Ternary Deep Eutectic Solvent Research Articles

Phase-separated solvothermal high yields recovery of lithium and cobalt cathode precursors from end-of-life LiCoO2 lithium-ion batteries

Lithium-ion batteries (LIBs) recycling is one of the most urgent challenges affecting this technological sector. Indeed, their continuously growing production and demand is already leading to the creation of large volumes of end-of-life LIBs (EoL-LIBs). At the same time, the growing demand for LIBs is not sustainable from the point of view of supply of the critical raw materials needed to produce the essential components of LIBs. The development of efficient and sustainable recycling strategies provides a solution to these two urgent issues. Here we propose a new ternary deep eutectic solvent (DES) composition based on choline chloride, citric acid, and ethylene glycol in molar ratio 1:1:1 for the reductive degradation of LiCoO2 cathode. The optimized leaching process (5g of DES for 100 mg of black mass for 30 min at 140 °C) leads to the full degradation of the cathode with extraction yields above 97% for both Li and Co. Simple electrochemical tests confirm irreversible DES degradation, making its recovery and reuse impractical. We demonstrate that a subsequent thermal treatment, using DES as a sacrificial agent, allows to separate and recover Co3O4 and LiCl with adequate purity to be exploited for LiCoO2 resynthesis. As a proof of concept, a new batch of LiCoO2 is synthesized and used for new cells’ assembly. The performance of the resynthesized material is comparable with that of the commercial benchmark material, demonstrating the possibility of a full closed-loop recycling route.

A green extraction technology of lignocellulose from cassava residue by mechanical activation-assisted ternary deep eutectic solvent

Lignocellulose (LC) is a natural polymer material that holds immense potential for various applications. However, extracting LC from biomass wastes with high-starch content has been challenging due to low selectivity and yield. In this study, LC was prepared from cassava residue (CR) via a combination of mechanical activation pretreatment and a citric acid (CA)-enhanced ternary deep eutectic solvent (TDES) consisting of choline chloride (ChCl), lactic acid (LA), and CA. The mechanical activation reduces the size of CR, greatly promoting the removal ability for starch, lignin and hemicellulose using TDES, and thus improving yield and selectivity of LC through this method. The CA esterified LC to prevent its excessive hydrolysis and increased a significantly higher LC content (82.52 wt%) compared to mechanical activation only and DES without CA, increasing by 6.97 times and 1.26 times, respectively. The extraction temperature significantly affected the structure, composition, thermal stability of LC and the properties of recovered TDES. The LC extracted at 90 °C (LC-90) had the highest cellulose content (82.52 wt%), crystallinity index (44.82 %), and higher degradation temperature (339.7 °C). The properties of the recovered TDES and extraction mechanism were analyzed. This study provides a strategy for the high-value utilization of biomass waste.

Novel ternary deep eutectic solvents pretreatment of corn stalk to realize high-value utilization

The high-valued utilization of biomass components through pretreatment technology can effectively alleviate the pressure of energy and environment. In this study, a ternary deep eutectic solvent (TDES) was prepared by using glycolic acid (GA) and ethylene glycol (EG) as double hydrogen donors and benzyl trimethyl ammonium chloride (TMBAC) as hydrogen acceptor. The corn stalk was separated by TDES to obtain cellulose-rich solid residue and low-condensed lignin. Moreover, the solid residue was converted into bio-oil by rapid pyrolysis, and the low-condensed lignin was converted into fluorescent lignin by grafting luminol for information encryption. The results showed that under the pretreatment condition of 150℃ for 3 h, TDES with the molar ratio of 1:1:2 had a lignin removal ratio of 90.60 %, and the yield of levoglucosan obtained from solid residue pyrolysis bio-oil reached 36.38 %. Furthermore, TDES prevented lignin from forming a C-C polycondensation structure and endowed it with polyhydroxy properties, which was beneficial to graft luminolto enhance the fluorescence intensity efficiently. The high-intensity fluorescent grafted lignin was used for information encryption of various materials. The mechanism of TDES pretreatment and luminol grafting were explored, and the mass balance of corn stalk during pretreatment was described. This study provides a green, environmentally friendly, and efficient pretreatment process for the high-value utilization of biomass.

Efficient β-carotene recovery from surfactant-based aqueous solutions: Advancing from experimental to process simulation

β-carotene is a carotenoid present in the human diet with numerous functions in the body. This work suggests a new platform for efficiently recovering this bioactive compound from aqueous solutions. For the first time, a ternary deep eutectic solvent (DES) is proposed to promote phase separation in aqueous solutions of non-ionic surfactants (Triton X-102 and Tween 20). The influence of temperature on the miscibility regions was investigated from 298.15 K to 308.15 K as a preliminary step. The obtained phase diagrams at three temperatures were accurately correlated using four empirical equations. The extraction capacity of these novel combinations was analysed by means of the Tie-Lines (TL) and their derived magnitudes: Tie-Line Length (TLL) and Slope (S). The reliability of the TLs was ascertained through three empirical equations. Analysis of the data showed that more than 99 % of the model carotene could be extracted using ChCl:U:Gly from a Triton X-102 aqueous solution at 308.15 K. Process simulation using SuperPro Designer confirmed that an effective and sustainable process for recovering β-carotene from algal biomass can be designed using a simple approach.

Activation of muscle amine functional groups using eutectic mixture to enhance tissue adhesiveness of injectable, conductive and therapeutic granular hydrogel for diabetic ulcer regeneration

Herein, Polydopamine-modified microgels and microgels incorporated with superficial epoxy groups were synthesized and applied as precursors for the fabrication of four granular hydrogels. To enhance the tissue adhesiveness, a ternary deep eutectic solvent was synthesized to activate the muscle amine functional groups facilitating the formation of robust NC bonds at ambient conditions. At a certain shear rate of 10 s−1, hydrogel DMG displayed a viscosity of 9×103 Pa/s, representing the highest complex viscosity among the tested hydrogels primarily driven by quinone groups in PDA which enhanced reversible interactions, thereby increasing particle cohesion. Moreover, the intersection point escalating from about 4×103 to approximately 9×104 as the concentration of DMG increased from 0 % (for MG) to 70% (7D3MG) by weight. There was a decrease in adhesion strength from 0.45 ± 0.08 N in MG to 0.39 ± 0.16 N, 0.35± 0.18 N, and 0.33 ± 0.15 N for 3D7MG, 7D3MG, and DMG respectively, suggesting that MG was capable of forming numerous covalent bonds, thereby enhancing its adhesion to the substrate. The type of eutectic mixture affected the electrical conductivity and a very important point was the changes in resistance value with time. For MG catalyzed by [DES]AZG, the resistance increased only by 1.3 % (from 3.37 to 3.81 kΩ) at day 3 and 37.09 % (from 3.37 to 4.62 kΩ) at day 5. The 3D7MG hydrogel exhibited superior therapeutic efficacy toward diabetic wound regeneration. The proliferation index value for 3D7MG-[DES]AZG and 3D7MG-[DES]AG were calculated 42.3 % and 58.6 %, respectively, while the control group exhibited a lower value of 37.8 %.

Environmentally stable, Adhesive, Self-healing, Stretchable and Transparent Gelatin based Eutectogels for Self-Powered Humidity Sensors

Intrinsic environmental and stability limitations of hydrogels have inhibited their practical applications as a flexible wearable device due to water evaporation or freezing in complex environments such as low temperatures and arid environments. In this work, a multifunctional gelatin based ionic conductive eutectogel with double network structure is designed via ternary deep eutectic solvent (DES) (acrylic acid (AA), choline chloride (ChCl) and ethylene glycol (EG)). In this system, the introduction of ethylene glycol (EG) can be used to dissolve gelatin. The resulting DESG eutectogel exhibited excellent adhesion, mechanical robustness, anti-freeze, anti-drying, and self-healing. Interestingly, the DESG gels showed high humidity sensitivity in a wide humidity detection range (11 %–83 %), which can be assembled as a self-powdered humidity sensor to monitor human mouth and nose breathing. This work is expected to bring new prospect to construct high performance humidity sensors using gelatin based humidity-responsive materials for a wide range of potential applications in respiratory diagnostics, sleep monitoring, electronic skin and wearable electronics.

Synergistic ternary deep eutectic solvents: An archetype for sustainable and eco-conscious Li and Co recovery from spent batteries

The development of sustainable materials for energy is a critical challenge in the pursuit of a circular economy. This study presents an innovative approach for recycling lithium-ion batteries (LIBs) using a novel, sustainable deep eutectic solvent (DES) composed of glycine, ascorbic acid, and water. This natural, chloride-free ternary DES leverages the biocompatible and eco-friendly properties of its constituents, achieving exceptional leaching efficiency of 99.1 % for lithium and 97.9 % for cobalt under optimized conditions. A multifaceted methodology integrating advanced factorial design, kinetic modeling, and machine learning was employed to refine the process parameters and enhance leaching efficiency. The extraction kinetics were predominantly governed by endothermic surface reactions, characterized by activation energies of 81.5 kJ/mol for Co and 110.9 kJ/mol for Li. An ensemble neural network model accurately predicted the extraction with an R2 > 0.95, demonstrating the robustness of the computational approach. The DES exhibited excellent recyclability over five cycles, thereby emphasizing its potential for practical industrial applications in the field of sustainable materials management. This approach facilitated the selective recovery of high-purity lithium oxalate and cobalt oxalate, underscoring the efficiency and environmental benefits of the process. DFT calculations provided insights into the extraction mechanism, revealing the crucial role of hydrogen bonding and synergistic effects of the DES components. This pioneering study not only advances LIB recycling but also establishes a comprehensive, quantitatively validated framework, paving the way for future innovations in sustainable materials management and supporting global efforts towards a circular economy in energy storage.

Fabrication of conductive composite hydrogels with excellent pressure sensitivity via in situ polymerization of ternary DES

In this paper, choline chloride, acrylamide and urea were used to prepare deep eutectic solvent (DES), and CS and N-CNTs were used as fillers to prepare composite hydrogels through in-situ polymerization. Using FTIR and SEM characterization analysis, the results showed that the pressure sensitivity and conductivity of the composite hydrogel were significantly improved after adding CS and N-CNTs. When the filler content reaches the highest level, the pressure sensitivity increases by 13 times and the conductivity reaches 2.05 mS/cm, which is 14.7 times that of the hydrogel without filler. This study provides a preparation method for composite hydrogels with excellent conductive properties and pressure sensitivity.

Recycled ionic liquid vs. deep eutectic solvent in cellulose nanocrystals production: Characterization, techno-economic analysis, and life cycle assessment

Three scenarios involving aqueous mixtures of neoteric solvents have been evaluated as solvents and catalysts for the cellulose hydrolysis reaction to obtain CNC in high yields (>70%). The scenarios considered were: scenario 1 (S1) involves a recyclable ionic liquid dilution of [Hmim][(HSO4)(H2SO4)]/H2O (64 wt% IL); scenario 2 (S2) another recyclable dilution of [Hmim][(HSO4)(H2SO4)]//H2O (80 wt% IL) and scenario 3 (S3) a non-recyclable ternary deep eutectic solvent (60 wt% DES: choline chloride: oxalic acid/30 wt% PA/10 wt% water). Experimental analysis, techno-economic, and life cycle analysis (LCA) indicate that S1 emerges as a suitable scenario among the three analyzed. S1 demonstrated the highest competitiveness, with a lower raw material cost per gram of CNC produced (US$0.81/g) and lower environmental contributions concerning climate change and fossil fuel depletion, accounting mainly for its recyclability. Therefore, the recyclable dilution of 64 wt% IL used in S1 appears to be the most viable option for sustainable and environmentally conscious CNC production. Besides, the physicochemical properties of the CNC were revealed: aspect ratio range 7–8, high dispersion stability related to zeta potential > −40 mV, good crystallinity range 50–80%, and thermal stability with Tonset> 300 °C. These results guided towards a scenario with crucial advantages: a diluted IL that retains its acidity after reuse cycles by a facile recovery process, maintaining high CNC production performance and providing low environmental impacts.

Recovery of Cobalt from Cathode of Lithium-Ion Battery Using Ternary Deep Eutectic Solvent

Recovery of Cobalt from Cathode of Lithium-Ion Battery Using Ternary Deep Eutectic Solvent

Green and rapid oxidation of aldehydes using a catalytic applications of Deep Eutectic Solvent

The development of novel and environmentally friendly solvents for chemical reactions is a vital in the pursuit of sustainable chemistry. This study presents a sustainable and efficient protocol for the rapid oxidation of benzaldehyde derivatives in the presence of catalytic Deep Eutectic Solvent (DES) system to their corresponding benzoic acids. A novel ternary DES composed of Urea/ZnCl2/HCl was synthesized using a combination of Urea, ZnCl2, and HCl for the first time and employed as an environmentally friendly oxidation catalyst using H2O2 as an oxidant at 60 °C. Benzaldehyde derivatives with diverse range of functional groups and substitution patterns afforded remarkable results, as it achieved high to excellent yields of the corresponding benzoic acids within a remarkably short reaction time of only 50 min. This protocol offers several advantages over alternative methods, including high product yields, the elimination of toxic and hazardous solvents and catalysts, and straightforward experimental procedures. Furthermore, the synthesized DES excellent recyclability, allowing for its reuse up to five times without any significant loss of functionality. Moreover, the synthesized DES demonstrated exceptional recyclability, enabling it to be reused up to five times without experiencing any notable decline in its effectiveness or functionality.

Novel ternary deep eutectic solvents used for recycling lithium and cobalt from waste lithium-ion batteries

The escalating disposal of lithium-ion batteries (LIBs) poses significant environmental challenges but also offers substantial opportunities for resource recovery. In this work, we introduce a recycling strategy using a green, cost-effective ternary deep eutectic solvent (DES) composed of guanidine hydrochloride, ethylene glycol, and maleic acid. The DES can achieve >99.5 % leach efficiency of lithium (Li) and cobalt (Co) at 100 °C, 9h, and L/S=50. The kinetic study found that the chemical reaction rate at the interface was the key to controlling the leaching process. The study of leaching mechanisms found that the acidity and coordination ability of DES were the main driving forces of leaching. Co loaded in the DES phase can almost precipitate out by using oxalic acid, achieving the separation of Li and Co. After reusing three times, the maximum load of Li in the DES phase reached 4.1 mg/g. These outstanding performances, along with the avoidance of the use of hazardous chemicals and the reduction of high costs, confirmed that the DES possesses a promising prospect for sustainable, large-scale application in efficiently leaching valuable metals from LiCoO2.

Novel ternary deep eutectic solvent fractionation for effective utilization of willow

A novel ternary deep eutectic solvent (TDES), consisting of zinc chloride, ethylene glycol and alpha hydroxy carboxylic acids (i.e., glycolic acid, citric acid and malic acid), was first proposed to effectively fractionate and convert willow (Salix matsudana cv. Zhuliu) into fermentable sugar. In particular, the zinc chloride/ethylene glycol/malic acid (ZnCl2/EG/MA) TDES system showed remarkable fractionation performance with 91.66 % xylan and 90.12 % lignin removals at 130 °C for 1.5 h, resulting in 96.01 % glucose yield in the subsequent enzymatic hydrolysis stage. Moreover, the regenerated lignin showed regular nanoparticle morphology and good antioxidant properties. Even after four recycling, the TDES showed 70.16 % of delignification and 83.70 % glucose yield with the TDES pretreated willow. Overall, this study demonstrated an effective solvent fractionation approach to maximize the utilization of total lignocellulose under mild conditions.

Simultaneous deep eutectic solvent based microextraction of Allura Red and Brilliant Blue in violet-purple foodstuffs

A vortex-assisted simultaneous deep eutectic solvent based microextraction and spectrophotometric determination method was established for the first time to simultaneously monitor Allura Red and Brilliant Blue in violet-purple foodstuffs. A ternary deep eutectic solvent was created using benzoic acid, tetra butyl ammonium bromide and benzyl alcohol at 1:1:3 mol ratio. The method variables including pH, volume of deep eutectic solvent and vortex time were optimized by Box-Behnken design of response surface methodology. The limits of detection were determined to be 25 and 9 µg/L for Allura Red and Brilliant Blue, respectively. The linear dynamic ranges of the method were obtained between 82 and 12,000 and 29–4200 µg/L for Allura Red and Brilliant Blue, respectively. Preconcentration factor of the method was obtained as 15. Greenness evaluation was performed using Analytical GREEnness tools. Extraction mechanisms affecting quantitative simultaneous microextraction of the target dyes were explained. The developed method was validated with high-performance liquid chromatography analysis. Analyte addition-recovery tests were also applied to confectionery samples to validate the proposed method and determine the dye contents of foodstuffs. Allura Red and Brilliant Blue contents of violet-purple confectioneries were determined between 3.85 and 74.59 and 4.02–26.11 µg/g concentrations with 94.5–98.6 % and 93.0–101.0 % recoveries, respectively.

A green and recyclable ternary deep eutectic solvent for extracting flavonol glycoside from Ginkgo leaves: Mechanism insights based on molecular level

A novel ternary deep eutectic solvent (DES) was designed for the green and efficient extraction of flavonol glycosides (FG) from Ginkgo leaves. The DES consisted of a molar ratio of choline chloride/acetic acid/1,2-propylene glycol of 1:2:3. The optimal extraction conditions were determined to a solid-liquid ratio of 42 mg/mL, an extraction time of 11.8 h, and an extraction temperature of 51℃. The extraction yield of FG was 7.8 mg/g, which demonstrated a notable enhancement in comparison to conventional extraction. Kinetics and morphology analysis revealed that the extraction process involved considerable dissolution and diffusion of the solute. Additionally, a molecular investigation using density functional theory (DFT) indicated that the interaction between the DES and FG was primarily governed by hydrogen bonding and van der Waals force. Notably, the ternary DES exhibited stronger interactions with FG, which were the key factors for better extraction efficiency. Furthermore, efficient recovery of FG from the DES solution was also achieved, with a recovery rate of 94.63%. Moreover, the recovered DES could be reused directly at least five cycles.

Experimental and dynamic molecular study of zinc extraction from sphalerite concentrate in ternary deep eutectic solvent

The utilization of deep eutectic solvents (DESs) as a novel class of solvents in metal production offers a promising alternative to aqueous solutions due to their biocompatibility and non-aqueous nature. This study investigated the leaching of sphalerite concentrate using a ternary stable DES composed of choline chloride (ChCl), p-toluene sulfonic acid (PTSA), and ethylene glycol (EG) (at a molar ratio of 1:1:1). The effects of time, temperature, and milling time on zinc recovery were examined within specific ranges (20–1440 min, 40–100 °C, and 0–24 h, respectively). The study revealed the significant influence of time and temperature on zinc dissolution efficiency within ChCl:PTSA:EG. Higher temperatures and longer leaching times were found to improve efficiency substantially. The research emphasized the crucial role of milling time, demonstrating that longer durations enhanced zinc efficiency by introducing more defects on the sphalerite surface and reducing particle size. Under optimized conditions, including a temperature of 100 °C, 24 h of ball milling, and 1440 min of leaching, a zinc recovery of 99.7% was achieved. Infrared analysis confirmed the chemical stability of the solvents during the leaching process. The sphalerite leaching process involved the formation of zinc chloride ion complexes and evolution H2S gas. An unexpected finding is the presence of lead sulfate in the leach residue, which may be attributed to sulfide oxidation to sulfate species. The Avrami kinetic model provided an excellent fit with the sphalerite dissolution data in ChCl:PTSA:EG DES, indicating that the rate-controlling step was primarily influenced by the diffusion process. R2 values for kinetics fitting data were in the range of 0.87–0.97 for temperature of 40–100 °C. The molecular dynamic (MD) simulation findings indicated robust electrostatic interactions between the metal ions Zn2+ and Fe2+ and the Cl− ions of the ChCl molecules. Additionally, the MD calculations showed that the metal ions formed complexes with some O-S-O atoms within the PTSA molecule.

Gel polymer electrolyte based on deep eutectic solvent in flexible Zn-air batteries enables dendrite-free Zn anode

Flexible Zn-air batteries (FZABs) are competitive candidates for wearable energy storage devices due to their high theoretical energy density, high safety and low cost. Various alkaline gel polymer electrolytes (GPEs) greatly reduce the operating time of the ZABs, which is prone to water loss and corrosion of the Zn anode. Therefore, one of the effective strategies is to prepare non-alkaline GPEs with excellent thermal stability. Herein, a novel acetamide (C2H5NO)/ZnCl2/H2O ternary deep eutectic solvent (DES) is developed. The GPE (named PAA-DES) is synthesized in one step by introducing PAA polymer network into DES, which is applied to FZABs. H2O in the solvated structure of Zn2+ is replaced by C2H5NO, and is controlled through hydrogen bonding. The obtained PAA-DES shows excellent tensile properties and electrolyte retention rate, and effectively inhibits dendrite growth of Zn anode. ZABs based on PAA-DES have good bending ability, which can operate for nearly 1000 h.

Efficient extraction of lignin from moso bamboo by microwave-assisted ternary deep eutectic solvent pretreatment for enhanced enzymatic hydrolysis

Applications of deep eutectic solvent (DES) systems to separate lignocellulosic components are of interest to develop environmentally friendly processes and achieve efficient utilization of biomass. To enhance the performance of a binary neutral DES (glycerol:guanidine hydrochloride), various Lewis acids (e.g., AlCl3·6H2O, FeCl3·6H2O, etc.) were introduced to synthesize a series of ternary DES systems; these were coupled with microwave heating and applied to moso bamboo. Among the ternary DES systems evaluated, the FeCl3-based DES effectively removed lignin (81.17%) and xylan (85.42%), significantly improving enzymatic digestibility of the residual glucan and xylan (90.15% and 99.51%, respectively). Furthermore, 50.74% of the lignin, with high purity and a well-preserved structure, was recovered. A recyclability experiment showed that the pretreatment performance of the FeCl3-based DES was still basically maintained after five cycles. Overall, the microwave-assisted ternary DES pretreatment approach proposed in this study appears to be a promising option for sustainable biorefinery operations.

Silver Recovery from E-Waste Printed Circuit Board Using Binary and Ternary Deep Eutectic Solvents

Printed Circuit Boards (PCBs) are essential components of electronic devices containing valuable silver metal. Using sustainable methods, silver recovery from electronic trash, like PCBs, demonstrates excellent promise. This research’s objective is to determine the optimum leaching time and solid-to-liquid (S/L) ratio for extracting silver from PCB using deep eutectic solvent (DES) composed of choline chloride and glycerol (glyceline DES). The binary DES’s leaching performance was then compared to choline chloride, glycerol, and citric acid ternary systems. Fourier Transform Infrared Spectroscopy (FTIR) was carried out to analyze the bond interactions. X-ray fluorescence spectrometry (XRF) was employed to determine the PCB’s metal concentration prior to and after the leaching process. Ternary DES was viscous, colorless, stable for 60 days, and less acidic than binary DES, with a 1.21 g/mL density. FTIR peak broadening and shifting indicated the formation of a new hydrogen bond and proved a successful synthesis of ternary DES. XRF result showed that PCB’s initial silver metal content was 2.32%. The optimal silver leaching from PCB using glyceline DES was achieved after 16 hours, with a 1/20 solid-to-liquid ratio. Ternary DES demonstrated a silver leaching efficiency of 93.65%, surpassing 86.77% of glyceline. Ternary DES synthesized in this study has the potential to serve as an efficient and environmentally friendly solvent for extracting silver from PCB, providing a sustainable approach to managing electronic waste.

Magnetic molecularly imprinted polymers using ternary deep eutectic solvent as novel functional monomer for hydroxytyrosol separation

In this work, magnetic molecularly imprinted polymers (MIPs) for specific recognition of Hydroxytyrosol (HT) were designed by vinyl-modified magnetic particles (Fe3O4@SiO2@VTEOs) as carrier, ternary deep eutectic solvent (DES) as functional monomer, while ethylene glycol dimethacrylate (EGDMA) as crosslinker. The optimum amount of DES was obtained by adsorption experiments (molar ratio, caffeic acid: choline chloride: formic acid = 1:6:3) which were 140 μL in total. Under the optimized amount of DES, the maximum adsorption capacity of the MIPs particles was 42.43 mg g−1, which was superior to non-imprinted polymer (4.64 mg g−1) and the imprinting factor (IF) is 9.10. Syringin and Oleuropicrin were used as two reference molecules to test the selectivity of the DES-MIPs particles. The adsorption capacity of HT was 40.11 mg g−1. Three repeated experiments show that the polymer has high stability and repeatability (RSD = 5.50).