Choline Chloride-urea Deep Eutectic Solvent Research Articles

Decarboxylation of Hydroxybenzoic Acids to Phenol via Deep Eutectic Solvents.

The development of greener and more sustainable synthesis processes for manufacturing commodity chemicals is of great importance. The majority of current phenol production methods involve harsh reaction conditions with high energy consumption, causing severe environmental pollution. In this study, we present a novel approach for the decarboxylation of hydroxybenzoic acids (HBAs) to phenol using a choline chloride-urea (ChCl-urea) deep eutectic solvent (DES). Our study reveals the remarkable dual performance of ChCl-urea both as a catalyst and solvent for the decarboxylation of HBA, resulting in a high phenol yield (94 mol%) under mild reaction conditions. The proposed reaction pathway, established through a combination of experiments and computational simulations, enhances our understanding of this process. The recyclability of the DES system during decarboxylation was also assessed. Our findings demonstrate that the integration of DES into conventional chemical processes can pave the way for sustainable manufacturing, exemplifying a novel approach for producing phenol from abundant natural resources using designer solvents.

On the"Staple" Effect in the d-Glucose Acetylation by Choline-Chloride Ethylene Glycol and Choline-Chloride Urea Deep Eutectic Solvents.

This work employs hybrid quantum mechanics molecular mechanics simulations coupled with an umbrella sampling technique to investigate the acetylation of d-glucose with acetic anhydride in two deep eutectic solvents (DESs): choline-chloride ethylene glycol (ChCl/Etg) and choline-chloride urea (ChCl/U). The reaction proceeds spontaneously, with activation free energy barriers of 18.19 ± 0.15 and 19.83 ± 0.15 kcal/mol for ChCl/Etg and ChCl/U, respectively. These values align with literature data for similar reactions in ionic liquids, highlighting the potential of DESs as green reaction media for wood modifications, while minimizing lignocellulosic matrix degradation. Energy pair distribution analysis, radial distribution functions, and noncovalent interactions reveal a more solvated transition state compared to the initial reactant state within ChCl/Etg, facilitating the acetylation reaction. Interestingly, combined distribution function analysis unveils a "staple" effect in both solvents, potentially hindering efficient product separation. The work further explores hydrogen bond networks and Kamlet-Taft solvatochromic parameters to elucidate the role of solvents in the reaction mechanism. It was observed that a notable decrease in activation energy is accompanied by increasing net basicity, along with a reduction in the "staple" effect. This suggests that solvent parameters could serve as an effective screening tool for identifying novel and efficient DESs for wood modifications.

The Antisolvent Precipitation of CuZnOx Mixed Oxide Materials Using a Choline Chloride-Urea Deep Eutectic Solvent.

Metal oxides have applications in a variety of different fields, and new synthesis methods are needed to control their properties and improve their performance as functional materials. In this study, we investigated a low-cost antisolvent precipitation method using a choline chloride-urea deep eutectic solvent to precipitate CuZnOx materials using water as the antisolvent. Using this methodology, the metal oxide materials can be precipitated directly from the deep eutectic solvent without the need for a high-temperature calcination step that can lead to a reduction in defects and surface area, which are important properties in applications such as catalysis.

Effect of lignin in cellulose nanofibers on biodegradation and seed germination

AbstractPure cellulose nanofibers (CNFs) rapidly degrade in soil, limiting their prospective applications in agriculture. We incorporated lignin into CNFs as an antimicrobial and crosslinking agent to control the biodegradation rate. CNFs with different lignin concentrations were prepared by mechanochemical treatment in the presence of choline chloride-urea deep eutectic solvent. These were characterized using conductometric titration, scanning electron microscopy, and FT-IR. The fibers were applied to soil to determine the effect of lignin on soil respiration and nanocellulose degradation, and were used as a substrate for radish and cress seed germination. Modifying the lignin content of the fibers successfully modulated the biodegradation rate in soil. Fibers containing 35% lignin degraded 5.7% in 14 days, while fibers with 20% lignin degraded 20.8% in 14 days. Nanofiber suspensions showed low chemical inhibition for the germination of radish and cress seeds but higher lignin contents reduced the imbibition rate as a seed coating. This study presents the first use of lignin to control the biodegradation rate of cellulose nanofibers in a one-pot, scalable and sustainable system, allowing the advancement of lignocellulose nanofibers for applications such as seed coatings, mulches, and controlled release fertilizers. Graphical Abstract

Innovative deep eutectic solvent approaches in zinc electroplating for morphology enhancement, superior strength, and corrosion protection

The growing number of galvanized scrap due to the extensive application of galvanized products has led to a significant increase of the zinc content in the electric furnace dust, so how to realize high-value comprehensive utilization of zinc-containing dust has become a key issue for the sustainable development of the iron and steel industry. Based on the principle of recycling zinc resources, this study proposes an innovative full life cycle process for the preparation of electro-galvanized sheet using zinc-containing dust as raw material and deep eutectic solvents (DESs) as medium. Zinc plating was successfully prepared on duplex steel automobile plates using choline chloride-urea DES (Reline) as the electrolyte, and the modifying effects of different concentrations of nicotinic acid (NA) on the electrochemical system of the solution and the prepared plating were also investigated. The results show that the addition of 0.06 M NA to the system can modulate the deposition morphology of the plating layer, leading to the generation of ultrafine grains, and the surface densities and flatness are significantly improved. Besides, the addition of NA to the system increased the hardness value by 67.5 % and reduced the coefficient of friction by 38.8 % compared to the plating obtained in the system without additives; the corrosion rate decreased from 0.374 mm·a-1 to 0.023 mm·a-1, and the corrosion mechanism of the zinc layer was a direct dissolution process of zinc. This study realizes the morphology regulation of electroplated zinc plating, and greatly improves the aesthetics, mechanical properties and corrosion resistance of the plating at the same time, also the preparation process is in line with the requirements of the green development, which can provide a novel solution for the automotive high-quality plating.

Polyvinylpyrrolidone-mediated synthesis of ultra-stable gold nanoparticles in a nonaqueous choline chloride–urea deep eutectic solvent

This study investigates the role of polyvinylpyrrolidone (PVP) as a capping and stabilizing agent for the synthesis of gold nanoparticles (AuNPs) in a nonaqueous choline chloride–urea deep eutectic solvent (DES).

Correction: Polyvinylpyrrolidone-mediated synthesis of ultra-stable gold nanoparticles in a nonaqueous choline chloride–urea deep eutectic solvent

Correction for ‘Polyvinylpyrrolidone-mediated synthesis of ultra-stable gold nanoparticles in a nonaqueous choline chloride–urea deep eutectic solvent’ by Raúl Ortega-Córdova et al., RSC Appl. Interfaces, 2024, 1, 600–611, https://doi.org/10.1039/D3LF00261F.

Green and sustainable devulcanization of ground tire rubber using choline chloride–urea deep eutectic solvent

The reduction of time and energy consumption of existing green recycling methods while increasing the amount of production output.

New insight into highly efficient CSA@g-C3 N4 for photocatalytic oxidation of benzyl alcohol and thioanisole: NAEDS as a promoter of photoactivity under blue LED irradiation.

An open new perspective has been established toward synthesizing eco-friendly CSA@g-C3 N4 employing surface engineering. The carbon nitride modified through camphorsulfonic acid was designed and developed in a category of the new generation of photocatalysts for the oxidation of benzyl alcohol and thioanisole in the existence of a natural deep eutectic solvent (NADES). In comparison with pure g-C3 N4 , not only does CSA@g-C3 N4 exhibit an extraordinarily higher ability for harvesting visible light stemming from declining the recombination rate of electrons/holes dependent on PL results but it also reveals notable photocatalytic oxidation capability in the transformation of alcohols as well as thiols into relevant compounds. In addition, non-metal compound (CSA) incorporation would result in considerably diminishing the energy band gap value from 2.8 to 2.28 eV to escalate the visible-light absorption of g-C3 N4 . While the conventional consensus implies that inherent properties of photocatalysts bring on high photoactivity, this study indicates that deploying choline chloride-urea deep eutectic solvent as an external factor plays the role of photoactivity accelerator. Furthermore, readily recycling and reusability can be achieved for the photocatalytic setup of CSA@g-C3 N4 ascribed to its heterogeneous nature with no drop in the photoactivity.

Ionothermal synthesis of activated carbon from waste pet bottles for dye waste water treatment

The production and use of poly-ethylene terephthalate (PET) bottles in packaging have increased significantly. Thus, PET bottles have become a significant plastic waste with environmental problems. Currently, the conventional methods for producing activated carbons (ACs) from waste PET are unsustainable, complex, and unfeasible. As a result, ionothermal synthesis (IS) of waste PET bottles impregnated with choline chloride-urea (CU) deep eutectic solvent (DES) was carried out in order to prepare ACs. The obtained ACs were characterized using XRD, CHNS Elemental analysis and FTIR. The as-prepared ACs were effective as adsorbents for dye adsorption from dye waste water. Specifically, the AC obtained from pristine waste PET bottles (956 mgg−1 at 100 ppm) displayed higher adsorptive capacity compared to the ACs obtained from CU-DES impregnated PET flakes (550mgg−1 at 100ppm). Even though it was expected that the use of CU-DES required no post-synthesis washing or higher temperature treatments might be required to improve the adsorptive capacity of the ACs obtained from IS.This research work established that the synthesis of AC from abundant waste PET bottles using a sustainable and facile method could facilitate its commercial application. Also, this work represents the first attempt to produce activated carbons from PET using low temperature annealing in the presence of limited air, instead of the usual pyrolysis.

Urea–choline chloride deep eutectic solvent-assisted synthesis of luminescent nitrogen-doped carbon dots from chitin and their photocatalytic application in decolourizing malachite green

Luminescent carbon dots (CDs) are emerging carbon nanomaterials whose tunable and exceptional optoelectronic properties have found applications as alternatives to traditional fluorophores and metal-based catalysts. Further, they can be easily prepared from biomass and using green solvents. Biomass sources of CDs, however, often result in the formation of thousands of products, which are difficult to separate. In this study, CDs were synthesized using a urea–choline chloride deep eutectic solvent and shrimp shell-derived chitin as raw materials through a low-temperature solvothermal treatment. This was followed by a facile liquid–liquid extraction with acetone to improve the optical properties and narrow the size distribution of the CDs. The acetone-extracted CDs (ACDs) showed good performance in photocatalytic degradation of the aquatic pollutant, malachite green. They also show good potential in monitoring various toxic water pollutants through the quenching effect of selected pesticides, antibiotics, heavy metals, and anions on the fluorescence of ACDs.

Electrochemical formation and stability of copper selenide thin films in the choline chloride-urea deep eutectic solvent at gold electrode

The electrodeposition of copper-selenium binary compounds on gold electrode was investigated in the choline chloride – urea (ChCl-U) deep eutectic solvent at 110 °C. Cyclic voltammetry and potentiostatic deposition followed by stripping voltammetries were employed to gain thermodynamic insights pointing to the formation of Cu2Se, which is supported by X-Ray Photoelectron Spectroscopy. The electrochemical stability domain of the compound is about 900 mV (from ≈−0.81 V to ≈+0.07 V vs. a silver quasi-reference electrode) and is consistent with the thermodynamics of induced co-deposition. The domain is limited at positive potentials by the oxidation to Se(0) and at negative potentials by the reduction to Cu(0). While copper is readily deposited on the gold electrode, the electrodeposition of selenium requires a significant overpotential. As a consequence, copper is kinetically favoured in the co-deposition and is present in its pure form at short deposition times. This is circumvented by using longer deposition times or more negative potentials. Photoelectrochemical measurements show that the as-deposited compound behaves as a p-type semiconductor.

Valorizing waste PET bottles into Li-ion battery anodes using ionothermal carbonization

Waste poly(ethylene terephthalate) (PET) bottles (WPBs) are fast becoming an environmental nuisance, and their valorization to carbon anodes could be a sustainable method to manage this waste and also develop cheap and high-performance carbon materials for lithium (Li)-ion batteries (LIBs). Carbonaceous materials derived from WPBs were prepared using an ionothermal carbonization (ITC) method in a choline chloride–urea deep eutectic solvent system. The ITC-derived materials were subsequently annealed in air to obtain carbonaceous materials. The ITC-derived carbon displayed ultra-high nitrogen doping but less carbonization and graphitic ordering compared with the equivalent carbon material obtained using hydrothermal carbonization (HTC). Therefore, higher-temperature annealing/pyrolysis was recommended for the ITC-derived carbon. The HTC-derived carbon was investigated as an anode material for an LIB with promising electrochemical performance. The LIB displayed a stable reversible capacity of about 130 mAh/g at a current density of 0.1 A/g after 20 cycles and an increasing coulombic efficiency that reached 98% after the 50th cycle. This work shows that a facile and sustainable synthesis method can be used to produce PET-derived activated carbon with potential applications in energy-storage systems such as LIBs.

Data related to the article "Ion Correlation in Choline Chloride-Urea Deep Eutectic Solvent (Reline) from Polarizable Molecular Dynamics Simulations"

Data related to the article "Ion Correlation in Choline Chloride-Urea Deep Eutectic Solvent (Reline) from Polarizable Molecular Dynamics Simulations"

Role of embedding choline chloride-urea deep eutectic solvent on biomass-derived porous activated carbon in its capacitive deionization performance

Capacitive deionization (CDI) is a propitious desalination technique for medium and large-scale applications. The CDI cell performance is primarily controlled by the electrode material characteristic. Beyond the classic electro-sorption phenomenon, assistive separation mechanisms may be incorporated through the surface functionality of the electrode technology to build on the salt removal efficiency of the CDI system. Herein, we report on the impact of modifying biomass-derived porous activated carbon (AC-FB) electrodes with a hydrophilic deep eutectic solvent (DES), such as choline chloride-urea (ChCl-U) to introduce extra ion-dipole interaction sites through its rich hydrogen bonding network. The HR-transmission electron microscopy evidences the presence of DES on the sample surface. The thermogravimetric analysis and water contact angle measurements were done on the AC-FB and AC-FB-DES electrode to confirm the successful embedding of DES into the activated carbon (AC). In this symmetric configuration, the Na+ and Cl− ions are accommodated by the modified layer at the AC-FB-DES electrode. The electrochemical properties of the electrode were analyzed using CV and EIS analysis. The AC-FB-DES showed an 85% enhancement of removal percent compared to the plain AC-FB at 1.2 V in a 600 mg L−1 NaCl solution, despite that it shows a 40% drop in the specific capacitance compared to that of the AC-FB at a scan rate of 10 mV s−1. It is believed that upon applying potential, the rearrangement in the layered structure of urea–choline chloride at the electrified interface of the AC-FB electrode provides electro-induced active sites which enhance both CDI kinetics and overall ions removal. It is also believed that embedding DES on the AC-FB enhances the electro-adsorption performance of the AC by modifying the electrical double layer structure at the interfaces by introducing extra intermolecular interactions and surface polarization that play a synergistic role in the salt removal process.

Recycling of zinc oxide dust using ChCl-urea deep eutectic solvent with nitrilotriacetic acid as complexing agents

The leaching of zinc from zinc oxide dust was investigated in choline chloride-urea deep eutectic solvent (ChCl-urea DES) with the addition of nitrilotriacetic acid (NTA). The effect of important parameters on leaching process, such as leaching temperature, leaching time, liquid/solid ratio and NTA concentration was investigated and the optimization was done using surface response methodology (RSM) based on central composite design (CCD). The optimum condition for leaching of zinc from zinc oxide dust was identified to be a leaching temperature of 79.0 °C, a leaching time of 35.4 h, a liquid/solid ratio of 12.1 and an NTA concentration of 0.07 mol/L. A maximum of 87.9% of zinc was recovered under the optimum experimental conditions. The leaching process is controlled by diffusion and the corresponding activation energy is 26.2 kJ/mol. The resultant leaching solution was directly used for the electrodeposition of zinc, and pure zinc deposit is obtained.

Electrochemical immunosensor for determination of cardiac troponin I using two-dimensional metal-organic framework/Fe3O4–COOH nanosheet composites loaded with thionine and pCTAB/DES modified electrode

Cardiac troponin-I (CTnI) is one of the most popular biomarkers which can be utilized for the diagnosis and control of acute myocardial infarction in clinical practice. Here, a sandwich-type electrochemical immunosensor has been established using the zinc-based metal-organic framework/Fe3O4–COOH/thionine labeled anti-CTnI monoclonal antibody (Ab1-Zn-MOF/Fe3O4–COOH/Thi) nanocomposite as signaling molecule and a polymer film of cetyltrimethylammonium bromide (pCTAB) in the presence of choline chloride-urea deep eutectic solvent (DES) and anti-CTnI polyclonal antibody (Ab2) as immobilization substance of detecting surface. The porous ultrathin layers of Zn-MOF nanosheets successfully prepare a well-defined structure for Fe3O4–COOH electrocatalyst and Thi within a certain two dimensional (2D) regions, which enhances electrochemical reduction of Thi. The Ab1-Zn-MOF/Fe3O4–COOH/Thi nanocomposites were introduced to CTnI in the specimen and on the surface of pCTAB/DES-Au-SPE quantitative determination of CTnI was achieved using differential pulse voltammetry after sandwiching the CTnI target between Ab1-nanocomposite and Ab2 which was encapsulated into the pCTAB/DES-Au-SPE. This immunosensor indicated the appropriate assay performance for CTnI with the detection range of 0.04 ng mL−1 to 50 ng mL−1 and the limit of detection of 0.0009 ng mL−1. This study provides convenient plan for sensitive detection of bioanalytes and opens a path for the establishment of user-friendly and cost-effective device.

Properties and Kinetics of Selective Zinc Leaching with Choline Chloride and Urea

A choline chloride-urea (ChCl-urea) deep eutectic solvent (DES) was used to experimentally investigate the secondary recovery of zinc from zinc-bearing dust sludge via a leaching process. The effects of varying the liquid–solid ratio, leaching temperature, stirring speed, and leaching time on the zinc leaching efficiency were determined, and the optimum values of these parameters were found to be 15:1, 90 °C, 400 rpm, and 600 min, respectively, at which a leaching efficiency of 86.87% was achieved. XRF and EDS analyses confirmed that the zinc content in the sludge decreased noticeably after leaching, while those of other elements did not, indicating the selective and efficient leaching of zinc. A study of the leaching kinetics showed that the reaction conforms to the nuclear shrinkage model without solid product layer formation, and the calculated apparent activation energy is 22.16 kJ/mol.

Electrochemical Behavior and Electronucleation of Copper Nanoparticles from CuCl2·2H2O Using a Choline Chloride-Urea Eutectic Mixture

This work presents a thorough study on the early stage of copper electrodeposition from a choline chloride-urea deep eutectic solvent (DES). Determination of possible species in DES containing Cu2+ ions as the electrolytes has been performed using UV-Vis measurements. Kinetic and thermodynamic aspects of copper electrodeposition on glassy carbon electrode from DES were thoroughly investigated using cyclic voltammetry (CV) and chronoamperometry (CA). Both results from CA and CV have demonstrated that the copper electrodeposition could be performed directly from DES containing a small amount of water by the single potentiostatic step technique. Theoretical approach confirmed that the direct electronucleation of copper nanoparticles in the DES can be described by a model with two contributions, namely, (i) adsorption process and (ii) a three-dimensional (3D) nucleation and diffusion-controlled growth of copper nuclei, to the total current density transients. Kinetic parameters are important for controlling morphology and chemical composition of the obtained nanoparticles, which are verified by surface characterization techniques such as SEM and EDS.

Polyimide ultrafiltration membrane embedded with reline-functionalized nanosilica for the remediation of pharmaceuticals in water

This study introduces the use of choline chloride-urea (ChCl-U) deep eutectic solvent (DES) in polyimide (PI) ultrafiltration (UF) membranes to enhance the filtration removal of aqueous pharmaceuticals such as ibuprofen and paracetamol. The DES is immobilized over silica nanofiller particles by impregnation, and the composite ChCl-U@SiO2 is embedded at different loadings in the preparation of the PI UF membrane case solutions. The effects of ChCl-U@SiO2 loading on the resulting surface roughness, porosity, average pore size, hydrophilicity, and mechanical properties of the membranes were evaluated and correlated with the UF performance. The modified membrane was assessed using dead-end vacuum filtration experiments to measure the water permeate flux, solution permeate flux, and removal efficiency for 50 ppm paracetamol and 50 ppm ibuprofen from synthetic aqueous mixtures. The results showed that a 2 wt% ChCl-U@SiO2 nanofiller loading was necessary to produce membranes with the optimal aforementioned performance characteristics. The ChCl-U@SiO2 (2 wt%) PI UF membrane showed a significant increase in the water flux (250 L/m2 h) compared to the pristine membrane (30 L/m2 h), due to the enhancement of the hydrophilic character of the membrane. The large water flux was accompanied by an outstanding removal efficiency of up to 99.9% for paracetamol, exceeding that of the bare PI membrane (15%) by ~ 6 folds. The rejection removal of ibuprofen (87%) was roughly 7.9 times greater than that for the pristine membrane. This study provided substantial insights for the potential application of DES as a green modifier in the membrane-based removal of pharmaceutical pollutants from water.