Article

Green solvents selection guide for bio-based organic acids recovery

Authors:
To read the full-text of this research, you can request a copy directly from the authors.

Abstract

Bio-based organic acids constitute an important group of building block chemicals that can be produced from renewable resources, becoming a sustainable alternative to conventional petrochemical-derived commodities. However, due to the growing number of green solvents emerging as extraction media, the proper solvent selection for biomolecule separation from fermentation broths has become a key challenge in the bio-refinery industry. The overall aim of this work is to develop a roadmap to select and design green solvents for sustainable downstream processing of bio-based organic acids. To this end, a wide range of neoteric solvents (ionic liquids, eutectic solvents and bio-based solvents) were systematically evaluated for the recovery of relevant bio-organic acids through combination of experimental and COSMO-RS molecular simulation methods. Comprehensive thermodynamic analyses evaluating the organic acid partition coefficients, excess enthalpy contributions, solvent-water affinity, and process spontaneity were performed to elucidate the main mechanism driving the separation process and to provide essential guidelines for further solvent development. Based on these findings, a rational screening approach was established to identify suitable solvents for the recovery of structurally different bio-organic acids. Ultimately, this paper provides a green solvent selection guide to design sustainable separation processes of bio-based organic acids, as valuable platform chemicals transitioning towards a bio-based economy.

No full-text available

Request Full-text Paper PDF

To read the full-text of this research,
you can request a copy directly from the authors.

... In this sense, Liquid-Liquid extraction (L-L) is an energy-efficient separation technology that could enable the selective separation of LA from aqueous streams also containing FA. Previous works have demonstrated the ability of this technology in the extraction of LA and other organic acids from aqueous solutions [17][18][19][20][21][22]. Despite the capability of the liquid-liquid extraction technology in the recovery of LA, other works have also pointed out to the reactive extraction of these organic, which combines the physical and the chemical extraction and yields high distribution ratios [23]. ...
... However, Badgujar et al. [43] conducted an extensive review on these topics and included the downstream processes of purification of LA, proposing the direct contact of the IL + LA phase with an organic phase including a solvent evaporation. Finally, the work of Lopez-Porfiri et al. [21] provides a guide on the selection of IL and other green solvents for the extraction of organic acids including LA by means of COSMO-RS analysis and experimental work. The results clearly show that [Tf2N] -based ILs are recommended for the extraction of LA from aqueous solutions. ...
... A good example of this fact was given by Wazlo et al. [63]. Thus, the work of Lopez-Porfiri [21] and Villar et al. [40] provides a qualitative approach for the selection of ILs for LA extraction. ...
Article
The separation of Levulinic (LA) acid and Formic acid (FA) from aqueous streams represents an important and challenging separation in biorefineries, where ionic liquids (ILs) provide a sustainable environment for liquid-liquid extractions of these acids. In this work, a COSMO-RS screening of bis (trifluoromethylsulfonil)imide [Tf2N]⁻ based IL was first conducted and then followed by experimental validation to search for the most suitable cation for this separation. After the screening, ternary liquid-liquid equilibrium experiments at 298.15K and the subsequent data correlation using the Non-Random Two Liquid model (NRTL) were performed for future industrial implementation. Results indicated that the phosphonium cations, especially the trihexylthetradecyl phosphonium cation [P66614]⁺, produced the highest selectivity rates among all the experimentally measured ILs.
... HES were first introduced by van Osch et al. [27] in 2015, consisting of decanoic acid (HBD) and a quaternary ammonium salt (HBA), to be used as extractants of volatile fatty acids. Since then, numerous HES have been proposed and used for the extraction of different solutes [28,29], including the extraction of phenolic compounds from aqueous phases [30][31][32]. In 2018, Florindo et al. [33] proposed a novel HES to be used for the extraction of Bisphenol-A from aqueous solutions, by combining exclusively natural carboxylic acids, which can act both as hydrogen bond donors and acceptors. ...
... Likewise, sustainable production of biodiesel through enhanced lipid extraction from microalgae using 2MeTHF has been successfully demonstrated [43]. Besides, 2MeTHF has also been proposed as an efficient solvent for the extraction of organic acids from diluted aqueous solutions [29,44]. Hence, based on the available literature, 2MeTHF looks very promising as an alternative to traditional petroleum-derived solvents for extraction. ...
Article
Integrated biorefineries are the current trend to produce energy, biochemicals and biofuels. A variety of sugar-rich biorefinery streams can be further valorized by fermentation, but the presence of inhibitory compounds hinders the fermentation yields. This paper proposes a detoxification method by selective liquid extraction of phenolic compounds using sustainable solvents to improve the fermentation of sugar-rich aqueous streams. Specifically, three hydrophobic eutectic solvents constituted by binary mixtures of octanoic, decanoic or dodecanoic acid (octanoic: decanoic acid 1:1, octanoic: dodecanoic acid 3:1, decanoic: dodecanoic acid 2:1) and three bio-based solvents (2-methyltetrahydrofuran, cyclopentyl methyl ether and limonene) were selected to analyze their capacity to extract representative phenolic compounds (phenol, o-cresol, guaiacol, syringol and vanillin) from aqueous solutions. Extraction efficiencies of individual compounds and mixtures of them were evaluated at different concentrations and temperatures using the proposed solvents. Finally, the liquid extraction of a solution containing 500 mg/L of phenolic compounds and 50 g/L of glucose, as a representative concentration in biorefinery streams, was performed. The distribution of the target compounds in each phase after the extraction process was analyzed by HPLC-DAD in the case of phenolic compounds and HPLC-RI for glucose, and discussed in terms of selectivity. The results obtained are very promising, as the studied solvents can easily extract phenolic compounds but not glucose, which could improve the subsequent sugar fermentation process. In particular, the bio-based solvent cyclopentyl methyl ether provided extraction efficiencies of phenolic compounds above 93 % while that of glucose remained lower than 4 %. Finally, all the experimental results were analyzed by means of COSMO-RS methodology, obtaining reliable trends and concluding that the ability of the solvents to form hydrogen bonds with phenolic compounds determines the extraction efficiencies.
... ILs can be defined as organic salts in a liquid state with a melting point lower than 373 K [13]. On the other hand, given that the DES field is still in its infancy, a consensus regarding the definition of DESs is yet to be reached [16][17][18][19][20]. According to Martins et al. [20], ''a 'deep eutectic solvent' is a mixture of two or more pure compounds for which the eutectic point temperature is below that of an ideal liquid mixture, presenting significant negative deviations from ideality. ...
... Otherwise, a simpler term 'eutectic solvent' could be used to describe mixtures that do not fulfil these criteria". Therefore, since the definition of these solvents are still being reviewed [16][17][18][19][20], in this work, the term ''eutectic solvent" (ES) was adopted. It should be mentioned that the ESs term suggested by Martins et al. [20] has already been used by several recent papers [17,19,21]. ...
Article
Eutectic solvents (ESs) have been extensively studied in the literature for the purification of fuels. Nevertheless, most studies investigated the extraction of a single type of aromatic from n-alkanes. In this work, aiming to provide insights about the performance of ESs in a process that mimics the multicomponent dearomatization used industrially, a salt-acid-based ES, comprised of methyltriphenyl-phosphonium bromide and acetic acid, was applied in simultaneously extracting toluene, thiophene, quinoline, and pyrrole from n-decane. First, the DES was characterized for its eutectic composition, physicochemical, and critical properties. Then, an initial screening to determine the molecular-level interactions and extraction mechanism were studied experimentally and using COSMO-RS screening charge density profiles and potentials. A physical mechanism was confirmed for the extraction of pyrrole, thiophene, and toluene while for quinoline, an acid-base reaction was the predominant extraction mechanism. The phase diagrams of each impurity were also experimentally determined, predicted using the COSMO-RS model, and correlated using the NRTL model in Aspen Plus. Lastly, a parametric investigation studying the impact of key parameters including stirring time, initial concentration, mixing effects, solvent-to-feed ratio, multi-stage extraction, and repetitive usage of solvent was conducted. On multi-stage extraction, full recovery of pyrrole and quinoline (99.9%) was achieved in only 2-stages, whereas for thiophene and toluene efficiencies of 82.2% and 58.4% were reached after the 5th stage, respectively.
... Polycrystalline films are formed from the perovskite salts by precipitation methods with varying polar solvents. In 2019, Noh et al., tested a perovskite solar cell and attained 23.3% efficiency via an interface passivating method to minimize recombination at the interface [94]. ...
Article
Full-text available
The demand for energy has been a global concern over the years due to the ever increasing population which still generate electricity from non-renewable energy sources. Presently, energy produced worldwide is mostly from fossil fuels, which are non-renewable sources and release harmful by-products that are greenhouses gases. The sun is considered a source of clean, renewable energy, and the most abundant. With silicon being the element most used for the direct conversion of solar energy into electrical energy, solar cells are the technology corresponding to the solution of the problem of energy on our planet. Solar cell fabrication has undergone extensive study over the past several decades and improvement from one generation to another. The first solar cells were studied and grown on silicon wafers, in particular single crystals that formed silicon-based solar cells. With the further development in thin films, dye-sensitized solar cells and organic solar cells have significantly enhanced the efficiency of the cell. The manufacturing cost and efficiency hindered further development of the cell, although consumers still have confidence in the crystalline silicon material, which enjoys a fair share in the market for photovoltaics. This present review work provides niche and prominent features including the benefits and prospects of the first (mono-poly-crystalline silicon), second (amorphous silicon and thin films), and third generation (quantum dots, dye synthesized, polymer, and perovskite) of materials evolution in photovoltaics.
... Additional findings are necessary to fully validate the effectiveness of these solvents as microbial torularhodin extractive agents. In addition, considering the wide range of novel solvents available, the application of computer-aided tools such as COSMObased methods for solvent screening and selection is of great interest to develop sustainable and efficient downstream processes [72,73]. ...
Article
The demand for food, feed, cosmeceutical, and nutraceutical supplements/additives from natural sources has been rapidly increasing, with expectations for a faster expansion than the growth of the global markets in the coming years. In this framework, a particular interest is given to carote-noids due to their outstanding antioxidant activities, particularly the xanthophylls class. Torularhodin is one of these carotenoids that stands out for its multifunctional role as: antioxi-dant, anticancer and antimicrobial, yet its commercial potential is still unexplored. Although most xanthophylls can be naturally found in: microbial, plant and animal sources, torularhodin is only produced by microbial species, especially red oleaginous yeast. The microbial production of xanthophylls has many advantages as compared to other natural sources, such as: the need for low production area, easier extraction, high yields (at optimum operating conditions), and low (or no) seasonal, climatic, and geographic variation dependency. Due to the importance of natural products and their relevance to the market, this review provides a comprehensive overview of the: properties, characteristics and potential health benefits of torularhodin. Moreover, the most promising developments in both upstream and downstream processing to obtain this col-orant from microbial sources are considered. For this purpose, the main microorganisms used for torularhodin production are firstly reviewed, including biosynthesis pathway and torularhodin properties. Following, an overall analysis of the processing aspects related with its: extraction, separation and purification is provided. Lastly, current status and future trends of torularhodin-based processes and products such as therapeutic agents or biomaterials are discussed, indicating promising directions toward biorefinery and circular economy.
... Furthermore, there is considerable research that uses triisooctylamine (Yang et al., 2013), tri-butyl phosphate (Eda et al., 2017), trioctylamine/Octanol and tributyl phosphate (Mukherjee and Munshi, 2020) in the reactive extraction process as effective extractants for a high amount of VFAs recovery. Finally, the extraction process has been amplified by the use of ionic liquids (ILs)-based extractants towards VFAs recovery due to their outstanding separation efficiencies, good stability and, more importantly, well fitted for the environment (Cevasco and Chiappe, 2014;López-Porfiri et al., 2020;Şahin and Kurtulbaş, 2020;Sprakel and Schuur, 2019;Wang et al., 2017). After that, Schuur's group published some potential results of acetic acid recovery by using ionic liquids medium, and they also confirmed that the extraction process is influenced hydrogen bond (Reyhanitash et al., 2019;Reyhanitash et al., 2015;Reyhanitash et al., 2016). ...
Article
Volatile fatty acids (VFAs) are building block chemicals that can be produced through bioconversion of organic waste streams via anaerobic digestion as intermediate products. Purified VFAs are applicable in a wide range of industrial applications such as food, textiles, cosmetics, pharmaceuticals etc. production. The present review focuses on VFAs recovery methods and technologies such as adsorption, distillation, extraction, gas stripping, esterification and membrane based techniques etc., while presenting a discussion of their pros and cons. Moreover, a great attention has been given to the recovery of VFAs through membrane filtration as a promising sustainable clarification, fractionation and concentration approach. In this regard, a thorough overview of factors affecting membrane filtration performance for VFAs recovery has been presented. Filtration techniques such as nanofiltration and reverse osmosis have shown to be capable of recovering over 90% of VFAs content from organic effluent steams, proving the direct effect of membrane materials/surface chemistry, pore size and solution pH in recovery success level. Overall, this review presents a new insight into challenges and potentials of membrane filtration for VFAs recovery based on the effects of factors such as operational parameters, membrane properties and effluent characteristics.
... Solvents, such as ethyl acetate, are the substances used in many industrial processes, including the chemical industry. Due to their wide range of application, world demand for solvents is constantly growing [1][2][3]. Increasingly stringent regulations on emissions of harmful pollutants from production processes make the importance of so called "green chemistry" (non-toxic chemicals to the environment and living organisms) well recognized [4]. There is, therefore, an urgent need for commonly used solvents to have a lower health and environmental impact. ...
Article
Full-text available
The paper presents a study on the performance of a conventional plant-producing ethyl acetate from ethanol and acetic acid. Process models were compiled in the simulator Chemcad 7. The impact of key parameters on the performance of individual installation nodes was examined by sensitivity analysis. Three installation approaches are presented and compared: two classic with different heat duties and an improved one. An improved technological solution, with a closed circulation of the extractant as well as the azeotrope subcooling for better extraction is demonstrated. The energy and mass balance of the installation were developed. The proposed enhancement of a technology with significantly reduced consumption of the fresh extractant also offers a deep recovery of the raw materials, i.e., ethyl acetate and ethanol from wastewater. We assumed that the same energy consumption relative to the classic strategy consumption of ethanol was reduced from 0.531 to 0.524 t/tproduct (−1.2%), fresh process water from 2.18 to 1.42 t/tproduct (−34.9%), and wastewater 2.36 to 1.61 t/tproduct (−31.8%). By this, the wastewater total organic loading (TOL), as well as chemical oxygen demand were nine times reduced. The major advantage is achieved through subcooling of azeotrope, which improves extraction efficiency, making the organic phase enriched with ethyl acetate. Therefore, the performance of the product separation node and the whole system are improved.
... In order to further validate the COSMO-RS predictions, the reliability of H E are contrasted with experimental data [5] and previous PC-SAFT results from our group [78] in Fig. A.14, demonstrating qualitative agreement with the experimental data. In addition, excess entropy, S E , has been used as a valuable parameter to describe the interaction behavior within systems containing DES. [87] A breakdown of the computed energetic contributions for the solvent mixtures studied herein can be found in Fig. A.19, A.20 and A.21. ...
Article
Deep eutectic solvents are mixtures typically composed by a hydrogen bond donor and a hydrogen bond acceptor. They have appeared as an alternative of ionic liquids in several processes due to their tunability, biodegradability and low cost. Recently, deep eutectic solvents have been studied as potential solvents for different applications. Then, their physicochemical properties need to be characterized for understanding the interaction between its constituents and with other compounds. Deep eutectic solvents prepared for this work are based on choline chloride mixed with etóhylene glycol, 1,3-propanediol or 1,4-butanediol at a 1:3 mole ratio. FT-IR spectra was obtained for comparing the different structures of those deep eutectic solvents. Density and viscosity of the prepared deep eutectic solvents were measured from 293.15 K to 333.15 K at 101.13 kPa. Also, the same properties at the same temperature and pressure conditions were obtained for the mixtures of the three deep eutectic solvents with four alcohols: methanol, ethanol, 1-propanol or 1-butanol. Physicochemical (i.e density and excess volume) and transport properties (i.e viscosity) were measured and predicted using PC-SAFT and Free Volume Theory, respectively, for understanding the effect of the temperature variation, the length of the alcohol chain, and length of the hydrogen bond donor on the configurational aspects of the mixture. Subsequently, a prediction of the excess molar enthalpy was performed with COSMO-RS in order to assess the behavior of the same variables on different type of intermolecular interactions from the energetic point of view. The results suggest that mixing each deep eutectic solvent with an alcohol produce negative molar excess volumes and molar excess enthalpies, observing a higher affinity between unlike species.
... Conversely, the definition of DESs has not been refined and finalized as of yet. Attempts with the goal of finding a clear and uniform definition for DESs have been made by several papers 3,15-17 , however, more improvements to the definition are still required [18][19][20][21][22] . According to Martins et al. 22 "a 'deep eutectic solvent' is a mixture of two or more pure compounds for which the eutectic point temperature is below that of an ideal liquid mixture, presenting significant negative deviations from ideality. ...
Article
Full-text available
The interest in green and sustainable solvents has been dramatically increasing in recent years because of the growing awareness of the impact of classical organic solvents on environmental pollution and human health. As a solution to these issues, several greener and more sustainable solvents have been proposed in recent years such as the novel Hydrophobic Eutectic Solvents (HESs). HESs have many advantageous characteristics and could be considered as a potential replacement for both ionic liquids and classical solvents. However, choosing the right HES with the required physiochemical properties for a certain application is an extremely difficult task, especially since large-scale experimental measurements are expensive and time-consuming. Thus, the development of predictive models capable of estimating the properties of these solvents could be considered as a powerful tool in screening new green and sustainable HESs. This work presents two novel Quantitative Structure-Property Relationships (QSPR) models for predicting the density and viscosity of HESs using Conductor-like Screening Model for Real Solvents (COSMO-RS) based descriptors. The data set used includes all the experimental measurements reported in the literature up to the date of writing this work to ensure that the developed models are highly reliable and robust. The results show that the proposed models were excellent at predicting the properties of HES not included in the training set as R2 values of 0.9956 and 0.9871 were obtained for density and viscosity, respectively. This work presents an initiative towards the development of reliable models for predicting the properties of HESs as a means to promote an efficient solvent design approach that can aid in designing and simulating new processes utilizing these novel HESs.
... However, these solvents are characterized as volatile organic compounds (VOCs) that are easily released in the atmosphere and can act as air pollutants promoting the global warming [26,27]. Therefore, there is a growing need to find greener alternatives to reduce the toxic effects on the human health and environmental impact, while improving the efficiency of downstream processes for upgrading food waste materials towards valuable products, including production of natural phenolic antioxidants of commercial value [28][29][30]. This action is framed in the guidelines established by the Twelve Principles of Green Chemistry introduced in 1998 by Paul Anastas and John Warner [31], as well as in the six principles of green extraction of natural producers defined by Chemat et al. [32]. ...
Article
Global food waste is a far-reaching problem, where the recovery of high-value compounds from agri-food effluents using green solvents is an attractive valorisation strategy. Wine industry is an important business sector which generates significant volumes of wastewater, with negative economic and environmental implications. However, winery wastewater can be exploited as a rich source of phenolic antioxidants for food and fine chemical applications. For that purpose, the main goal of this work is the recovery of wine-derived phenolic compounds from liquid effluents using hydrophobic eutectic solvents (HESs). In particular, HESs composed of ammonium salts, DL-menthol and fatty acids, were prepared and evaluated for liquid-liquid extraction of phenolic compounds from synthetic winery wastewater. To achieve optimum extraction performance, the experimental conditions were optimized, including extraction time, solvent to feed volume ratio, dilution factor and type of HESs. The extraction method developed was used for the efficient extraction of natural antioxidants from wine-derived samples and gallic acid from aqueous solutions. The extracted phenolic compounds were quantified and determined by spectrophotometric methods and high-performance liquid chromatography (HPLC). The experimental results showed satisfactory recoveries of the target compounds within the range of 64.14-84.10% from winery wastewater and recoveries between 74.86-92.31% from gallic acid solutions. Chloride ammonium salts-based HESs, especially N8881Cl-DL-Menthol and N8881Cl-Octanoic acid, proved the highest potential for phenolic compounds recovery from winery wastewater matrices and aqueous solutions. Finally, the antioxidant capacity of the extracts was confirmed.
Article
The solubility and involved energies of organic acids in green solvents are relevant to the design of sustainable biorefinery downstream processes. In this work, the solubility of two important bio-based organic acids such as succinic acid and fumaric acid, in water and four bio-based solvents (i.e., ethyl acetate, 1,8-cineole, cyclopentyl methyl ether, and 2-methyl tetrahydrofuran) were measured within a temperature range of [283 – 313] K. A gravimetric methodology was adopted, previously validated using the organic acid aqueous solubilities available in the literature. The reported data present an average estimated uncertainty of measurement, with a level of confidence of 95%, of 5.2·10⁻⁴ mol·mol⁻¹. Experimental results were correlated with the van’t Hoff equation, and the Buchowski–Ksiazaczak λh model, where the root mean squared deviations were less than 3.9·10⁻⁴ for all systems. From the experimental data and the COSMO-RS molecular simulation method, the solid-liquid equilibria were modelled to estimate the excess energies and the solute activity coefficients of the saturated solutions. Excess enthalpy contribution analysis shows that attractive hydrogen-bonding interactions between the organic acids and the green solvents drive the dissolution phenomena. The magnitude of the hydrogen-bonding interactions increases with temperature for all systems, agreeing with the observed solubility trends. The organic acid energies of solution were estimated from the van’t Hoff equation, demonstrating an enthalpy-entropy compensation effect. The energetic analysis shows that the dissolution phenomenon is an enthalpy-driven process for fumaric acid, whereas no predominant effect is observed for succinic acid.
Article
Common separation materials are divided into two-dimensional (2D) materials and three-dimensional (3D) materials, among which three-dimensional materials have excellent durability and stability. Herein, we developed a durable [email protected]@PU sponge by simply immersing polyurethane (PU) sponges in a blending solution of starch granules and polydimethylsiloxane (PDMS). Blending starch granules and PDMS could achieve more reliable adhesion of starch granules to the PU sponge by utilizing the high adhesion of PDMS. At the same time, the presence of starch granules could make PDMS form a spot-like secondary structure on the sponge. The sponge exhibited excellent hydrophobicity and high organic solvent affinity, and could separate and absorb organic solvents from the turbulent flow. The results showed that the sponge could absorb and hold 46 times its organic solvent weight, with a separation efficiency greater than 98.5% for different organic solvents. In addition, the sponge maintained a water contact angle of more than 140° after 40 abrasion cycles or after immersion in different pH and salt solutions for 48 h, showing excellent mechanical durability and chemical stability.
Chapter
Lignocellulosic material is an inexpensive feedstock considered a sustainable and renewable option to replace a wide range of fossil‐based products through the bioconversion of this renewable material into biofuels and value‐added products. Lignocellulosic biomass is the main structural component of woody and non‐woody plants and makes up most of the cellulose, hemicellulose, and lignin. The effective use of the three main components will play a significant role in the economic viability of biochemicals. The biomass conversion process involves four main steps: choosing the effective pretreatment, production of saccharolytic enzymes cellulases and hemicellulases, fermentation of hexoses and pentoses, and downstream processing. In the context of the production of chemical products from biomass, pretreatment provides an increase of the accessibility of the biomass components making them susceptible to the action of different hydrolytic enzymes. It is believed that the limited effectiveness of most enzymatic processes in lignocellulosic biomass is due to possible difficulties related to the pretreatment of raw materials. This chapter proposes an overview of the advance in chemical pretreatments and the current global scenario from the biorefinery concept to the platform of chemicals and other value‐added bioproducts.
Article
Citric acid is one of widely used acids in industry and its recovery from waste streams is critical. Emulsion liquid membrane is one of the most effective recovery methods, which has been investigated in recent years. Numerous transport phenomena parameters affect the efficiency of this process. From the process equipment design point of view, optimization based on overall cost is of great importance and important equipment sizing decisions/constraints must be considered. A physics‐based model for a full‐scale simulation of emulsion liquid membrane systems is very useful. This work is focused on developing and verifying such a model. A coupled particle/mixture simulation was carried out in this work and the modeling results were fitted on the experimental data. The novelty of this modeling work is physics‐based results based on the system's geometry and its effects on the mass transfer resistances. Since the model is physics‐based, the model is capable of simulating similar systems with any geometry or experimental conditions. This article is protected by copyright. All rights reserved.
Chapter
Solvent extraction plays a crucial role in biorefinery processes, such as the extraction of lipids from algae biomass to produce biodiesel. Volatile organic solvents, such as hexane, are typically used to extract algae lipids, but this involves high energy consumption for solvent recovery and negative environmental impacts due to its hazardous, volatile, and flammable nature. This study proposes a systematic methodology combining molecular simulation techniques, data classification methods, and process simulation to screen solvents for lipid extraction from wet algae biomass. The novelty relies on the integration of techno-economic, environmental and safety criteria, such that all three sustainability dimensions are considered in solvent selection. First, thermodynamic equilibrium data of solvent-lipid systems are predicted with the COSMO-RS method. Then, a clustering method (K-means algorithm) is used to identify and select the solvents with the highest partition coefficient and selectivity towards lipids. After this, the selected solvents are further screened considering their physicochemical properties (solubility in water, density, viscosity, boiling point) and health, safety, and environmental performance. Finally, the lipid extraction process with the shortlisted solvents is simulated in Aspen Plus to obtain techno-economic and environmental sustainability performance indicators. Out of 88 initial solvent candidates, limonene and ethyl tert-butyl ether are identified as promising alternatives to the benchmark solvent (hexane), as they are non-hazardous and have higher selectivity towards lipids. However, their use involves higher energy requirements, operating costs, and greenhouse gas emissions in the lipid extraction process. This methodology can be applied to other extraction processes to find sustainable alternatives for the conventional solvents and identify trade-offs from a techno-economic and environmental perspective at the early stages of process design.
Article
Supported liquid membranes (SLMs) containing novel green solvents are proposed as a sustainable alternative separation process in the recovery of biomolecules. In this work, succinic acid has been successfully extracted from model fermentation broths through a stripping phase-facilitated transport mechanism with four different green supported liquid membranes: two eutectic solvents (DL-menthol:OctA and N4444Cl:OctA), the bio-based solvent eucalyptol and the ionic liquid [C4pyrr][Tf2N]. A permeability activity-based model that takes into account for the first time solute-phase affinities has been developed using the quantum chemical COSMO-RS method; the model corrects the mass transfer driving force and allows extraction predictions beyond the concentration equilibrium. The best recovery has been achieved experimentally for the eucalyptol-based SLM (concentration factor of 1.4) using an alkaline aqueous solution (0.5M NaOH) as the stripping phase. A countercurrent cascade extraction process design is proposed, and a graphical method to determine the stage number, interstage concentrations as well as mass transfer area requirements is presented. This new tool, the Permeability Activity-Based Linear Operation (PABLO) method, will substantially enhance the process design of SLMs technology for the biorefinery industry.
Chapter
This chapter gives a comprehensive overview of the liquid membrane (LM) technology applied for sustainable separations. The basic concepts and definitions of LMs are presented, along with a selection of the most relevant applications for the development of sustainable processes. Fundamental aspects inherent to the liquid membrane operation are given as well to help the reader understand the scope of the technology and its current limitations. LMs are classified into three main configurations: bulk liquid membrane, emulsion liquid membrane, and supported liquid membrane. A range of mathematical transport models for LMs can be found in the literature. Although the derivation of transport models depends strongly on the specific system constituents and LM configuration, i.e. physical phases and contactor arrangement, the solute‐diffusion approach is their common starting point. LM technology has proved to be a sustainable separation method at a laboratory scale, which could potentially replace commercial LLX systems for several applications.
Article
Full-text available
The increasing discharge of metal-associated waste not only causes growing concerns on the environment and human health but also accelerates the depletion of natural metal resources. Within this context and...
Article
The presence of bioactive compounds in winery waste streams represents a great opportunity to revalue these effluents that constitute a challenging environmental and economic problem. The main objective of this research is to develop an efficient and environmentally friendly liquid-liquid extraction process for the recovery of phenolic antioxidants from winery wastewater. Two bio-based solvents, 2-methyltetrahydrofuran (2-MeTHF) and cyclopentyl methyl ether (CPME), were evaluated as potential extractants along with ethyl acetate (EA) as benchmark organic solvent. Extraction efficiencies were maximized by testing several operation factors such as stirring time, solvent to feed ratio, concentration and alcohol effect. Subsequently, the extracted phenolic compounds were quantified by spectrophotometric (using the Folin-Ciocalteu assay, the flavonoid-aluminum chloride complexation assay and the DPPH free radical assay) and chromatographic (HPLC-DAD) methods. Overall, 2-MeTHF showed the highest extraction efficiency of target antioxidants, yielding up to 96.46% for gallic acid, 87.44% for protocatechuic acid, 80.82% for 4-hydroxybenzoic acid, 92.24% for caffeic acid, 75.18% for vanillic acid and 38.19% for syringic acid. In the interest of full sustainability, the isolation of the phenolic compounds as a solid fraction from the extraction solvent was efficiently accomplished, while the recyclability of 2-MeTHF was successfully demonstrated.
Article
Full-text available
Solvents are important in most industrial and domestic applications. The impact of solvent losses and emissions drives efforts to minimise them or to avoid them completely. Since the 1990s, this has become a major focus of green chemistry, giving rise to the idea of the 'green' solvent. This concept has generated a substantial chemical literature and has led to the development of so-called neoteric solvents. A critical overview of published material establishes that few new materials have yet found widespread use as solvents. The search for less-impacting solvents is inefficient if carried out without due regard, even at the research stage, to the particular circumstances under which solvents are to be used on the industrial scale. Wider sustainability questions, particularly the use of non-fossil sources of organic carbon in solvent manufacture, are more important than intrinsic 'greenness'. While solvency is universal, a universal solvent, an alkahest, is an unattainable ideal. Supplementary information: The online version contains supplementary material available at 10.1007/s10098-021-02188-8.
Article
In the current context of a growing demand for environmentally friendly technologies, this study aims to evaluate and develop an efficient liquid-liquid extraction procedure of phenolic acid antioxidants from aqueous environments using bio-based solvents. Due to their abundance in industrial effluents and their importance for human health, a better understanding of how the molecular structures of phenolic antioxidants impact their recovery for pharmaceutical and fine chemical applications is required. Following the principles established by Green Chemistry, the use of eco-friendly solvents including 2-methyltetrahydrofuran (2-MeTHF), cyclopentyl methyl ether (CPME) and D-limonene (LIM) was evaluated in comparison with the conventional organic solvent, ethyl acetate (EA), for liquid-liquid extraction of nine representative phenolic acids: five hydroxybenzoic acids and four hydroxycinnamic acids. The distribution of the target compounds in each phase after the extraction process was obtained by UV-Visible spectrophotometry. The highest extraction yields, up to 100 %, were obtained with 2-MeTHF, followed by the conventional solvent EA and by CPME. On the contrary, LIM showed the lowest extraction efficiencies. The effect of the molecular structures of the compounds involved in the extraction process was analysed. In addition, the recyclability of 2-MeTHF in consecutive extraction cycles was demonstrated. Overall, a simple and more environmentally friendly liquid-liquid extraction process was developed for the recovery of hydroxybenzoic and hydroxycinnamic acids, while providing insights into the behaviour of the extraction process of phenolic acids using more sustainable solvents
Article
Various eutectic systems have been proposed and studied over the past few decades. Most of the studies have focused on three typical types of eutectics: eutectic metals, eutectic salts, and deep eutectic solvents. On the one hand, they are all eutectic systems, and their eutectic principle is the same. On the other hand, they are representative of metals, inorganic salts, and organic substances, respectively. They have applications in almost all fields related to chemistry. Their different but overlapping applications stem from their very different properties. In addition, the proposal of new eutectic systems has greatly boosted the development of cross-field research involving chemistry, materials, engineering, and energy. The goal of this review is to provide a comprehensive overview of these typical eutectics and describe task-specific strategies to address growing demands.
Article
Deep eutectic solvents based on cineole as hydrogen bond acceptors and organic acids (succinic, malic, and lactic) as hydrogen bond donors are studied using a theoretical approach. The nature, strength, and extension of hydrogen bonding are analyzed, thus quantifying this prevailing interaction and its role in the fluid properties. Density functional theory was used to study small molecular clusters, and the topological characterization of the intermolecular forces was carried out using atoms in a molecule theory. Classical molecular dynamics simulations were considered to study nanoscopic bulk liquid properties and their relationship with relevant macroscopic properties such as density or thermal expansion. The reported results provide the characterization of environmentally friendly deep eutectic solvents and show the suitability of cineole for developing these sustainable materials.
Article
Here, we demonstrate the use of Raman spectroscopy for real-time monitoring and analysis of the reduction of nitroarenes and ketones in an aqueous medium using an external fiber optic probe. In one case, the catalytic reduction of nitroarenes using hydrazine hydrate and a nickel boron composite catalyst was studied by monitoring the disappearance of the distinct nitro stretching frequency at 1350 cm-1. Quantitative Raman spectroscopic techniques showed that the aqueous reduction reaction proceeds with pseudo-first-order kinetics. The biphasic reduction of cyclic ketones by aqueous dimethylamine borane (DMAB) was also examined. A nonpolar carbonyl compound and aqueous DMAB were mixed and an external Raman probe monitored the loss of the starting material via the carbonyl stretch at 1713 cm-1 in the top organic phase. We also found that saturated aliphatic carbonyl compounds were reduced much faster than α,β-unsaturated and aromatic carbonyl compounds. Additionally, DMAB was found to be unreactive toward epoxides and esters, allowing for selective reduction of aliphatic ketones. Density functional theory analysis suggests that carbonyl reduction occurred through a dissociation mechanism followed by a concerted hydride transfer pathway.
Article
The most important developments in solvent-based fluid separations, separations involving at least one fluid phase, are reviewed. After a brief introduction and discussion on general solvent trends observed in all fields of application, several specific fields are discussed. Important solvent trends include replacement of traditional molecular solvents by ionic liquids and deep eutectic solvents and, more recently, increasing discussion around bio-based solvents in some application fields. Furthermore, stimuli-responsive systems are discussed; the most significant developments in this field are seen for CO 2 -switchable and redox-responsive solvents. Discussed fields of application include hydrocarbons separations, carbon capture, biorefineries, and metals separations. For all but the hydrocarbons separations, newly reported electrochemically mediated separations seem to offer exciting new windows of opportunities. Expected final online publication date for the Annual Review of Chemical and Biomolecular Engineering, Volume 12 is June 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
Article
Liquid–liquid equilibrium data on butyric acid (BA) extraction by new ionic liquid (IL) tetradecyl(trihexyl)phosphonium neodecanoate ([C14C6C6C6P][NDec]) are presented and correlated using a model developed earlier. Extraction performance of the new IL is comparable with that of previously tested phosphonium ILs with decanoate and phosphinate anions. High loading of IL with BA of more than 12 BA molecules per one IL ion pair was achieved at aqueous BA concentration of 1.2 mol dm−3. The overall extraction mechanism includes competitive extraction of BA and water, and coextraction of BA with water. Both these sub-mechanisms act simultaneously, the first one dominates below IL loading by acid of 2 and the second one above this value. Dynamic viscosity of water saturated [C14C6C6C6P][NDec] is slightly higher compared to a similar IL with decanoate anion [C14C6C6C6P][Dec] (104 and 96 mPa s). However, at 298 K dried [C14C6C6C6P][Dec] is solid, while [C14C6C6C6P][NDec] is liquid even below 253 K which is a great advantage. Viscosity of equilibrium organic phases shows a maximum at IL loading by BA of about 1.6 which corresponds to the minimal solute (BA + water) content and maximal molar fraction of IL due to water release from the solvent.
Article
The growing demand for high added-value products, such as vanilla-derived compounds, and increasing environmental regulations make evident the need to find new sustainable solvents for extraction processes, which meet both legislative requirements and expected yields. Vanilla-derived compounds are known for their antioxidant and beneficial properties for human health. These compounds can be recovered from effluent streams, promoting decontamination and revaluation of wastewater. The potential of using neoteric solvents, i.e., biobased solvents and hydrophobic eutectic solvents, as an alternative to conventional volatile organic solvents, such as ethyl acetate, for sustainable recovery of vanilla-derived compounds through liquid-liquid extraction from aqueous environments was investigated. Three biobased solvents (2-methyltetrahydrofuran, cyclopentyl methyl ether, and d-limonene) and three hydrophobic eutectic solvents constituted by menthol and organic acids (1:1 dl-menthol:octanoic acid, 1:1 dl-menthol:decanoic acid, and 2:1 dl-menthol:dodecanoic acid) were evaluated. The extraction process was optimized in terms of the stirring time and solvent:feed volume ratio. The effect of the initial solute concentration was also analyzed. The extraction efficiency of solvents was determined by UV-visible spectrophotometry and high-performance liquid chromatography with diode-array detection. The experimental results indicated that 2-methyltetrahydrofuran yielded the highest extraction efficiency from a vanilla bean extract solution for both vanillin (95.37%) and vanillic acid (91.96%) with good repeatability (RSD < 0.40%). Regarding the rest of the neoteric solvents, cyclopentyl methyl ether and hydrophobic eutectic solvents provided extraction values between 31.6 and 95.4% for both vanilla-derived compounds, while d-limonene was significantly less effective. Finally, a solvent recycling and reuse study was successfully carried out, showing that 2-methyltetrahydrofuran stands out as a promising biobased extraction solvent for sustainable recovery of valuable vanilla constituents.
Article
Solvents play a primary role in the chemical industry, with an increasing regulatory pressure urging to find more benign replacements for conventional fossil-derived solvents. Considering the wide variety of green solvent alternatives, efficient methods for rational screening are key to promote sustainable processes based on neoteric solvents. This paper summarizes recent advances on green solvent screening using computer-aided methods, focused on macroscale modelling of phase equilibrium properties. Particular attention is paid to quantum chemistry methods based on Conductor-like Screening MOdel (COSMO) as a tool for guiding solvent selection from thermodynamic performance indicators. Integrated methods based on COSMO-derived molecular descriptors combined with molecular and large data-based methods are revised as significant approaches for multi-objective problems. Relevant solvent screening applications for separation operations, reactive systems, and environmental and health properties estimation are reviewed. Future prospects for the design of sustainable industrial systems based on green solvents using in silico strategies are discussed.
Article
Chlorinated solvents were once, and in many places are still, ubiquitous in chemistry laboratories. This review explores the properties that led to such widespread use, why there is now an increasing drive to minimize usage, and what alternatives are currently available.
Article
In this work, a molecularly imprinted polymers (MIPs)-based SERS sensor for selective, sensitive, quantitative and recyclable detection of paclobutrazol residue in complex environments has been proposed. In this strategy, [email protected]@Ag (FSAA) nanocomposites with tunable [email protected] interparticle gaps are constructed. Then by tuning the [email protected] nanogaps and investigating the SERS enhancement mechanism of FSAA, we achieve the optimal SERS substrates, FSAA-40. After combination with MIPs, we can selectively detect the paclobutrazol in soil with a detection limit of 0.075 µg/g. When the paclobutrazol concentration ranges from 0.075 to 12.75µg/g, the SERS intensity shows linear correlation, which opens the possibility in quantitative detection. Our magnetic MIPs-based SERS sensor can be easily separated, efficiently recycled, and expanded to more universal environments, which demonstrates promising future in food and environmental safety.
Article
The loss and waste of food is a matter of great concern, leading to a multifaceted problem with negative economic, social, and environmental impacts as addressed in the UN Sustainable Development Goals number 2: zero hunger. The wine, fruit juice and vegetable oil processing industries generate significant amounts of wastes and side streams containing potentially valuable bioactive compounds. Some of them are plant secondary phenolic metabolites that offer remarkable health benefits (as antioxidants and anti-inflammatory compounds). One of the current challenges is the recovery of such bioactive compounds from residual matrices for further applications in food, pharmaceutical and cosmetic industries. Within this framework and in the scope of the Green Chemistry concept, one of the current challenges is to find eco-efficient techniques for the recovery of bioactive compounds. In this context, neoteric solvents are considered a greener alternative to traditional solvents, as the latter are more harmful to human and animal health, and environment. This overview focuses on recent advances in the use of hydrophobic neoteric solvents, i.e. ionic liquids, eutectic solvents, and bio-based solvents, for liquid-liquid extraction of phenolic compounds from liquid agri-food matrices.
Article
Full-text available
A wide overview of the biphasic production of 5-hydroxymethylfurfural and furfural from lignocellulosic sugars is presented together with a screening of solvents following a methodology based on COSMO-RS and section guides.
Article
Full-text available
Green chemistry has seen significant growth, driven by cost savings, regulation, and customer demand. At the same time, this growth has been slow and uneven. While large companies in developed markets have for the most part implemented GC strategies, this is not the case for smaller companies and manufacturers in developing countries such as China and India. Many of the barriers reported earlier remain today and include lack of policy incentives, insufficient funding and expertise in GC, lack of green solutions for some processes, and lack of effective metrics to track GC impacts. Advancing global adoption of GC along the entire supply chain requires more radical actions including smarter and globally coordinated regulations, restructuring of current markets, supporting greater consumer awareness and demand for green products, investment in GC training and application, and a means to assess the global impact of GC implementation on environmental performance over time.
Article
Full-text available
Production of volatile fatty acids (VFAs) by fermentation is a potential sustainable alternative for conventional petrochemical routes to VFAs. Due to the low VFA content of fermentation broths, robust and economical separation technology has to be devised to recover the VFA. Liquid-liquid extraction of VFAs with the phosphonium phosphinate ionic liquid (IL) [P666,14][Phos] allows good VFA extractability. For an extraction process using [P666,14][Phos] to be green, it is essential to efficiently regenerate the solvent and recover the VFA. To obtain insight in the (strong) intermolecular interactions between [P666,14][Phos] and, acetic acid, selected as model VFA, 1H NMR, 31P NMR, FT-IR and isothermal titration calorimetry (ITC) were applied. The observations were used to interpret operations to recover acetic acid from the IL, which included evaporation at elevated temperature under vacuum, possibly assisted by nitrogen stripping, in situ esterification and back-extraction with volatile bases. Through evaporative regeneration with nitrogen stripping, HAc could be removed, but only down to an HAc/IL molar ratio of 1. The remaining molar equivalent of HAc-IL interacts tightly with the IL by partial proton transfer and strong hydrogen bonding interactions with the phosphinate anion. Back-extraction of HAc with trimethylamine (TMA) and subsequent decomposition of the HAc-TMA complexes allowed for successful IL regeneration. This process uses ten times less amine (TMA) than conventional amine-based extraction processes (e.g. tri-n-octyl amine), and provides a sustainable process route to obtain pure carboxylic acids from highly diluted aqueous solutions without generating large streams of byproducts. Further valorization via in-line vaporization/catalytic ketonization or via in-line thermal decomposition and ketonization of the TMA-HAc salt was also demonstrated, showing the potential of the VFAs as green platform for bio-based chemicals.
Article
Full-text available
The growing desire to produce organic acids through fermentative routes, as a starting point for bio-based plastics, has revived the scientific attention on carboxylic acid removal from aqueous streams. One of the main technologies to recover carboxylic acids from diluted aqueous streams is liquid-liquid extraction (LLX). In this review, solvent developments for LLX of carboxylic acids are reviewed. In the past decades, a significant number of research papers have appeared, describing completely new solvents such as ionic liquids, as well as improvements of the traditional state-of-the-art solvent systems comprising of amines and organophosphorous extractants in diluents. The state-of-the-art technology for acid extractions has long been using trioctylamine (TOA) — or Alamine 336, a commercial mixture of trialkyl amines — as the complexating agent. However, with dropping acid concentrations, the economic feasibility of the TOA-based processes is compromised. This review discusses three main categories of solvents, i.e. composite solvents containing nitrogen-based extractants, phosphorous-based extractants and ionic liquids, and includes a discussion on solvent property models that may aid solvent selection. Furthermore, regeneration strategies are discussed, aiming to provide direction towards regenerations that do not further dilute streams that are already diluted before the LLX process. The main conclusion with respect to solvent regeneration when back-extraction is applied, is that solvent-swing strategies should be applied that maximize the ratio between the acid distribution coefficient in the forward extraction and the distribution coefficient in the back-extraction at minimal energy cost. This appears to be through evaporation of part of the diluent after the primary extraction.
Article
Full-text available
The screening of natural deep eutectic solvents (NADES) to identify those with the ability to strongly solvate rutin was conducted using the COSMO-RS methodology. A NADES model was constructed that took into account the possible ionic and neutral forms of its constituents. The distributions of all forms were computed based on the equilibrium constants of neutralization reactions between amino and carboxylic acids. The proposed model was validated against the experimental solubilities of 15 NADES. A linear relationship between these data and the estimated activity coefficient values was found. The screening encompassed 126 different NADES. It was found that ten of them outperformed the best reference system. The most effective two-component solvent comprised proline combined with 2,3-diaminosuccinic acid, and the solubility of rutin in this solvent was found to be 130% greater than its solubility in the best reference system. The amino acids associated with the highest rutin solubilities were all cyclic, and the use of carboxylic acids with two carboxyl groups and a main chain consisting of two methylene groups with two amino substituents was observed to yield the best rutin solubilities. Because of the acidic properties of rutin, the presence of basic sites on the components of the NADES generally leads to enhanced solubility. Electronic supplementary material The online version of this article (10.1007/s00894-018-3700-1) contains supplementary material, which is available to authorized users.
Article
Full-text available
Succinic acid is a four-carbon dicarboxylic acid, which has attracted much interest due to its abroad usage as a precursor of many industrially important chemicals in the food, chemicals, and pharmaceutical industries. Facing the shortage of crude oil supply and demand of sustainable development, biological production of succinic acid from renewable resources has become a topic of worldwide interest. In recent decades, robust producing strain selection, metabolic engineering of model strains, and process optimization for succinic acid production have been developed. This review provides an overview of succinic acid producers and cultivation technology, highlight some of the successful metabolic engineering approaches.
Article
Full-text available
Levulinic acid (LA) can be produced from lignocellulosic materials via hydroxylation followed by an acid-catalyzed conversion of hexoses. Inorganic homogeneous catalysts are mostly used, in particular sulphuric acid, yielding a mixture of LA with sulphuric acid, formic acid (FA) and furfural. Significant attention has been paid to optimization of the yield, but purification of the LA is a challenge too. This work focuses on the separation of LA from the complex aqueous mixtures by liquid-liquid extraction. Two aqueous product feeds were considered, reflecting two different processes. One aqueous product stream contains sulphuric acid and LA, while the second product stream also contains formic FA and furfural. Furfural could be removed selectively via liquid-liquid extraction with toluene. For selective extraction of LA and FA without co-extracting sulphuric acid, 30 wt.% of trioctylphosphine oxide (TOPO) in methylisobutylketone (MIBK) was found most suitable, showing a high selectivity over sulphuric acid, and a high equilibrium partitioning of LA. When instead of MIBK, 1-octanol was applied as diluent, the co-extraction of FA was enhanced, while hexanoic acid suppressed the acid extraction. To obtain the LA pure, eventually a distillation is required, and the potential of temperature swing back extraction (TSBE) at 90°C to pre-concentrate the acid solutions was evaluated for 30 wt.% TOPO in MIBK. This pre-concentration step increased the concentrations of LA and FA by a factor of 2.45 and 2.45 respectively, reducing the distillation reboiler duty from roughly 31.5 to 11.3 GJ per ton LA, at a cost of roughly 4.5 GJ heating duty per ton produced LA.
Article
Full-text available
Hydrophobic deep eutectic solvents (DESs) are presented for the first time. They consist of decanoic acid and various quaternary ammonium salts. The effect of the alkyl chains on the hydrophobicity and the equilibrium of the two-phase DES–water system were investigated. These new DESs were successfully evaluated for the recovery of volatile fatty acids from diluted aqueous solutions.
Article
Full-text available
The research into ionic liquids (IL) has escalated in the last two decades, ever since the potential for new chemical technologies was realized. In the period covered by this review, approximately 6000 journal articles have been published on the topic. Compared to classical ILs, the research into DESs is comparatively in its infancy, with the first paper on the subject only published in 2001. DESs contain large, nonsymmetric ions that have low lattice energy and hence low melting points. They are usually obtained by the complexation of a quaternary ammonium salt with a metal salt or hydrogen bond donor (HBD). A majority of ionic liquids which are fluid at ambient temperatures are formed using an organic cation, generally based around ammonium, phosphonium, and sulfonium moieties. The second generation of ionic liquids are those that are entirely composed of discrete ions, rather than the eutectic mixture of complex ions seen in the first generation ionic liquids.
Article
Full-text available
In its first applications to ionic liquids the COSMO-RS method has shown to yield good qualitative and satisfying quantitative predictions for the activity coefficients of neutral compounds in ionic liquids and for binary mixtures of ionic liquids and neutral solvents. Since this success was achieved predictively, i.e. without any special parameterization, COSMO-RS since then has become a widely used and efficient tool for the prediction and screening of ionic liquid properties. In this article we give an overview of the various approaches and methodological differences used in this context by different groups.
Article
Full-text available
A series of hydrophilic and hydrophobic 1-alkyl-3-methylimidazolium room temperature ionic liquids (RTILs) have been prepared and characterized to determine how water content, density, viscosity, surface tension, melting point, and thermal stability are affected by changes in alkyl chain length and anion. In the series of RTILs studied here, the choice of anion determines water miscibility and has the most dramatic effect on the properties. Hydrophilic anions (e.g., chloride and iodide) produce ionic liquids that are miscible in any proportion with water but, upon the removal of some water from the solution, illustrate how sensitive the physical properties are to a change in water content. In comparison, for ionic liquids containing more hydrophobic anions (e.g., PF6− and N(SO2CF3)2−), the removal of water has a smaller affect on the resulting properties. For a series of 1-alkyl-3-methylimidazolium cations, increasing the alkyl chain length from butyl to hexyl to octyl increases the hydrophobicity and the viscosities of the ionic liquids increase, whereas densities and surface tension values decrease. Thermal analyses indicate high temperatures are attainable prior to decomposition and DSC studies reveal a glass transition for several samples. ILs incorporating PF6− have been used in liquid/liquid partitioning of organic molecules from water and the results for two of these are also discussed here. On a cautionary note, the chemistry of the individual cations and anions of the ILs should not be overlooked as, in the case of certain conditions for PF6− ILs, contact with an aqueous phase may result in slow hydrolysis of the PF6− with the concomitant release of HF and other species.
Article
Full-text available
This report identifies twelve building block chemicals that can be produced from sugars via biological or chemical conversions. The twelve building blocks can be subsequently converted to a number of high-value bio-based chemicals or materials. Building block chemicals, as considered for this analysis, are molecules with multiple functional groups that possess the potential to be transformed into new families of useful molecules. The twelve sugar-based building blocks are 1,4-diacids (succinic, fumaric and malic), 2,5-furan dicarboxylic acid, 3-hydroxy propionic acid, aspartic acid, glucaric acid, glutamic acid, itaconic acid, levulinic acid, 3-hydroxybutyrolactone, glycerol, sorbitol, and xylitol/arabinitol. In addition to building blocks, the report outlines the central technical barriers that are preventing the widespread use of biomass for products and chemicals.
Article
Full-text available
COSMO-RS, a general and fast methodology for the a priori prediction of thermophysical data of liquids is presented. It is based on cheap unimolecular quantum chemical calculations, which, combined with exact statistical thermodynamics, provide the information necessary for the evaluation of molecular interactions in liquids. COSMO-RS is an alternative to structure interpolating group contribution methods. The method is independent of experimental data and generally applicable. A methodological comparison with group contribution methods is given. The applicability of the COSMO-RS method to the goal of solvent screening is demonstrated at various examples of vapor–liquid-, liquid–liquid-, solid–liquid-equilibria and vapor-pressure predictions.
Chapter
Biomolecule separation is critical to the field of biotechnology. Biomolecules include a broad diversity of primary and secondary metabolites with distinct structures and functionalities that provide an excellent platform for production of pharmaceuticals, fine chemicals, food additives, cosmetics, and advanced materials. However, efficient isolation and purification of biomolecules from natural matrices and fermentation broths represent the bottleneck of the downstream production process. Common methods involve solvent-based extractions, including conventional liquid–liquid or solid–liquid extraction and more advanced microwave- and ultrasound-assisted extraction. In this context, solvent selection remains the key factor in developing cost-effective and environmentally friendly separation processes for biomolecule recovery. Traditionally, extraction techniques rely on harmful volatile organic compound solvents subject to increasing regulations in the chemical, food, and consumer goods industries. Recently, neoteric solvents with improved environmental, health, and safety profile have emerged as promising alternatives for sustainable processing in biotechnological applications. This chapter provides a critical overview of recent advances and future trends in green solvents for bioseparations, focusing on ionic liquids, deep eutectic solvents, and biobased solvents for extraction of representative biomolecules. Furthermore, modern solvent selection tools will be reviewed to provide a comprehensive framework toward designing the next generation of sustainable bioseparation processes.
Article
Current liquid-liquid extraction techniques for fractionation of essential oils rely on hazardous volatile organic compounds to concentrate target solutes for further food, fine chemical and medical applications. Herein, bio-renewable deep eutectic solvents based on various alkanediols were assessed as environmentally friendly alternatives to separate bioactive terpenoids from terpenes for essential oil downstream processing. In particular, DES composed of choline chloride as hydrogen bond acceptor and alkanediols including 1,3-butanediol, 2,3-butanediol, 1,2-propanediol or 1,3-propanediol as hydrogen bond donors at 1:2 ratio were used for fractionation of citrus essential oil model mixtures and real crude orange essential oil at mild conditions. The effect of the structure of alkanediols (i.e. length of hydrocarbon chain and the position of hydroxyl group) on the essential oil extraction performance provided by the different DES was explored in terms of experimental liquid-liquid equilibrium, distribution coefficients and selectivities. Additionally, the experimentally measured thermodynamic parameters were compared against those estimated using COnductor-like Screening MOdel for Real Solvents as a tool for solvent selection. Lastly, a further thermodynamic understanding of the behavior of the systems was performed by analysis of the computed sigma profiles, activity coefficients, excess enthalpies and molecular interactions between the terpenic hydrocarbon solutes and the solvents. Overall, the proposed alkanediol-based DES are feasible solvents for essential oil fractionation, arising as promising candidates to develop sustainable essential oil purification processes through selective isolation of terpenoid compounds.
Article
Isothermal Titration Calorimetry (ITC) and molecular modeling (MM) were combined with liquid-liquid equilibrium data to obtain better understanding of solvent effects on complexation in reactive liquid–liquid extraction. Two examples with ample extraction literature available were studied, acetic acid extraction and phenol extraction. Interactions with binary solvents were studied. Based on the insight and quantification of complexation with MM and ITC, models describing the liquid-liquid equilibrium (LLE) were formulated and validated with experiments, showing that ITC can predict LLE. ITC together with MM indeed can yield additional insight in complexation behavior in reactive liquid–liquid extraction and may guide solvent selection procedures. © 2018 The Korean Society of Industrial and Engineering Chemistry
Article
The main goal of this work is to compare the ability of aromatic and non-aromatic ionic liquids (ILs) as potential solvents to extract phenolic compounds from aqueous systems. Although these liquid salts have been widely studied in the separation of organic compounds, especially aromatic hydrocarbons such as benzene, toluene, ethylbenzene, and isomer xylenes, their application to separate phenols from wastewater is still much less widespread. For that reason, in this work, the extraction efficiency of phenolic compounds in molecular form (phenol, o-cresol, and resorcinol) from water using non-aromatic (1-hexyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide, [HMpyr][NTf2]) and aromatic (1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [HMim][NTf2]) ILs was analyzed and discussed. Firstly, the optimal operating conditions (stirring and settling time, and phase volume ratio Vionic liquid/Vwater) were stablished and then other variables such as initial phenol concentration and temperature were also studied. This work was performed through equilibrium distribution studies and the tracking of the concentration of phenol was carried out by absorbance measurements using a UV/visible spectrophotometer. In order to provide a better understanding of the effect of the cation nature (aromatic and non-aromatic) as well as the role of the phenolic structure on the extraction ability of the ILs, the quantum chemical COSMO –RS method was used to seek an explanation in terms of molecular interactions between the solvents and the phenolic compounds. Overall results support that the aromatic nature of cations does not seem to be the predominant factor driving the extraction process, with hydrogen bonding significantly contributing to competitive solute-solvent interactions which promote the transfer of the phenolic compounds from the aqueous phase to the IL phase.
Article
Citrus essential oils are complex hydrocarbon mixtures mainly composed of terpenes and terpenoids and are widely used as raw materials in food, pharmaceutical, and fine chemical industries. However, essential oil deterpenation (i.e., separation of terpenes and terpenoids) is required to preserve the quality of the final product for practical applications. Currently, there is a need to find efficient and environmentally friendly solvents to replace the harmful volatile organic compounds that are conventionally used as extraction solvents. Therefore, alternative solvents with more benign and environmentally friendly characteristics are crucial to develop sustainable citrus essential oil deterpenation processes. In this work, biorenewable deep eutectic solvents (DES) composed of glycerol (Gly) and choline chloride (ChCl) are evaluated as sustainable solvents for citrus essential oil deterpenation, using model mixtures and real citrus crude orange essential oils (COEO). The liquid–liquid extraction process for essential oil deterpenation using DES was performed at 298.15 K and 101.3 kPa, and the solvent performance was evaluated in terms of the experimental solute distribution coefficients and selectivity values, which were compared against those predicted using the conductor-like screening model for real solvents (COSMO-RS). The effect of solvent composition (i.e., hydrogen bond acceptor/donor ratio) and the addition of water (pure DES vs diluted DES) were also explored. Overall results indicate the feasibility of using DES as extraction solvents for citrus essential oil deterpenation, with pure ChCl:Gly 1:2 providing the highest extraction yield, while the addition of water decreased the distribution coefficient but increased the selectivity of the process.
Article
Wastewater treatment plants do not properly address the removal of emerging micropollutants, such as pesticides, and thus these compounds contaminate water sources of public drinking water systems. In this context, this work focuses on the development of hydrophobic deep eutectic solvents (DESs), as cheap extractants for the removal of four neonicotinoids, Imidacloprid, Acetamiprid, Nitenpyram and Thiamethoxam, from diluted aqueous solutions. In particular, two different families of DESs, one based on natural neutral ingredients (DL-Menthol and natural organic acids) and the other based on quaternary ammonium salts and organic acids were prepared and their water stability carefully studied through ¹H NMR. Only the chemically stable DESs were selected to be used as solvents in the extraction of the four neonicotinoids so that no contamination of the water cycle is attained, while reuse of the DES is possible. The final results were compared with those obtained for liquid-liquid extraction using hydrophobic imidazolium-based ionic liquids as solvents.
Article
The prediction quality of COSMO-RS for the thermodynamic properties needed for the design of a liquid-liquid chromatographic process was evaluated for systems containing deep eutectic solvents (DES). Therefore activity coefficients, liquid-liquid equilibrium data, and partition coefficients of different solutes were computed and compared to experimental data from literature or measurements. The calculations were performed using TZVP and TZVPD-FINE parameterizations and fully dissociated and non-dissociated representations of the h-bond acceptor molecules. It was found that the predictions qualitatively resemble the trend of the experimental data. The TZVPD-FINE parameterization did not yield significantly lower deviations from the experimental values than TZVP, while calculations with the latter were up to ten times faster. Although DES constituents exhibit strong H-bond interactions, the representation as an electroneutral mixture is preferable. It could be shown that the predictions of partition coefficients are in good agreement with the measured values in the preferred working range of liquid-liquid chromatography. The overall prediction quality is sufficient to use the predictive model for the screening procedure for the solvent system selection.
Article
Molar enthalpies of mixing (HE) were measured for the following deep eutectic solvents (DESs): {choline chloride + glycerol}, {choline chloride + ethylene glycol}, {tetrabutylammonium chloride + glycerol}, and {tetrabutylammonium chloride + ethylene glycol} at 323.15 K and molar ratios of 1:4, 1:3, 1:2 and 1:1. Results show that all systems are endothermic, with HE values ranging from 1.90 to 5.35 kJ·mol–1. Results indicate that the intermolecular interactions between the molecules of the pure components are stronger than those of the DESs complexes. To shed some light on the mutual interactions between the molecules within the mixtures, effects of the hydrogen bond acceptor structure (HBA), hydrogen bond donor structure (HBD), and concentration (HBA:HBD molar ratio) were analyzed. The nature of the HBA salt is the most important: choline chloride-based systems required almost twice as much energy as tetrabutylammonium chloride-based systems in order to form the DES mixture, most likely because of a higher enthalpy of fusion of the choline-based HBA salt. Choline chloride is more stable than tetrabutylammonium chloride because of its hydroxyl group; consequently, more energy is needed to break the choline chloride interactions in order to form DES mixtures with glycerol or ethylene glycol. Other effects suggest a competition in the formation of hydrogen bonds among the pure species (like molecular interactions) and the DES complexes (unlike molecular interactions). Overall, this work reports a systematic evaluation of HE for a series of representative DESs that elucidates the roles of HBD and HBA in the energy penalty required for DES formation, which is critical for assessing their potential in practical applications on an industrial scale.
Article
Valorization of wastewater streams can be done by fermentation to produce volatile fatty acids (VFAs) which are applied as platform chemicals for synthesis of value-added chemicals. Since VFA concentration in fermented wastewater is very low (∼ 1 wt%) and fermented wastewater contains considerable amounts of dissolved salts, recovery of VFAs from fermented wastewater is challenging. To study the potential of some ionic liquids compared to traditional solvents for extraction of VFAs from fermented wastewater, a detailed study on the effects of various salt-originating ions on VFA extraction was performed. Ion exchange and intermolecular interactions (e.g. hydrogen bonding) were found to be responsible for extraction of VFAs. The presence of salts (e.g. KCl) resulted in extraction of acidic forms of salt-originating anions (e.g. H++Cl-). 20 wt% trioctylamine (TOA) in n-octanol (representing conventional solvents) and [P666,14][Phos] (an ionic liquid) were found to be the most promising VFA-extracting solvents. Their maximum VFA loadings while being in equilibrium with an artificial fermented wastewater were determined by performing cross-current extractions. [P666,14][Phos] achieved a higher maximum VFA loading which enables it to deliver a much more concentrated VFA stream at a lower solvent to feed ratio (S/F).
Chapter
The term ‘hydrophobic effect’ refers to the poor solubility of nonpolar substances in water compared to organic solvents or to polar substances. The transfer of small nonpolar molecules from the gas phase or organic solvents to water has a characteristic thermodynamic signature: positive free energy, negative enthalpy, large negative entropy and positive heat capacity. This thermodynamic signature can be explained by considering the structure of water around nonpolar substances, which depends on the size and shape of the nonpolar solute. The poor solubility of nonpolar groups in water leads to aggregation of these groups (hydrophobic interaction) and the formation of self-assembled structures such as miscelles and lipid bilayers. The hydrophobic interaction is also the major contributor to protein folding. The origin of the hydrophobic effect lies in the fact that water interacts with itself much more strongly than it does with nonpolar groups. Key Concepts: The origin of hydrophobicity lies in the strong water–water interactions.The hydrophobic effect is entropic or enthalpic depending on temperature and the geometry of the associating solutes.The characteristics of hydrophobic hydration differ depending on the length scale of the solute.The hydrophobic effect is responsible for the formation of lipid bilayers and the folding of proteins.Interaction between small hydrophobic solutes is in many ways different from transfer to a bulk phase.Most studies find anticooperativity in the interaction between three small nonpolar solutes.Very long-range attractions between hydrophobic surfaces are probably due to macroscopic phenomena, such as air bubbles.Keywords:water;hydrophobic;nonpolar;solvation;hydration;hydrogen bonding
Article
Biomass-derived succinic acid (Bio-SA) has been described as a strategic platform chemical, due to its potential as the C4 building block in industrial organic chemistry. Sustainability of SA production via fermentative synthesis was studied through two different processes (Myriant and Reverdia cases) and compared with the corresponding petrochemical route. Four groups of parameters, namely material efficiency, economics, energy efficiency and land use were considered. Green metrics results show that energy efficiency for Bio-SA production is slightly higher while material efficiency is rather lower when compared with the petrochemical counterpart. Remarkably, Bio-SA calculated costs (≈1040€/MT in the worse case) are quite lower than the actual prices for Petr.SA and close to the price of maleic anhydride used as raw material. Thus, bio-based SA production appears to be competitive with petrochemical route for MAN. Competitiveness of Bio-SA can be boosted by optimization of fermentative process, as well as by the Bio-SA upgrading to high added value chemicals.
Article
Mixtures of ionic liquids (ILs) and molecular amines have been suggested for CO2 capture applications. The basic idea is to replace water, which volatilizes in the amine regeneration step and increases the parasitic energy load, with a non-volatile ionic liquid solvent. To fully understand the thermodynamics of these systems, here experimental excess enthalpies for binary mixtures of monoethanolamine (MEA) and two ILs: 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [hmim][NTf2], and 1-(2-hydroxyethyl)-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [OHemim][NTf2], were obtained by calorimetry, using a Setaram C80 calorimeter, over the whole range of compositions at 313.15 K. Since it is the temperature derivative of the Gibbs energy, enthalpy is a sensitive measure of intermolecular interactions. MEA + [hmim][NTf2] is endothermic and MEA + [OHemim][NTf2] is exothermic. The reliability of COSMO-RS to predict the excess enthalpy of the (MEA+IL) systems was tested based on the implementation of two different molecular models to define the structure of the IL - the IL as separate cation and anion [C+A] and the IL as a bonded single specie [CA]. Quantum-chemical calculations were performed to gain additional insight into the intermolecular interactions between the components of the mixture. For MEA + [hmim][NTf2] both the [C+A] and [CA] models predict endothermic behavior, but the [CA] model is in better agreement with the experimental results. For MEA + [OHemim][NTf2] the [C+A] model provides the best match to the experimental exothermic results. However, what is really surprising is that two different conformations of the cation-anion pair with nearly identical energies in the [CA] model result in completely different (exothermic vs. endothermic) predictions of the excess enthalpy. Nonetheless, the results do show that the influence of the structure of the IL on the thermodynamic behavior of the mixture (endothermic vs. exothermic) can be attributed to hydrogen bonding between the cation and the MEA molecule. However, this study highlights the importance of carefully selecting the molecular model and conformation in order to obtain even qualitatively correct predictions with COSMO-RS. The fact that even very slightly different conformations of the IL can drastically change the thermodynamic estimations using COSMO-RS is of significant concern. Overall, we believe the present work provides a better understanding of the behavior of mixtures involving amines and ILs, which is an important aspect to consider when evaluating the use of such solvent mixtures in CO2 capture technologies.
Article
To properly screen and use ionic liquids (ILs) as environmental-friendly solvents in chemical reactors and separation processes, the knowledge of their solubilities with water is essential. In the present work, mutual solubilities of 1500 ILs (50 cations, 30 anions) with water at 298.15 K were predicted by using the conductor-like screening model for real solvents (COSMO-RS) as a thermodynamic model. On the basis of the COSMO-RS calculations, the influence of the types of anion and cation, side chain modifications and substituent groups on the mutual solubility with water was extensively analyzed. The data obtained can be used for the prescreening of ILs as solvent candidates. Moreover, to understand the intrinsic solubility behavior in detail, different types of molecular interactions between ILs and water in solution were compared on the basis of the determination of multiple water–IL interaction energies from COSMO-RS computation. The results confirm that hydrogen bonding interactions between anions and water molecules have the dominant influence on the solubility. Finally, for the purpose of fast solubility estimation and solvent selection, COSMO-RS derived molecular descriptors which indicate the strength of anionic HB acceptors were calculated for typical anions and anion families.
Article
A novel and very efficient method for the a priori prediction of thermophysical data of liquids is presented. It is based on unimolecular quantum chemical calculations that provide the necessary information for the evaluation of molecular interactions in liquids. Combined with a very fast and accurate statistical thermodynamics, the new method is an alternative to structure-interpolating group contribution methods (GCMs). The most important advantages are the essentially general applicability, the sound physical basis, and the graphicness of the procedure, which easily allows for chemical interpretation and understanding of thermophysical behaviour. A methodological comparison with GCMs is given. Example applications are presented.
Article
A biorefinery that supplements its manufacture of low value biofuels with high value biobased chemicals can enable efforts to reduce nonrenewable fuel consumption while simultaneously providing the necessary financial incentive to stimulate expansion of the biorefining industry. However, the choice of appropriate products for addition to the biorefinery's portfolio is challenged by a lack of broad-based conversion technology coupled with a plethora of potential targets. In 2004, the US Department of Energy (DOE) addressed these challenges by describing a selection process for chemical products that combined identification of a small group of compounds derived from biorefinery carbohydrates with the research and technology needs required for their production. The intent of the report was to catalyze research efforts to synthesize multiple members of this group, or, ideally, structures not yet on the list. In the six years since DOE's original report, considerable progress has been made in the use of carbohydrates as starting materials for chemical production. This review presents an updated evaluation of potential target structures using similar selection methodology, and an overview of the technology developments that led to the inclusion of a given compound. The list provides a dynamic guide to technology development that could realize commercial success through the proper integration of biofuels with biobased products.
Article
Tetraalkylphosphonium ionic liquid (IL) with a bis 2,4,4-trimethylpentylphosphinic anion (Cyphos IL-104) is an effective extractant of lactic acid (LA) achieving at low LA concentrations the distribution coefficients for aqueous systems above 40. L/L equilibrium data for pure Cyphos IL-104 and its solutions in n-dodecane have been measured. With increasing acid concentration the value of the distribution coefficient of LA decreases. Cyphos IL-104 extracts only undissociated molecules of lactic acid (LAH) via H-bonding. Increase in the concentration of IL-104 in n-dodecane results in increasing distribution coefficient of LA and the water solubility. The high water content in the solvents with Cyphos IL-104 is connected with the formation of reverse micelles. An interesting phenomenon of the liberation of water from the solvent in extraction of LA has been observed. It is suggested that splitting of the reverse micelles due to the formation of LAH/IL complexes occurs. With increasing temperature the values of the distribution coefficients of LA practically does not change or only slightly increases. In contrary to this, the increase in temperature decreased the water solubility in solvents containing IL-104. This is interpreted by the lower stability of reverse micelles at higher temperatures. Based on experimental equilibrium data the formation of stoichiometrically defined complexes with the structure (LAH)p(IL)(H2O)2 and (p, 1, 2) stoichiometry, where p is in the interval from 1 to 3, is suggested. The proposed model fits the equilibrium data well and indicates the domination of the (2, 1, 2) complex at medium aqueous acid concentrations in the interval from 0.2 to 2kmolm−3. There are two mechanisms of water extraction into the solvents with Cyphos IL-104: the formation of reverse micelles, and the formation of hydrated complexes of LAH with IL. A sharp decrease in the viscosity of solvents with IL-104 with increasing concentration of water or LA was observed.
Article
Organic acids constitute a key group among the building-block chemicals since they are extremely useful as starting materials for the chemical industry. However, the extraction processes of these acids from dilute waste water and fermentation broths normally use organic solvents which imply additional environmental hazards. In this work we have tested the efficiency of hydrophobic ionic liquids, namely phosphonium-based, to extract three short-chain organic acids (l-lactic, l-malic, and succinic acids) from dilute aqueous solutions, as model systems for the use of ionic liquids to extract bioproducts from fermentation broths. The effect of the anion’s nature and the concentration of the acid in the aqueous solution on the partition coefficients was evaluated. Two different approaches to recover the organic acid from the ionic liquid, viz. reduced pressure distillation and pH variation were assessed. The results gathered in this work proved that phosphonium-based ILs can be better extractants than the organic solvents traditionally used. In addition, the predictive capacity of the COSMO-RS for the ternary systems water + organic acid + ionic liquid was evaluated.
Article
Liquid-liquid equilibrium data of butyric acid in the systems water + solvent with tri-n-octylamine as extractant and n-alkanes as diluent, and water + pure n-alkanes are presented. The distribution coefficient is a linear function of the aqueous concentration of butyric acid for pure n-alkanes. For solvents containing trioctylamine, the dependence of the distribution coefficient of butyric acid goes through a maximum at a concentration of butyric acid of about 0.2 kmolâm-3. An overloading of the extractant reaching the value of almost 6 was observed. The loading is independent of the extractant concentration. The experimental data were interpreted by a chemical reaction mechanism and a related model in which the existence of (1,1) to (7,1) acid-amine complexes and a monomer and a dimer of butyric acid in the solvent was supposed. The equilibrium constants of formation of these complexes and the distribution of individual species in the solvent were estimated. This model fits experimental equilibrium data well. With increasing temperature, the value of the distribution coefficient of butyric acid decreases. Coextraction of water in the solvents is proportional to the concentration of butyric acid, and in the solvent with trioctylamine, it is 10 times higher than that in pure n-alkanes.
Article
A surge of progress in both laser spectroscopy experiments and theoretical dynamics methods has facilitated new, highly detailed studies of water clusters. The geometrical structures and hydrogen-bond tunneling pathways of the water trimer, tetramer, pentamer, and hexamer systems have recently been characterized with global analysis of potential surfaces, diffusion Monte Carlo calculations, and far-infrared laser vibration-rotation tunneling spectroscopy. Results from these and other studies are yielding important insights into the cooperativity effects in hydrogen bonding, aqueous solvation, and hydrogen-bond network rearrangement dynamics, which promise to enhance our understanding of solid and liquid water behavior.
Article
The focus of this investigation is the development of a fast and reliable extractant screening approach. Phenol extraction is selected as the model process. A quantum chemical conductor-like screening model for real solvents (COSMO-RS) is combined with molecular design considerations. For this purpose, phenol distribution coefficients KD of known phenol extractants are determined experimentally and in silico. Molecular variations of different extractants are tested concerning their effect on KD to facilitate extractant improvement. It is shown that KD depends on the molecular structure of the extractant. Calculations with COSMO-RS provide a qualitative trend of simulated extraction efficiency and even a quantitatively correct description of KD. The simulations for alkylamine components are, however, not accurate, which is a well-known problem. During the screening process, phosphorus containing aliphatic substances, especially the trialkylphosphine oxide compound Cyanex 923, were determined as the most promising phenol extractants, which agrees with the state of the art.
Article
The growing concern about the safety of food and dairy additives and the increasing costs of petroleum-based chemicals have rekindled the interest in the fermentation processes for fumaric acid production. The key problems of the industrial production of microbial fumaric acid are reviewed in this paper. Various strategies, including strain improvement, morphology control, substrate choice, fermentation process and separation process, are summarized and compared, and their economical possibilities for industrial processes are discussed. The market prospects and technological strategies for value-added fumaric acid derivatives are also addressed. The future prospects of microbial fumaric acid production are proposed at the end of this article.
Article
Lactic acid extraction was studied with two extractants, trioctyl amine (TOA) and Aliquat 336, in three diluents (methylisobutyl ketone (MIBK), octanol and paraffin liquid). The effects of organic phase extractant concentration and aqueous phase pH on the extraction process were examined. Among the extractants, TOA was found to be a better extractant than Aliquat 336 in all the diluents. In experiments with 50% (v/v) TOA in methylisobutyl ketone, 79% lactic acid could be extracted (initial lactic acid concentration 86·96 g dm−3). MIBK had a profound effect on the extraction behaviour of TOA in comparison with octanol and paraffin liquid while none of the diluents affected the extraction with Aliquat 336. The extraction of lactic acid was favoured at low pH. The toxicities of TOA and the diluents to Lactobacillus rhamnosus NRRL B445 were also studied. While TOA was found to be highly toxic at the molecular and the phase level, the paraffin liquid was totally non-toxic. The extraction of glucose and yeast extract by TOA and the diluents used was found to be low, which thus enables the selective extraction of lactic acid. © 1998 SCI
Article
ThermoML is an XML-based approach for storage and exchange of experimental and critically evaluated thermophysical and thermochemical property data. Extensions to the ThermoML schema for the expression of uncertainties are described. Basic principles, scope, and description of all new structural elements are discussed. Representation of upper and lower limits for property values is also addressed. ThermoML covers essentially all experimentally determined thermodynamic and transport property data (more than 120 properties) for pure compounds, multicomponent mixtures, and chemical reactions (including change-of-state and equilibrium). Properties of polymers and radicals and some properties of ionic systems are not represented at present. The present role of ThermoML in global data submission and dissemination is discussed with particular emphasis on cooperation between major journals in the field and the Thermodynamics Research Center (TRC) at the National Institute of Standards and Technology. The text of several data files illustrating the expression of uncertainties in ThermoML format for pure compounds, mixtures, and chemical reactions are provided as Supporting Information, as well as the complete updated ThermoML schema text.
Article
The solubility of water in tetradecyltrihexylphosphonium-based ionic liquids (ILs) with the bromide, bis(trifluoromethylsulfonyl)imide, bis(2,4,4-trimethylpentyl)phosphinate, chloride, decanoate, and dicyanimide anions was measured at temperatures between (288.15 and 318.15) K and atmospheric pressure. The effect of the nature of the IL anion, as well as the influence of temperature, are analyzed and discussed. From the experimental results, it was found that the anion-induced hydrophobicity increases from bis(2,4,4-trimethylpentyl)phosphinate < decanoate < chloride < bromide < dicyanimide < bis(trifluoromethylsulfonyl)imide. COSMO-RS, a predictive method based on unimolecular quantum chemistry calculations, was used to predict the solubility of the water−IL binary systems. COSMO-RS was found to provide fine qualitative and quantitative predictions of the experimental data for extremely hydrophobic ILs. Less accurate predictions were observed with the increase of the anion hydrophilic character.
Article
Two novel hydrophobic room temperature ionic liquids (RTIL) incorporating quaternary ammonium cations: tetrahexylammonium dihexylsulfosuccinate (THADHSS) and trioctylmethylammonium salicylate (TOMAS) have been obtained. The mutual solubility of the both RTILs with water and their Reichardt's polarity index have been measured. The extraction of aromatic amines and phenols into novel RTILs and two 1-alkyl-3-methylimidazolium bis(trifluoromethanesulfonyl)amides has been studied. The dependences of RTIL–water distribution ratio for the studied liquids on the phase volume ratio, the time of phase contact, pH value of aqueous solutions and the solute concentration have been obtained. In some cases, the solute distribution ratios for ammonium-based RTILs are as high as n × 104 that is much greater than for imidazolium ones. Notably, unlike the case of imidazolium-based RTILs, the quantitative extraction into ammonium RTILs is achieved even at the phase volume ratio VRTIL:Vw = 1:20.
Article
The methodology for the prediction of aqueous solubilities of solid organic compounds, and their temperature dependence, based on the Conductor-like Screening Model for Real Solvents (COSMO-RS/COSMOtherm) procedure, is presented and evaluated. The predictive capability of the quantum chemistry based program and the applied methodology was tested on the most common solid carboxylic acids. From the temperature dependence of the solubilities, the mean apparent enthalpies of solution were derived. The results obtained for a set of 27 carboxylic acids, consisting of aromatic carboxylic acids, dicarboxylic acids, as well as hydroxycarboxylic acids, are in good agreement with the experimental solubility data and their dependence with the temperature. The mean apparent enthalpies of solution, although of the same order of magnitude of the experimentally values, seem to be systematically underestimated.The good response of the applied methodology based on COSMOtherm/COSMO-RS on the prediction of non-ideal aqueous solubilities demonstrate the capability of this approach to predict and distinguish the solubility trends and magnitude, resulting from the substituent effects on the non-ideality of the aqueous solution.
Article
Succinic acid produced by various microorganisms can be used as a precursor of many industrially important chemicals in food, chemical and pharmaceutical industries. The assessment of raw material cost and the estimation of the potential market size clearly indicate that the current petroleum-based succinic acid process will be replaced by the fermentative succinic acid production system in the foreseeable future. This paper reviews processes for fermentative succinic acid production, especially focusing on the use of several promising succinic acid producers including Actinobacillus succinogenes, Anaerobiospirillum succiniciproducens, Mannheimia succiniciproducens and recombinant Escherichia coli. Processes for the recovery of succinic acid from fermentation broth are also reviewed briefly. Finally, we suggest further works required to improve the strain performance suitable for successful commercialization of fermentative succinic acid production.
Article
We performed the synergistic extraction of lactic acid with tri-n-butylphosphate (TBP) and alkylamines to find an optimum synergistic extraction system. We examined 12 alkylamines as co-extractants and found that extractability with alkylamines increases in order from tertiary>secondary>primary. Extractability increased with increasing alkyl chain length in trialkylamine; tri-n-octylamine (TOA) enabled the best extractability, however, further increases in chain length resulted in a decrease in extractability. The diluent effect was small due to a high concentration of TBP. We found that the synergistic extractions of lactic and succinic acids with TOA and TBP are exothermic processes.
Article
In order to develop new synergistic extraction system of organic acids, the extraction equilibria of organic acids (acetic, glycolic, propionic, lactic, succinic, fumaric, l-malic and itaconic, HnA) with tri-n-octylamine (TOA) and/or tri-n-butylphosphate (TBP) were measured. The solvation numbers of the acids were the same as the numbers of the carboxyl groups on each acid molecule in the extraction with TOA or TBP alone. The extraction equilibrium constants were roughly correlated with the hydrophobicity of the acid, except l-malic acid. In the case of using the mixed extractant of TBP and TOA, the synergism was observed in the extraction of all the acids investigated. Specially, the extractions of glycolic, lactic, succinic and fumaric acids gave a remarkable synergism. The extracted species were estimated to be HnA · 2TBP · TOA, in addition to HnA · (TOA)n and HnA · (TBP)n. The calculated results of the distribution ratio of organic acids based on the formation of three complexes explained well the experimental ones.
Article
The effect of water content on room-temperature ionic liquids (RTILs) was studied by Karl Fischer titration and cyclic voltammetry in the following ionic liquids: tris(P-hexyl)tetradecylphosphonium trifluorotris(pentafluoroethyl)phosphate [P14,6,6,6][NTf2], N-butyl-N-methyl-pyrrolidinium bis(trifluoromethylsulfonyl)imide [C4mpyrr][NTf2], 1-hexyl-3-methylimidazolium tris(perfluoroethyl)trifluorophosphate [C6mim][FAP], 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide [C4mim][NTf2], 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide [C4dmim][NTf2], N-hexyltriethylammonium bis(trifluoromethylsolfonyl)imide [N6,2,2,2][NTf2], 1-butyl-3-methylimidazolium hexafluorophosphate [C4mim][PF6], 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide [C2mim][NTf2], 1-butyl-3-methylimidazolium tetrafluoroborate [C4mim][BF4], 1-hexyl-3-methylimidazolium iodide [C4mim][I], 1-butyl-3-methylimidazolium trifluoromethylsulfonate [C4mim][OTf], and 1-hexyl-3-methylimidazolium chloride [C6mim][Cl]. In addition, electrochemically relevant properties such as viscosity, conductivity, density, and melting point of RTILs are summarized from previous literature and are discussed. Karl Fisher titrations were carried out to determine the water content of RTILs for vacuum-dried, atmospheric, and wet samples. The anion in particular was found to affect the level of water uptake. The hydrophobicity of the anions adhered to the following trend: [FAP]− > [NTf2]− > [PF6]− > [BF4]− > halides. Cyclic voltammetry shows that an increase in water content significantly narrows the electrochemical window of each ionic liquid. The electrochemical window decreases in the following order: vacuum-dried > atmospheric > wet at 298 K > 318 K > 338 K. The anodic and cathodic potentials vs ferrocene internal reference are also listed under vacuum-dried and atmospheric conditions. The data obtained may aid the selection of a RTIL for use as a solvent in electrochemical applications.
Article
In this paper, imidazolium-based ionic liquids [C(4)mim][PF(6)], [C(6)mim][PF(6)], [C(8)mim][PF(6)], [C(6)mim][BF(4)] and [C(8)mim][BF(4)] were tested as extracting solvents for removal of 3-indole butyric acid (IBA) from aqueous media with subsequent determination using HPLC. Percent extraction of IBA was strongly affected by pH of aqueous phases and the chemical structures of ionic liquids (ILs). Extraction of IBA was quantitative in the pH values lower than pK(a) of IBA. Considering both extraction and stripping efficiencies of IBA, [C(4)mim][PF(6)] was found to act more efficient than other studied ILs. Capacity of [C(4)mim][PF(6)] was 17.6x10(-4)mmol IBA per 1.0 mL of IL. Ionic strength of aqueous phase and temperature had shown no serious effects on extraction efficiency of IBA. A preconcentration factor of 100 and a relative standard deviation of 1.16% were obtained. It was found that ionic liquid phase was reusable almost five times for extraction/stripping purposes. 3-Indole acetic acid showed interferential effect in the extraction step. In order to assess the applicability of the method, extraction and stripping of IBA from pea plants and some other samples were studied.