Alternative Solvents for Green Chemistry

A special issue of Sustainable Chemistry (ISSN 2673-4079).

Deadline for manuscript submissions: closed (20 December 2022) | Viewed by 61264

Special Issue Editors


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LAQV, REQUIMTE, Department of Chemistry, NOVA School of Science and Technology, NOVA University of Lisbon, 2829-516 Caparica, Portugal
Interests: ionic liquids; chemical engineering; thermodynamic study; phase equilibria; separation processes
Special Issues, Collections and Topics in MDPI journals
LAQV, REQUIMTE, Department of Chemistry, NOVA School of Science and Technology, NOVA University Lisbon, 2829-516 Caparica, Portugal
Interests: development of ionic liquids and eutectic systems as novel, advanced, smart materials (critical evaluation in the field of green chemistry) and their study in separation/purification processes, aqueous biphasic systems, solubilisation and aggregation mechanisms, biomolecules purification, drug delivery; pharmaceutically active ionic liquids and eutectic systems; technologies for the removal and implementation of circular economy for fluorinated compounds (greenhouse fluorinated gases (F-gases) and PFAS)
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Sustainable or green chemistry aims to design products or processes that eliminate or minimize the use and production of hazardous compounds. Nowadays, an emerging research field of interest is the use of alternative solvents such as ionic liquids (ILs) and deep eutectic solvents (DES). ILs have become one of the increasingly popular “green” media for engineers, not only due to their remarkable properties but also for their recyclability. Additionally, ILs can be tailored for specific applications by accurately selecting the cation and/or the anion. More recently, DES are evolving as a new class of task-specific solvents that can overcome the major handicaps of some ILs, namely nonbiodegradability, complex synthesis and purification processes, and high cost.

Dr. Ana B. Pereiro
Dr. João M. M. Araújo
Guest Editors

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Keywords

  • Green solvents
  • Ionic liquids
  • Deep eutectic solvents
  • Sustainability

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Published Papers (15 papers)

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Research

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7 pages, 1152 KiB  
Communication
Recovery of Lac Resin from the Aqueous Effluent of Shellac Industry
by Gaurav Badhani, Shruti Yadav, Elen Reji and Subbarayappa Adimurthy
Sustain. Chem. 2023, 4(1), 1-7; https://doi.org/10.3390/suschem4010001 - 21 Dec 2022
Cited by 3 | Viewed by 2772
Abstract
Shellac and aleuritic acid manufacturing industries generate a lot of alkaline aqueous effluent during the process of manufacture of shellac and aleuritic acid from the seedlac/sticklac. The generated effluent contains lac resin, lac wax, lac dye and other water-soluble organic acids. Shellac industries [...] Read more.
Shellac and aleuritic acid manufacturing industries generate a lot of alkaline aqueous effluent during the process of manufacture of shellac and aleuritic acid from the seedlac/sticklac. The generated effluent contains lac resin, lac wax, lac dye and other water-soluble organic acids. Shellac industries in India face problems with the disposal of aqueous effluent due to the presence of considerable amounts of natural organic molecules and the dark colour solution. To address these problems, we have developed a novel method for the selective recovery of the lac resin from the alkaline aqueous effluent of shellac manufacturing industry. The recovered lac resin has been characterized by 13C-NMR, FT-IR and melting point and the data were compared with standard industrial-grade resin. The recovered lac resin was evaluated by the lac manufacturing industry for commercial applications. Full article
(This article belongs to the Special Issue Alternative Solvents for Green Chemistry)
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20 pages, 4749 KiB  
Article
Poly (Vinylidene Difluoride) Polymer in 1-Ethyl-3-methylimidazolium Acetate and Acetic Acid Containing Solvents: Tunable and Recoverable Solvent Media to Induce Crystalline Phase Transition and Porosity
by Santosh Govind Khokarale, Piotr Jablonski, Dariush Nikjoo, Van Minh Dinh, Ola Sundman, Knut Irgum and Jyri-Pekka Mikkola
Sustain. Chem. 2022, 3(4), 455-474; https://doi.org/10.3390/suschem3040028 - 29 Oct 2022
Viewed by 1906
Abstract
In this report, 1-ethyl-3-methylimidazolium acetate, [EMIM][AcO] ionic liquid (IL) and acetic acid (AA) comprised solvents were used for the thermal treatment of poly (vinylidene difluoride), PVDF. Here, besides the various combinations of IL and AA in solvents, the pure IL and AA were [...] Read more.
In this report, 1-ethyl-3-methylimidazolium acetate, [EMIM][AcO] ionic liquid (IL) and acetic acid (AA) comprised solvents were used for the thermal treatment of poly (vinylidene difluoride), PVDF. Here, besides the various combinations of IL and AA in solvents, the pure IL and AA were also applied as a solvent upon thermal treatments. The samples obtained after the treatment were analysed for structural and crystalline phase changes, porosity, and molecular weight distribution with various analytical techniques. The Kamlet-Taft parameters measurement of the IL and AA containing solvents with different solvatochromic dyes was also performed to examine their solvent properties and correlate with the properties of the treated PVDF materials. The treatment of PVDF with pure IL results in the formation of highly carbonaceous material due to extensive dehydroflurination (DHF) as well as possibly successive cross-linking in the polymer chains. Upon IL and AA combined solvent treatment, the neat PVDF which composed of both α- and β crystalline phases was transformed to porous and β-phase rich material whereas in case of pure AA the non-porous and pure α-phase polymeric entity was obtained. A combined mixture of IL and AA resulted in a limited the DHF process and subsequent cross-linking in the polymer chains of PVDF allowed the formation of a porous material. It was observed that the porosity of the thermally treated materials was steadily decreasing with increase in the amount of AA in solvents composition and solvent with an AA:IL mole ratio of 2:1 resulted in a PVDF material with the highest porosity amongst the applied solvents. A recovery method for the IL and AA combined solvent after the thermal treatment of PVDF was also established. Hence, with varying the type of solvents in terms of composition, the highly carbonaceous materials as well as materials with different porosities as well as crystalline phases can be obtained. Most importantly here, we introduced new IL and AA containing recoverable solvents for the synthesis of porous PVDF material with the electroactive β-phase. Full article
(This article belongs to the Special Issue Alternative Solvents for Green Chemistry)
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18 pages, 2081 KiB  
Article
Human Cytotoxicity, Hemolytic Activity, Anti-Inflammatory Activity and Aqueous Solubility of Ibuprofen-Based Ionic Liquids
by Joana C. Bastos, Nicole S. M. Vieira, Maria Manuela Gaspar, Ana B. Pereiro and João M. M. Araújo
Sustain. Chem. 2022, 3(3), 358-375; https://doi.org/10.3390/suschem3030023 - 13 Aug 2022
Cited by 7 | Viewed by 3623
Abstract
Ionic liquids (ILs) are a potential solution to the general problem of low solubility, polymorphism and low bioavailability of active pharmaceutical ingredients (APIs). In this work, we report on the synthesis of three pharmaceutically active ILs (API-ILs) based on ibuprofen, one of the [...] Read more.
Ionic liquids (ILs) are a potential solution to the general problem of low solubility, polymorphism and low bioavailability of active pharmaceutical ingredients (APIs). In this work, we report on the synthesis of three pharmaceutically active ILs (API-ILs) based on ibuprofen, one of the most commonly available over-the-counter nonsteroidal anti-inflammatory drugs (NSAIDs), with imidazolium cations ([C2C1Im][Ibu] and [C2(OH)C1Im][Ibu]) and a cholinium cation ([N1112(OH)][Ibu]). An upgrade to the aqueous solubility (water and biological simulated fluids) for the ibuprofen-based ILs relative to the ibuprofen’s neutral and salt form (sodium ibuprofen) was verified. The cytotoxic profiles of the synthesized API-ILs were characterized using two human cells lines, Caco-2 colon carcinoma cells and HepG-2 hepatocellular carcinoma cells, up to ibuprofen’s maximum plasma concentration (Cmax) without impairing their cytotoxicity response. Additionally, the EC50 in the Caco-2 cell line revealed similar results for both parent APIs and API-ILs. The biocompatibility of the ibuprofen-based ILs was also evaluated through a hemolytic activity assay, and the results showed that all the ILs were hemocompatible at concentrations higher than the ibuprofen Cmax. Moreover, the anti-inflammatory properties of the API-ILs were assessed through the inhibition of bovine serum albumin (BSA) denaturation and inhibition of cyclooxygenases (COX-1 and COX-2). The results showed that [C2C1Im][Ibu], [C2(OH)C1Im][Ibu] and [N1112(OH)][Ibu] maintained their anti-inflammatory response to ibuprofen, with improved selectivity towards COX-2, allowing the development of safer NSAIDs and the recognition of new avenues for selective COX-2 inhibitors in cancer chemotherapy and neurological diseases such as Alzheimer’s and Parkinson’s. Full article
(This article belongs to the Special Issue Alternative Solvents for Green Chemistry)
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11 pages, 677 KiB  
Article
Impact of Solvent Type on Total Phenol and Flavonoid Content and Sun Protection Factor of Crude Cashew Nutshell Liquid
by Kadango Zombe, James Nyirenda, Agape Lumai and Hellen Phiri
Sustain. Chem. 2022, 3(3), 334-344; https://doi.org/10.3390/suschem3030021 - 6 Jul 2022
Cited by 12 | Viewed by 3197
Abstract
Cashew nutshell liquid (CNSL) is a cheap source of natural phenolic compounds that have numerous applications. These phenolic compounds have chemical structures with chromophores similar to those found in synthetic chemical UV-filters, which are present in commercial sunscreen products (SSPs). Thus, this study [...] Read more.
Cashew nutshell liquid (CNSL) is a cheap source of natural phenolic compounds that have numerous applications. These phenolic compounds have chemical structures with chromophores similar to those found in synthetic chemical UV-filters, which are present in commercial sunscreen products (SSPs). Thus, this study investigated the impact of solvents on the yield, total phenol content (TPC), total flavonoid content (TFC), and the sun protection factor (SPF) of crude CNSL. The percent yield ranged from (30.4 ± 0.7% to 49.3 ± 3.2%); hexane recorded the lowest yield, while ethanol recorded the highest. Acetone (101.2 ± 2.5 mg GA/g), methanol (99.5 ± 0.10), and chloroform (95.4 ± 3.7 mg GAE/g), recorded the highest TPC respectively, while hexane (33.3 ± 0.7 mg QE/g) recorded the highest TFC. The SPFs ranged from (22.1 ± 1.1 to 16.4 ± 0.8), chloroform (22.1 ± 1.1), acetone (21.5 ± 1.1), and methanol (19.3 ± 1.0) again recorded the highest values respectively, while hexane (16.4 ± 0.8) recorded the lowest. Our results revealed that extracting solvents has a significant impact on the yield and SPF of CNSL. Therefore, we propose that acetone, chloroform, and methanol, either alone or as mixtures, could be the best solvents for extracting CNSL with a good TPC and SPF. Full article
(This article belongs to the Special Issue Alternative Solvents for Green Chemistry)
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10 pages, 3849 KiB  
Article
Comparison of Electrochemical Polishing Treatments between Phosphoric Acid and a Deep Eutectic Solvent for High-Purity Copper
by Tarek M. Abdel-Fattah and Jon Derek Loftis
Sustain. Chem. 2022, 3(2), 238-247; https://doi.org/10.3390/suschem3020015 - 19 May 2022
Cited by 2 | Viewed by 3256
Abstract
This study investigated and compared the acid-free electropolishing of copper with the state-of-the-art acidic electropolishing process. The acid-free medium used in this study is based on a deep eutectic solvent comprised of 2:1 ethylene glycol and choline chloride. The electrochemical study included voltammetry [...] Read more.
This study investigated and compared the acid-free electropolishing of copper with the state-of-the-art acidic electropolishing process. The acid-free medium used in this study is based on a deep eutectic solvent comprised of 2:1 ethylene glycol and choline chloride. The electrochemical study included voltammetry and chronoamperometry tests during the electropolishing process. The characterization techniques used were atomic force microscopy (AFM) and digital microscopy, and surface morphology comparisons summarized the electropolishing efficiency of phosphoric acid and acid-free deep eutectic solvent treatments for high-purity copper. Electropolishing copper with a deep eutectic solvent resulted in a mirror finish and a post-treatment surface that was 8× smoother than the original metal surface prior to electropolishing treatments with a smoothing efficiency of 91.1 ± 1.5%. This eco-friendly solution produced polished surfaces superior to those surfaces treated with industry standard acid electrochemistry treatments of 1 M H3PO4. Full article
(This article belongs to the Special Issue Alternative Solvents for Green Chemistry)
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18 pages, 5539 KiB  
Article
Efficient Extraction of the RuBisCO Enzyme from Spinach Leaves Using Aqueous Solutions of Biocompatible Ionic Liquids
by Ana I. Valente, Ana M. Ferreira, Mafalda R. Almeida, Aminou Mohamadou, Mara G. Freire and Ana P. M. Tavares
Sustain. Chem. 2022, 3(1), 1-18; https://doi.org/10.3390/suschem3010001 - 24 Dec 2021
Cited by 6 | Viewed by 7831
Abstract
Ribulose-1,5-biphosphate carboxylase/oxygenase (RuBisCO) is the most abundant protein on the planet, being present in plants, algae and various species of bacteria, with application in the pharmaceutical, chemical, cosmetic and food industries. However, current extraction methods of RuBisCO do not allow high yields of [...] Read more.
Ribulose-1,5-biphosphate carboxylase/oxygenase (RuBisCO) is the most abundant protein on the planet, being present in plants, algae and various species of bacteria, with application in the pharmaceutical, chemical, cosmetic and food industries. However, current extraction methods of RuBisCO do not allow high yields of extraction. Therefore, the development of an efficient and selective RuBisCOs’ extraction method is required. In this work, aqueous solutions of biocompatible ionic liquids (ILs), i.e., ILs derived from choline and analogues of glycine-betaine, were applied in the RuBisCO’s extraction from spinach leaves. Three commercial imidazolium-based ILs were also investigated for comparison purposes. To optimize RuBisCO’s extraction conditions, response surface methodology was applied. Under optimum extraction conditions, extraction yields of 10.92 and 10.57 mg of RuBisCO/g of biomass were obtained with the ILs cholinium acetate ([Ch][Ac]) and cholinium chloride ([Ch]Cl), respectively. Circular dichroism (CD) spectroscopy results show that the secondary structure of RuBisCO is better preserved in the IL solutions when compared to the commonly used extraction solvent. The obtained results indicate that cholinium-based ILs are a promising and viable alternative for the extraction of RuBisCO from vegetable biomass. Full article
(This article belongs to the Special Issue Alternative Solvents for Green Chemistry)
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15 pages, 3833 KiB  
Article
Alkali Iodide Deep Eutectic Solvents as Alternative Electrolytes for Dye Sensitized Solar Cells
by Hugo Cruz, Ana Lucia Pinto, Noémi Jordão, Luísa A. Neves and Luís C. Branco
Sustain. Chem. 2021, 2(2), 222-236; https://doi.org/10.3390/suschem2020013 - 6 Apr 2021
Cited by 12 | Viewed by 3999
Abstract
Different alkali deep eutectic solvents (DES), such as LiI:nEG, NaI:nEG, and KI:nEG, have been tested as electrolytes for dye sensitized solar cells (DSSCs). These DSSCs were prepared using pure DES or, alternatively, DES combined with different amounts of iodine (I2). The [...] Read more.
Different alkali deep eutectic solvents (DES), such as LiI:nEG, NaI:nEG, and KI:nEG, have been tested as electrolytes for dye sensitized solar cells (DSSCs). These DSSCs were prepared using pure DES or, alternatively, DES combined with different amounts of iodine (I2). The most important parameters, such as open circuit voltage (VOC), short circuit current density (JSC), fill factor (FF), and the overall conversion efficiency (η), were evaluated. Some DES seem to be promising candidates for DSSC applications, since they present higher VOC (up to 140 mV), similar FF values but less current density values, when compared with a reference electrolyte in the same experimental conditions. Additionally, electrochemical impedance spectroscopy (EIS) has been performed to elucidate the charge transfer and transport processes that occur in DSSCs. The values of different resistance (Ω·cm2) phenomena and recombination/relaxation time (s) for each process have been calculated. The best-performance was obtained for DES-based electrolyte, KI:EG (containing 0.5 mol% I2) showing an efficiency of 2.3%. The efficiency of this DES-based electrolyte is comparable to other literature systems, but the device stability is higher (only after seven months the performance of the device drop to 60%). Full article
(This article belongs to the Special Issue Alternative Solvents for Green Chemistry)
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18 pages, 5140 KiB  
Article
Unveiling the Influence of Non-Toxic Fluorinated Ionic Liquids Aqueous Solutions in the Encapsulation and Stability of Lysozyme
by Margarida L. Ferreira, Nicole S. M. Vieira, João M. M. Araújo and Ana B. Pereiro
Sustain. Chem. 2021, 2(1), 149-166; https://doi.org/10.3390/suschem2010010 - 4 Mar 2021
Cited by 9 | Viewed by 3132
Abstract
Proteins are bioactive compounds with high potential to be applied in the biopharmaceutical industry, food science and as biocatalysts. However, protein stability is very difficult to maintain outside of the native environment, which hinders their applications. Fluorinated ionic liquids (FILs) are a promising [...] Read more.
Proteins are bioactive compounds with high potential to be applied in the biopharmaceutical industry, food science and as biocatalysts. However, protein stability is very difficult to maintain outside of the native environment, which hinders their applications. Fluorinated ionic liquids (FILs) are a promising family of surface-active ionic liquids (SAILs) that have an amphiphilic behavior and the ability to self-aggregate in aqueous solutions by the formation of colloidal systems. In this work, the protein lysozyme was selected to infer on the influence of FILs in its stability and activity. Then, the cytotoxicity of FILs was determined to evaluate their biocompatibility, concluding that the selected compounds have neglected cytotoxicity. Therefore, UV–visible spectroscopy was used to infer the FIL-lysozyme interactions, concluding that the predominant interaction is the encapsulation of the lysozyme by FILs. The encapsulation efficiency was also tested, which highly depends on the concentration and anion of FIL. Finally, the bioactivity and thermal stability of lysozyme were evaluated, and the encapsulated lysozyme keeps its activity and thermal stability, concluding that FILs can be a potential stabilizer to be used in protein-based delivery systems. Full article
(This article belongs to the Special Issue Alternative Solvents for Green Chemistry)
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12 pages, 3394 KiB  
Article
Ecotoxicity and Hemolytic Activity of Fluorinated Ionic Liquids
by Nicole S. M. Vieira, Ana L. S. Oliveira, João M. M. Araújo, Maria Manuela Gaspar and Ana B. Pereiro
Sustain. Chem. 2021, 2(1), 115-126; https://doi.org/10.3390/suschem2010008 - 2 Mar 2021
Cited by 7 | Viewed by 2960
Abstract
The task-specific design of ionic liquids (ILs) has emerged in several industrial and pharmaceutical applications. The family of ILs with fluorine tags equal to or longer than four carbon atoms, the fluorinated ionic liquids (FILs), combine the best properties of ILs with the [...] Read more.
The task-specific design of ionic liquids (ILs) has emerged in several industrial and pharmaceutical applications. The family of ILs with fluorine tags equal to or longer than four carbon atoms, the fluorinated ionic liquids (FILs), combine the best properties of ILs with the ones of perfluorinated compounds, and are being designed for several specific purposes. In the pharmaceutical field, there is an urgency to search for novel antibacterial agents to overcome problems associated to antimicrobial resistances. Then, the main purpose of this work is to evaluate the environmental impact and the ability of FILs to be used as antibacterial agents against Pseudomonas stutzeri bacteria. Beyond its rare pathogenicity, these bacteria are also used as a bioremediation agent to treat several contamination sites. Then, it is important to determine which FILs have antibacterial properties, and which do not impact the bacterial growth. The biocompatibility of FILs was also evaluated through their hemolytic activity and represent a step forward the application of FILs in pharmaceutical applications. The results proved that high concentrations of FILs can have a reduced ecotoxicity and a high biocompatibility. [C8C1Im][CF3SO3] was identified as the most promising compound to be used as an antibacterial agent since it prevents the growth of bacteria at concentrations compatible with the red blood cells’ viability. Full article
(This article belongs to the Special Issue Alternative Solvents for Green Chemistry)
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11 pages, 4024 KiB  
Article
On the Dissolution of Metals in Ionic Liquids 1. Iron, Cobalt, Nickel, Copper, and Zinc
by Jéssica D. S. Vicente, Domingas C. Miguel, Afonso M. P. Gonçalves, Diogo M. Cabrita, José M. Carretas, Bruno J. C. Vieira, João C. Waerenborgh, Dulce Belo, António P. Gonçalves and João Paulo Leal
Sustain. Chem. 2021, 2(1), 63-73; https://doi.org/10.3390/suschem2010005 - 7 Feb 2021
Cited by 4 | Viewed by 2963
Abstract
Ionic liquids are critical reagents for science and technical processes nowadays. Metals are the most used reagents in the industry. It is crucial to have a deeper understanding of how ionic liquids and metals could interact. In this article the interaction of those [...] Read more.
Ionic liquids are critical reagents for science and technical processes nowadays. Metals are the most used reagents in the industry. It is crucial to have a deeper understanding of how ionic liquids and metals could interact. In this article the interaction of those two families of compounds is accessed. The dissolution (reaction) of metals with ionic liquids is studied, namely the influence of temperature, redox potential, and availability of an oxidant in the process. The final state achieved by the iron metal samples was also addressed by Mössbauer spectroscopy. Full article
(This article belongs to the Special Issue Alternative Solvents for Green Chemistry)
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8 pages, 1022 KiB  
Communication
Biocatalyzed Sulfoxidation in Presence of Deep Eutectic Solvents
by Gonzalo de Gonzalo
Sustain. Chem. 2020, 1(3), 290-297; https://doi.org/10.3390/suschem1030019 - 12 Nov 2020
Cited by 7 | Viewed by 2412
Abstract
The flavin-containing monooxygenase from Methylophaga sp. strain SK1 (mFMO) is a valuable biocatalyst for the preparation of optically active sulfoxides, among other valuable compounds. In this study, we explored to benefits of using Natural Deep Eutectic Solvents (NADESs) when doing oxidation [...] Read more.
The flavin-containing monooxygenase from Methylophaga sp. strain SK1 (mFMO) is a valuable biocatalyst for the preparation of optically active sulfoxides, among other valuable compounds. In this study, we explored to benefits of using Natural Deep Eutectic Solvents (NADESs) when doing oxidation with this biocatalyst, fused to phosphite dehydrogenase for cofactor regeneration (PTDH-mFMO). It was found that optically active sulfoxides could be obtained with slightly higher conversions in 10% v/v NADES when working at substrate concentrations of 50–200 mM, whereas there was no loss in the enantioselectivity. With these results, it is demonstrated for the first time that flavin-containing monooxygenases can be employed as biocatalysts in presence of NADESs. Full article
(This article belongs to the Special Issue Alternative Solvents for Green Chemistry)
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13 pages, 344 KiB  
Article
Phenol Recovery from Aromatic Solvents by Formation of Eutectic Liquids with Trialkyl-2,3-dihydroxypropylammonium Chloride Salts
by Emily L. Byrne and John D. Holbrey
Sustain. Chem. 2020, 1(1), 49-61; https://doi.org/10.3390/suschem1010004 - 9 Jun 2020
Cited by 4 | Viewed by 3145
Abstract
Trialkyl-2,3-dihydroxypropylammonium chloride salts have been investigated as liquid eutectic-forming salts for the extraction of phenol from aromatic-rich model oil (toluene), demonstrating how the increased partitioning of phenol from oil-phases can be combined with reduced co-miscibility of the salt with aromatic hydrocarbons through the [...] Read more.
Trialkyl-2,3-dihydroxypropylammonium chloride salts have been investigated as liquid eutectic-forming salts for the extraction of phenol from aromatic-rich model oil (toluene), demonstrating how the increased partitioning of phenol from oil-phases can be combined with reduced co-miscibility of the salt with aromatic hydrocarbons through the introduction of the dihydroxypropyl-function. Full article
(This article belongs to the Special Issue Alternative Solvents for Green Chemistry)
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Review

Jump to: Research

17 pages, 4480 KiB  
Review
Green Chemistry Approach for Fabrication of Polymer Composites
by Blessy Joseph, Saravanan Krishnan, Sagarika Vadakke Kavil, Avinash Rajalakshman Pai, Jemy James, Nandakumar Kalarikkal and Sabu Thomas
Sustain. Chem. 2021, 2(2), 254-270; https://doi.org/10.3390/suschem2020015 - 9 Apr 2021
Cited by 8 | Viewed by 4965
Abstract
Solvents are an inevitable part of industries. They are widely used in manufacturing and processing industries. Despite the numerous controlling measures taken, solvents contaminate our environment to a vast extent. Green and sustainable solvents have been a matter of growing interest within the [...] Read more.
Solvents are an inevitable part of industries. They are widely used in manufacturing and processing industries. Despite the numerous controlling measures taken, solvents contaminate our environment to a vast extent. Green and sustainable solvents have been a matter of growing interest within the research community over the past few years due to the increasing environmental concerns. Solvents are categorized as “green” based on their nonvolatility, nonflammability, availability, biodegradability and so on. The use of ionic liquids, super critical carbon dioxide and aqueous solvents for the fabrication of polymer composites is discussed in this review. The progress of utilizing solvent-free approaches for polymer composite preparation and efforts to produce new biobased solvents are also summarized. Full article
(This article belongs to the Special Issue Alternative Solvents for Green Chemistry)
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18 pages, 9521 KiB  
Review
Review on Hydrometallurgical Recovery of Metals with Deep Eutectic Solvents
by Guillaume Zante and Maria Boltoeva
Sustain. Chem. 2020, 1(3), 238-255; https://doi.org/10.3390/suschem1030016 - 3 Oct 2020
Cited by 60 | Viewed by 7670
Abstract
Deep eutectic solvents (DESs) appeared recently as a new class of green designer solvents. The recovery of metals using hydrometallurgy is of major importance with the growth in metal demand. Several authors used these solvents for the hydrometallurgical recovery of metals from primary [...] Read more.
Deep eutectic solvents (DESs) appeared recently as a new class of green designer solvents. The recovery of metals using hydrometallurgy is of major importance with the growth in metal demand. Several authors used these solvents for the hydrometallurgical recovery of metals from primary and secondary resources, and these studies are reviewed in the present work. Hydrophilic DESs can be used for the leaching of metals and have great potential to replace mineral acids, and even to reduce water consumption. Efficient and selective leaching of metals from minerals or wastes is feasible by using DESs. However, the kinetics of leaching as well as the physicochemical properties of DESs are still limiting their large-scale application. Electrochemical recovery from DES is also possible but deserves further investigation. Finally, the recovery of metals from aqueous solutions using hydrophobic DESs was studied in several works. For the solvent extraction of metals, hydrophobic DESs constitute credible alternative ionic liquids. Full article
(This article belongs to the Special Issue Alternative Solvents for Green Chemistry)
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22 pages, 3025 KiB  
Review
Recent Trends in Processing of Proteins and DNA in Alternative Solvents: A Sustainable Approach
by Rosy Alphons Sequeira, Jitkumar Bhatt and Kamalesh Prasad
Sustain. Chem. 2020, 1(2), 116-137; https://doi.org/10.3390/suschem1020010 - 25 Aug 2020
Cited by 24 | Viewed by 4879
Abstract
Throughout numerous research works on biomacromolecules, several breakthrough innovations have occurred in the field of biomacromolecule processing. Remarkable improvements have been made so far to address the problems associated with biomacromolecule processing technologies in terms of enhancing the efficiency of the processes. Green [...] Read more.
Throughout numerous research works on biomacromolecules, several breakthrough innovations have occurred in the field of biomacromolecule processing. Remarkable improvements have been made so far to address the problems associated with biomacromolecule processing technologies in terms of enhancing the efficiency of the processes. Green technology broadly focuses on the search for new techno-economic systems to replace the conventional systems which exhibit pernicious consequences for the environment and the health of organisms. The strategy practiced popularly is the use of alternate solvent systems, replacing the conventional toxic, volatile, and harsh organic solvents to prevent denaturation, biotransformation, enzyme activity loss, and degradation of biomacromolecules. Ionic liquids (ILs) and deep eutectic solvents (DESs) are emerging as greener alternatives over the past two decades and there has been an exponential increase in reports in the literature. The utility of neoteric solvents in biomacromolecule treatment may be envisaged for industrial processes in the near future. The current state of the art regarding the recent developments made over the past few years using neoteric solvents has been reviewed in this article. The recent scientific developments regarding the use of these neoteric solvents, especially ILs and DESs, for processes such as solubilization, extraction, and functionalization of biomacromolecules, especially proteins and DNA, have been addressed in this article. This review may be beneficial for designing novel and selective methodologies for the processing of biomacromolecules, opening doors for better material research in areas such as biotechnology and biological sciences. Full article
(This article belongs to the Special Issue Alternative Solvents for Green Chemistry)
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