undertaken, for n-decanol and oleyl alcohol as solvents, varying acid (0.0028-0.56 mol/L corresponding to 0.25-50 g/L) and amine (02,3 corresponding to 0-100% v/v) concentrations. At 0.011 mol/L (1 g/L) of 3-HP, maximum extraction yields of 77% for n-decanol and 51% for oleyl alcohol were found for 0.46 mol/L TOA (20% v/v). The initial TOA purity proved to have a major impact on the extraction yield at low initial acid concentration (<0.1 mol/L = 10 g/L). Impurities from the TOA manufacturing process were identified as n-octylamine and di-n-octylamine and quantified in the aqueous phase after extraction. Their major effect on the extraction yield has been assessed (up to 86% decrease).

A microfluidic study of liquid–liquid extraction mediated by carbon dioxide

Liquid-liquid extraction is an important separation and purification method; however, it faces a challenge in reducing the energy consumption and the environmental impact of solvent (extractant) recovery. The reversible chemical reactions of switchable solvents (nitrogenous bases) with carbon dioxide (CO2) can be implemented in reactive liquid-liquid extraction to significantly reduce the cost and energy requirements of solvent recovery. The development of new effective switchable solvents reacting with CO2 and the optimization of extraction conditions rely on the ability to evaluate and screen the performance of switchable solvents in extraction processes. We report a microfluidic strategy for time- and labour-efficient studies of CO2-mediated solvent extraction. The platform utilizes a liquid segment containing an aqueous extractant droplet and a droplet of a solution of a switchable solvent in a non-polar liquid, with gaseous CO2 supplied to the segment from both sides. Following the reaction of the switchable solvent with CO2, the solvent becomes hydrophilic and transfers from the non-polar solvent to the aqueous droplet. By monitoring the time-dependent variation in droplet volumes, we determined the efficiency and extraction time for the CO2-mediated extraction of different nitrogenous bases in a broad experimental parameter space. The platform enables a significant reduction in the amount of switchable solvents used in these studies, provides accurate temporal characterization of the liquid-liquid extraction process, and offers the capability of high-throughput screening of switchable solvents.

A study of parameters affecting the solvent extraction of lactic acid from fermentation broth

Lactic acid has recently been drawing much interest as a raw material for biodegradable polymer. One of the promising technologies for recovery of lactic acid from fermentation broth is reactive liquid-liquid extraction. Equilibrium studies on the reactive extraction of lactic acid with trioctylamine (TOA) in various organic phases and its re-extraction into aqueous solutions were carried out. In this study distribution coeffi- cient, extractability, stripping efficiency of various active and inert diluents with TOA as extractant were investigated, which were higher for active diluents. The effects of operating temperature, speed of agitation, agitation time and diluent composition on extraction efficiency were also studied. Temperature and extraction efficiency were inversely proportional to each other, whereas extraction efficiency was little affected by speed of agitation and agitation time.

3,3′-diaryl-BINOL phosphoric acids as enantioselective extractants of benzylic primary amines

We report that 3,3'-diaryl-BINOL phosphoric acids are effective enantioselective extractants in chiral separation methods based on reactive liquid-liquid extraction. These new extractants are capable of separating racemic benzylic primary amine substrates. The effect of the nature of the substituents at the 3,3'-positions of the host were examined as well as the structure of the substrate, together with important parameters such as the organic solvent, the pH of the aqueous phase, and the host stoichiometry. Titration of the substrate with the host was monitored by FTIR, NMR, UV-Vis, and CD spectroscopy, which provided insight into the structure of the host-guest complex involved in extraction.

Effects of Organic Phase, Fermentation Media, and Operating Conditions on Lactic Acid Extraction

Lactic acid has extensive uses in the food, pharmaceutical, cosmetic and chemical industry. Lately, its use in producing biodegradable polymeric materials (polylactate) makes the production of lactic acid from fermentation broths very important. The major part of the production cost accounts for the cost of separation from very dilute reaction media where productivity is low as a result of the inhibitory nature of lactic acid. The current method of extraction/separation is both expensive and unsustainable. Therefore, there is great scope for development of alternative technology that will offer efficiency, economic, and environmental benefits. One of the promising technologies for recovery of lactic acid from fermentation broth is reactive liquid-liquid extraction. In this paper the extraction and recovery of lactic acid based on reactive processes is examined and the performance of a hydrophobic microporous hollow-fiber membrane module (HFMM) is evaluated. First, equilibrium experiments were conducted using organic solutions consisting of Aliquat 336/trioctylamine (as a carrier) and tri-butyl phosphate (TBP)/sunflower oil (as a solvent) The values of the distribution coefficient were obtained as a function of feed pH, composition of the organic phase (ratio of carrier to solvent), and temperature (range 8-40 degrees C). The optimum extraction was obtained with the organic phase consisting of a mixture of 15 wt % tri-octylamine (TOA) and 15% Aliquat 336 and 70% solvent. The organic phase with TBP performed best but is less suitable because of its damaging properties (toxicity and environmental impact) and cost. Sunflower oil, which performed moderately, can be regarded as a better option as it has many desirable characteristics (nontoxic, environment- and operator-friendly) and it costs much less. The percentage extraction was approximately 33% at pH 6 and at room temperature (can be enhanced by operating at higher temperatures) at a feed flow rate of 15-20 L/h. These results suggest that the hollow-fiber membrane process yields good percentage extraction at the fermentation conditions and its in situ application could improve the process productivity by suppressing the inhibitory effect of lactic acid.

Separation of Heavy Metals from Landfill Leachate by Reactive Liquid-Liquid Extraction

The objective of this work was to investigate the decontamination of a model landfill leachate by simultaneous separation of heavy metals from alkaline earth metals and iron in order to obtain a leachate that can be led back to the landfill. Reactive extraction as a separation process offers the possibility of selectively separating cations, that is, of separating toxic components from less problematic ones, and also includes the possibility of electrolysis and further processes to obtain the desired metals.

New generation tools for multiphase reaction systems: A validated systematic methodology for novelty and design automation

An overall methodology is presented for the early screening and scoping of the promising reactor designs for the multiphase reaction systems. The reactor designs are screened with a systematic methodology based on a novel representation and a reliable optimization approach. The work significantly extends previous efforts in homogeneous systems and the stochastic optimization adopted in this work is able to handle typical complexities. The paper also discusses ways of finding optimum network of non-isothermal reactors. A comprehensive representation and a suitable methodology for the purpose are discussed. Optimum temperature profiles are evaluated without restriction to any particular mode of heat transfer. A network of adiabatic reactors with intermediate heat exchangers and both direct and indirect heat transfers is also presented. The method is taking up applications in industry and is illustrated here with an example of reactive liquid-liquid extraction with multiple reversible reactions. The application of the approach to non-isothermal systems is illustrated with a simple van de Vusse type of reaction. The overall methodology can be used as a targeting tool to find the limiting performance of the reaction systems as well as to evaluate the network of ideal reactors, which can achieve this performance.

Reactive liquid-liquid extraction of heavy metals from leachate with oil-soluble complexing surfactants

Reactive liquid-liquid extraction is a well-known technology for the selective winning of metals. However, the application of this method in environmental processing, such as the non-selective separation of heavy metals from waste water (e.g. leachate from landfills), is new. It is shown that technical oil-soluble surfactants with complexing properties are able to lower the content of simultaneously present heavy metals by about two or three orders of magnitude, starting at 10–100 mg 1 −1. By applying commercially available quinolines (such as LIX26 ®) and oximes (such as LIX84 ®), it is possible to extract the heavy metals Cu, Cr, Cd, Ni, Zn and Pb in one step, keeping within the limits set by the German authorities. Bulk metals such as Ca remain in the waste water. Besides fundamental investigations on the stoichiometry of the extracting reaction, the extraction selectivity and the phase separation, experiments concerning the extraction and re-extraction speed using a continuously operating mixer-settler were performed.