Lipid extraction is regarded as a major bottleneck in an industrial-scale production of algae biodiesel because of the use of hazardous solvents and energy-intensive operations for cell disruption ...and solvent recovery. This study uses life cycle assessment (LCA) to evaluate the environmental impacts and primary energy demand (PED) of algae biodiesel production from “cradle to grave”, focusing for the first time on alternative solvents used for lipid extraction and to identify opportunities for process design improvements. Limonene, ethyl tert-butyl ether (ETBE), and cyclohexane are investigated alongside the benchmark solvent, hexane. The ReCiPe method is used to estimate 18 midpoint environmental impacts of “the production and combustion of 1 MJ of algae biodiesel”. Results show that the climate change (CC) and PED of algae biodiesel range from 94 to 101 g CO2 eq./MJ and 1.59 to 1.65 MJ/MJ, with hexane having the lowest CC and PED and limonene the highest. Lipid extraction is identified as the main hotspot in downstream processing due to the high energy consumption for cell disruption (i.e., high-pressure homogenization) and solvent recovery. The use of an acid pretreatment for cell disruption prior to lipid extraction reduces 11 out of 18 environmental impacts and PED of algae biodiesel for all solvents, including hexane. Overall, this study highlights the critical role of lipid extraction in algae biodiesel production and the need for improvements in solvents and process design. Moreover, the findings provide valuable insights that can be applied to improve the environmental sustainability of other extraction applications.
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•Removal of phenolic acids in solution using bio-based solvents was assessed.•Effect of key parameters on liquid–liquid extraction efficiency was studied.•Molecular structures played ...a significant role in the extraction process.•2-MeTFH provided the highest extraction and was successfully recycled.•Bio-based solvents are promising for phenolic acids recovery from aqueous matrices.
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 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.
•Sustainable valorization of white grape waste by recovering antioxidants was proposed.•A series of promising bio-renewable green solvents were evaluated as extractive agents.•EtOH and 2-MeTHF showed ...the highest selective extraction yields of phenolic compounds.•Recycling of solvents and recovery of antioxidants as a solid fraction was achieved.•The process was efficiently enhanced by ultrasound-assisted extraction.
Winemaking industry generates significant waste rich in bioactive compounds, particularly phenolic compounds with strong antioxidant properties. Bio-renewable green solvents are promising candidates for the sustainable recovery of such antioxidants. For these reasons, the aim of this study was to evaluate green solvents (alcohols, ethers, esters, and terpenes) for extracting phenolic compounds from white grape waste (WGW). The solid-liquid extraction process was optimized by adjusting parameters like extraction time, temperature, and solid:liquid ratio. Under most favourable conditions, ethanol yielded the highest total phenolic content at 9.43 ± 0.16 mg GAE/g WGW, followed by 2-methyltetrahydrofuran at 7.23 ± 0.08 mg. The total phenolic content of the different WGW fractions (skin and seeds) was also evaluated. The solvent extracts were analyzed by UV–Visible spectrophotometry and chromatographic (HPLC-DAD) methods to characterize the phenolic profile, and the antioxidant capacity was also measured. Alcohols and ethers emerged as the most selective solvents, particularly for catechin and gallic acid. Additionally, successful solvent recycling and antioxidant recovery as a solid fraction were accomplished. Lastly, ultrasound-assisted extraction intensified the process, reducing time and energy consumption. Overall, this work exemplifies the "Circular Bioeconomy" concept, promoting sustainable waste biomass valorization to produce high-value bioproducts in demand by industry and society.
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•Extraction efficiency of phenols and sugar from water using eutectic solvents was analyzed.•Phenol, guaiacol and syringol have shown high percentage of extraction.•Extraction of ...glucose from water is not possible using the studied eutectic mixtures.•The highest extraction efficiencies were obtained using HES 12.
Biomass can be transformed into energy, high value chemicals or bioethanol. Nevertheless, the production of the latter is limited by the presence of inhibitory compounds that hinder the sugar fermentation process. This paper proposes menthol-based Hydrophobic Eutectic Solvents (HESs) as green solvents in the liquid extraction of phenolic compounds from diluted aqueous solutions. In particular, the main goal of the work is to analyse the capacity of the HESs to extract phenolic compounds (phenol, guaiacol and syringol) and glucose (as model sugar), since both types of compounds are present in the aqueous phase generated after washing with water the oil obtained in the fast pyrolysis of the biomass. As this is a preliminary study, two model mixtures constituted by solute (phenolic compound or glucose) and deionized water were used. Once HESs were prepared using menthol and three organic acids (octanoic acid, decanoic acid and dodecanoic acid), liquid–liquid extractions were performed in order to test the ability of these solvents to extract the abovementioned compounds from water. Firstly, stirring and centrifuging times were optimized and the effect of varying the solvent/feed ratio and the initial concentration of the solution {phenolic compound + water} were studied. Afterwards, since the goal of this work is to remove phenols from water to enhance sugars fermentability, the liquid extraction of glucose from water using the same HESs were also experimentally carried out at the optimized conditions. The obtained results are very promising, as HESs can easily extract phenols but not glucose, which would improve the subsequent sugar fermentation process.
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•Carboxylic acid-based hydrophobic eutectic solvents were formed and characterized.•Extraction efficiency of hydrophobic eutectic solvents and bio-based solvents were obtained by ...HPLC-DAD/RI.•Selective extraction of phenols from sugar-rich aqueous streams could enhance fermentation processes.•Best selectivity and efficiency results were obtained with cyclopentyl methyl ether.•The experimental results were analyzed by means of COSMO-RS methodology.
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.
Life Cycle Assessment (LCA) has become the main approach for the environmental impact assessment of chemicals. Unfortunately, LCA studies often require large amounts of data, time, and resources. To ...circumvent this limitation, here we propose a streamlined LCA method that predicts the impact of chemicals from molecular descriptors, thermodynamic properties, and surface charge density distributions of molecules (COSMO-based σ-profiles). Our approach uses mixed-integer nonlinear models to automatically construct predictive equations of the life cycle impact of chemicals from a set of attributes that are more accesible than full LCA inventories. We applied our method to predict the life cycle impact of 90 chemicals from three attribute sets: 15 molecular descriptors, 12 thermodynamic properties, and discretized σ-profiles. Nine impact categories were estimated, including among others the Global Warming Potential and Eco-Indicator99. Results show that models based on molecular and σ-profile attributes show similar performance to those based on molecular and thermodynamic attributes. This facilitates the application of streamlined LCA when developing new chemicals and processes, avoiding the experimental determination of thermodynamic properties. Furthermore, molecular, thermodynamic, and σ-profile attributes used together provide the most accurate predictions. Overall, this work aims to enhance chemical environmental assessment, facilitating their screening and enhancing the development of more sustainable processes and products.
•A new method for the estimation of NRTL binary interaction parameters from liquid-liquid equilibrium data.•The method improves the phase stability of the solutions found.•The problem formulated can ...be solved in conventional mathematical computing software.
Fitting liquid-liquid equilibrium (LLE) data to common thermodynamic models (NRTL, UNIQUAC…) has been proved in the past to be a non trivial task. Many times it leads to inconsistent solutions where the Gibbs stability criteria is not satisfied. In this work, a simplified parameter estimation problem is formulated where the Gibbs stability criteria and the minimization of experimental and calculated phase composition distances, are simultaneously applied. This formulation is intended to be implemented in general mathematical computing software. Five isothermal ternary systems are studied and the obtained NRTL binary interaction parameters are compared with both existing published parameters and those obtained from commercial data regression tools. Results show that the combination of the proposed problem formulation with commercial non-linear programming solvers improves the quality of the ternary fittings obtained.
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•A novel method to predict environmental impacts of chemicals is proposed.•Molecular and thermodynamic attributes are used to predict environmental impacts.•A Mixed Integer Non-Linear ...Problem is solved to identify the best set of attributes.•The optimal prediction models combine molecular and thermodynamic predictors.•Some widely used impact categories (CED, GWP, EI99) are reasonably well predicted (20–40% error), while larger errors are attained in others.
Life Cycle Assessment (LCA) has recently gained wide acceptance in the environmental impact evaluation of chemicals. Unfortunately, LCA studies require large amounts of data that are hard to gather in practice, a critical limitation when assessing the processes and value chains present in the chemical industry. We here develop an approach that predicts the cradle-to-gate life cycle production impact of organic chemicals from attributes related to their molecular structure and thermodynamic properties. This method is based on a mixed-integer programming (MIP) optimisation framework that systematically constructs short-cut predictive models of life cycle impact. On applying our approach to a data set containing 88 chemicals, 17 molecular descriptors and 15 thermodynamic properties, we estimate with enough accuracy (for the purposes of a standard LCA) several impact categories widely applied in LCA studies, including the cumulative energy demand, global warming potential and Eco-indicator 99. Our framework ultimately leads to linear models that can be easily integrated into existing modelling and optimisation software, thereby facilitating the design of more sustainable processes.
The assessment of efficient and sustainable methods for extracting high-value compounds from natural products aligns with some of the statements proposed by the 12 Principles of Green Chemistry and ...17 Sustainable Development Goals. Replacing hazardous chemicals with safer alternatives, such as Natural Deep Eutectic Solvents (NADES), offers a promising and environmentally friendly approach. This review provides a comprehensive analysis of the composition of NADES, associated extraction techniques, and advancements in their use as an extraction media for bioactive compounds from their first report in 2013 until 2023. Moreover, an in-depth discussion of the terminology of NADES is presented and an updated and new term is suggested for specific combinations: Mixtures based on Natural Compounds (MINACs). Finally, prospective applications of such solvents are provided, complemented by insights into emerging trends and their potential to produce ready-to-use extracts.
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•NADES have emerged as green alternatives to conventional solvents.•Modern techniques, especially UAE, are employed with NADES.•A new term is proposed: Mixtures based on Natural Compounds (MINACs).•Ready-to-use extracts show high potential for the cosmetic and food industries.
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