Non-aqueous Media Research Articles

Direct photodegradation of aromatic carbamate pesticides: Kinetics and mechanisms in aqueous vs. non-aqueous media.

The direct photodegradation quantum yields (Φ) of five representative aromatic carbamate pesticides - carbaryl, carbofuran, propoxur, isoprocarb, and metolcarb - were examined in both aqueous and non-aqueous solutions, the latter mimicking hydrophobic environments such as leaf surfaces. For carbaryl, carbofuran, isoprocarb, and metolcarb, the Φ values generally followed the order Φwater < ΦMeOH < Φn-hexane, while propoxur showed a different trend, ΦMeOH < Φn-hexane < Φwater. Scavenging and laser flash photolysis experiments, combined with quantum chemical calculations, were used to clarify the photodegradation mechanisms. Photodegradation is primarily initiated by the singlet excited state (S*), with the triplet state (T * ) also contributing in compounds with conjugated structures, such as carbaryl. Upon excitation, methylcarbamate aromatic esters (MCAEs) generated both radical cations (S•+) and phenoxyl radicals (S-O•), and S•+ would convert to S-O• subsequently. S-O• is predominantly generated through the cleavage of C-O bonds in ester groups, subsequently abstracting hydrogen from solvent molecules. The reactivity of hydrogen donors in these solvents follows the order: -CH2- > -CH3 > -OH. For propoxur, the ether group also contributes to the formation of S-O•, which further reacts with H2O and enhances degradation in aqueous environments. Solvent polarity had a minimal effect on photodegradation. This comparative study of degradation in aqueous and nonaqueous phases provides insights for designing and selecting pesticides that are effective during use in nonaqueous environments, such as on leaf surfaces, yet degrade rapidly in aqueous environments in the post-application phase.

Comparative electrochemical study of oxidative nicarbazin determination in non-aqueous media: Differential pulse voltammetry vs. capillary electrophoresis with amperometric detection.

Electrochemistry offers a range of powerful techniques for solving analytical problems, each with its own advantages and limitations that can significantly affect the information obtained. These variations lead to diverse requirements for newly developed methods. Applying multiple electrochemical techniques simultaneously can optimize information extraction from a sample, aiding in the selection of the best analytical approach. In this study, we present the first investigation of the oxidation of the coccidiostat nicarbazin, along with a comparative evaluation of two established electrochemical methods with complementary strengths: differential pulse voltammetry (DPV) and capillary electrophoresis coupled with amperometric detection (CE-AD). We thoroughly examine the oxidative determination of nicarbazin in poultry feed samples using acetonitrile based media. DPV allows for rapid and efficient analysis, while CE-AD excels in handling complex samples with electrochemically active species due to its high separation efficiency. Both methods exhibit limits of detection (LODs) in the low micromolar range. To provide a comprehensive understanding of the nicarbazin oxidation process, the final reaction products were analyzed by mass spectrometry, identifying 4-nitroaniline and (4-nitrophenyl)formamide as key product compounds. This pioneering research on the anodic detection of nicarbazin includes a detailed analysis of the components in the studied equimolar mixture. The developed protocols, combined with straightforward sample preparation, enable the successful determination of nicarbazin levels below those allowed by EU regulations.

Thermodynamic Studies of Co(II) Complexation with Schiff Base Ligands in Different Nonaqueous Solvents

This study investigates the synthesis and characterization of two novel Schiff base ligands, L1 and L2, and their complexation behavior with Co(II) ions in non-aqueous media. Ligand L1 was synthesized using o-hydroxyacetophenone and salicylaldehyde with ethylenediamine, while L2 was prepared with 2,3-dihydroxybenzaldehyde and ethylenediamine. Conductometric measurements in ethanol, acetonitrile, and a 1:1 mixture of these solvents at temperatures ranging from 25°C to 40°C determined the stability constants of the Co(II) complexes. Results showed distinct temperature-dependent stability trends: L1 complexes decreased in stability with increasing temperature in all solvents, indicating exothermic reactions, while L2 complexes showed varied behavior, suggesting endothermic reactions in acetonitrile and the mixed solvent. The solvent environment significantly influenced complex stability, with acetonitrile showing the highest stability, followed by the 1:1 solvent mixture and ethanol. L2 exhibited higher stability constants than L1, attributed to additional hydroxyl groups in L2 enhancing Lewis basicity, while the methyl group in L1 caused steric hindrance, reducing stability. Thermodynamic analysis revealed negative ΔG° values (-27.9 to -32.1 kJ/mol) for all reactions, indicating spontaneity. Enthalpy changes (ΔH°) varied, with negative values (-27.6 to -195 kJ/mol) for exothermic and positive values (7.37 and 42.3 kJ/mol) for endothermic reactions. Entropy changes (ΔS°) varied, reflecting differences in molecular organization and solvent-ligand interactions. This study provides insights into factors affecting metal-ligand complexation in non-aqueous environments, with implications for designing coordination compounds for various applications in chemistry

Tunable Stabilization of Cuprous Ions via Kinetic and Thermodynamic Control of Cu Electrodeposition in Non-Aqueous Media.

In this work, significant stabilization of Cu+ ions is achieved in non-aqueous electrolytes containing TFSI- and Cl- anions with diglyme as solvent. When Cl- is absent, stabilization of Cu+ occurs due to the very low stability constant of Cu2+ in diglyme. However, in the presence of relatively low Cl- concentrations (i.e., equimolar relative to Cu2+), both Cu+ and Cu2+ form extremely stable Cu2+/+[Cl-] complexes resulting in a ∼1200 mV negative shift of the Cu+/0 redox couple relative to that of more easily reduced Cu+[TFSI-][Cl-] complexes. These results suggest that the lower solvation energies and wider electrochemical stability windows of non-aqueous solvents relative to water enable anions to play a much more significant role in guiding complexation behavior─providing new possibilities for (electro)chemical stabilization of reactive intermediates and highlighting the wealth of unexplored opportunities for electrolyte design in non-aqueous systems.

How non-aqueous media direct the reaction of Ca(OH)2 with CO2 to different forms of CaCO3: operando mid-infrared and X-ray absorption spectroscopy studies.

Time-resolved structural changes taking place during the reaction of Ca(OH)2 and CO2 forming different CaCO3 polymorphs, in aqueous and non-aqueous environments, were recorded operando using mid-infrared (mid-IR) and X-ray absorption near-edge structure (XANES) spectroscopy. Results show that Ca(OH)2 directly transforms into calcite in a pure water dispersion. In methanolic media with low water content, calcium di-methylcarbonate (Ca(OCOOCH3)2) is formed, which is hydrolysed to amorphous calcium carbonate (ACC) and vaterite in the presence of sufficient water. The addition of toluene shifts the equilibrium composition further from Ca(OH)2 to ACC and the crystalline forms of CaCO3, probably by affecting the activity of the methoxide intermediate. It can facilitate the formation of aragonite. No Ca(OH)2 conversion was detected in pure ethanol, isopropanol and toluene dispersions, except for nanoscale Ca(OH)2 in ethanolic dispersion, which formed calcium di-ethylcarbonate (Ca(OCOOCH2CH3)2). Our findings underline that vaterite formation is driven by the solution and solid state chemistry related to the reaction via alkoxides and carbonic acid esters of the alcohols, rather than the nucleation process in solution. The alcohol in these systems does not just act as a solvent but as a reactant.

Ag/Zn-Ta2C MXene composite as an efficient electrocatalyst for aqueous and non-aqueous CO2 reduction reactions

This study reports the preparation of an Ag and Zn-based Ta2CTx MXene composite and its electrocatalytic application towards the electrochemical CO2RR in aqueous and non-aqueous (organic) solvents. In aqueous 0.1 M KHCO3, Ag and Zn-based Ta2CTx MXene cathode enables efficient conversion of CO2 to valuable products such as syngas (CO:H2) and formic acid. Ag/Ta2CTx MXene-modified electrode, exhibiting the best CO and H2 (1:1) selectivity at an applied potential of − 0.65 V vs. RHE syngas, was collectively found to be ~ 80%, whereas at the same potential, some formate (20%) was formed. Similar to Zn/Ta2CTx, MXene showed the highest selectivity for CO of 83%. By employing a divided cell setup, CO2RR occurs at lower reduction potentials, enhancing the feasibility of the process. In non-aqueous media, styrene was electrocarboxylated to phenylsuccinic acid (PSA) and phenylpropanoic acid (PPA) using the same cathode, and the selectivity varies Ag/Ta2CTx MXene (45% of PSA) and Zn/Ta2CTx (41% of PPA) with respect to the metal ion present in the composite. Mono- and di-carboxylic acids were produced in quantifiable amounts using the MXene-modified electrodes as the cathode and sacrificial aluminum as the anode. This work highlights the potential of MXene-based electrocatalysts for aqueous CO2RR and selective electrocarboxylation, offering promising pathways for sustainable fuel production and chemical synthesis.Graphical

Additive Engineering of Water and “Water Mimic” in Lipase‐Catalyzed Aldol Reaction

AbstractThe additive approach is widely used to enhance enzymatic activity in nonaqueous media. In this study, both formamide, known as “water mimics”, and water, significantly enhanced the promiscuous aldol reaction activity of lipase from porcine pancreas. However, only water changed the stereoselectivity of the tested aldol reaction. Experimental and computational results revealed the different roles played by water and formamide. Compared with water, formamide exhibited different effects and acted as a cocatalyst to activate substrates rather than a “water mimic” to “loosen up” enzymes in anhydrous solvents.

Reaction of Nitrate Radicals and DMPO in Non-Aqueous Media: A Novel Detection Tool to Highlight the Nitrate Radical Role in Photocatalytic Processes.

The reaction of DMPO as the spin trapping agent with nitrate radicals photocatalytically generated results in the formation of DMPOX showing a highly specific EPR spectrum. The method can be used as a semi-quantitative and convenient way to detect nitrate radicals in non-aqueous solutions/suspensions, which was never achieved up to now through EPR spectroscopy. Results support in a more direct way the proposed generation and reactivity of nitrate radicals in photocatalytic media and open a new chapter in the field of heterogeneous photocatalysis.

Molecular combination between alkanolamines and galvinol for ratiometric colorimetric sensing of CO2 gas.

In this study, the application of alkanolamines as an optical CO2-responsive medium in combination with galvinol (GALH) as a reversible quantitative colorimetric sensor is proposed. Monoethanolamine (MEA) and diethanolamine (DEA), as the simplest primary (1°) and secondary (2°) alkanolamines, were explored for the colorimetric CO2 response attributed to their well-known CO2 absorption ability on an industrial scale from more than six decades. Further, the anionic form of GALH (GAL-) generates an intense purple color that allows its application for colorimetric measurement which has been very less explored for optical sensing purposes. A reversible, convenient, and simplified colorimetric detection of CO2 gas was performed using GALH in combination with MEA and DEA in CH3CN solvent, which showed limits of detection (LODs) for CO2 gas as low as ∼19 and ∼31 ppm respectively with recyclabilities. The main feature of the developed CO2 sensor is its non-aqueous medium application, which makes it ideal for producing error-free results under different humidity conditions.

Electrolyte jet machining of Zr-based amorphous alloys in non-aqueous medium with assistance of magnetic field

Zr-based amorphous alloys are innovative materials with promising applications, such as biological sectors and sports facilities. This study evaluates the effects of magnetic field assistance on electrolyte jet machining (EJM) of these alloys in alcohol-based electrolyte. Firstly, the electrochemical-induced interface structural evolution at different regions is examined to elucidate the dissolution mechanism of Zr-based amorphous alloys in the NaCl ethylene glycol electrolyte via atomic structural analysis. Then, based on the Cl¯ diffusion coefficients in the diffusion region and convection region of the inter-electrode gap calculated from the molecular dynamics (MD) simulation, the magnetic field is found to increase the total diffusion coefficient of Cl¯ in the diffusion and convection regions, improving the uniformity of the electrolyte and surface smoothness. Compared with a magnetic field parallel to the electric field, a perpendicular magnetic field has more improvement in machining performance. Furthermore, combined perpendicular and parallel magnetic fields of 0.1 T increase cavity depth by 47.91%, the MRR by 30.88%, and reduced surface roughness Ra from 0.364 to 0.298 μm, compared with the case without the magnetic field assistance. This research underscores the efficacy of magnetic field assistance in advancing the precision and sustainability of EJM for Zr-based amorphous alloys.

Prussian Blue Analogues Based on 3d-Metals as Cathode Materials for Magnesium Ion Batteries

Prussian blue PB analogues (K;Mg)xM[Fe(CN)6] were obtained via the co-precipitation method. Manganese, iron, cobalt, nickel, copper and zinc were selected to obtain the metal hexacyanoferrates (MHCFs) of these metals and to systematically study their structural and electrochemical properties as cathode materials. The obtained substances were characterized via X-ray powder analysis, scanning electron microscopy, thermogravimetric analysis and elemental analysis. An electrochemical study of the obtained cathode materials relative to a platinum anode in an aqueous medium and a magnesium anode in a nonaqueous medium was carried out, and the cycling parameters were determined. The influence of 3d-metal nature on the composition–structure–properties of hexacyanoferrates was demonstrated. MHCFs are promising cathode materials for Mg2+ intercalation/deintercalation in aqueous electrolytes.

Mechanism of cellulose staining in disperse dyeing of polyester/cotton blended fabrics in non-aqueous medium

Mechanism of cellulose staining in disperse dyeing of polyester/cotton blended fabrics in non-aqueous medium

Calcium Chemistry as A New Member of Post-Lithium Battery Family: What Can We Learn from Sodium and Magnesium Systems.

The development of next-generation battery technologies needs to consider their environmental impact throughout the whole cycle life, which has brought new chemistries based on earth-abundant elements into the spotlight. Rechargeable calcium batteries are such an emerging technology, which shows the potential to provide high cell voltage and high energy density close to lithium-ion batteries. Additionally, the use of Ca2+ as a charge carrier renders significant sustainable values. Although pioneering work on the electrochemistry of Ca has been carried out for more than half a century, demonstration of reversible Ca0/Ca2+ redox chemistry in non-aqueous media was only achieved within the past decade. In this review, we will present recent development of rechargeable calcium batteries, focusing on mainly the similarities but also differences between Ca chemistry and other post-lithium chemistry. According to the periodic nature of elements, magnesium (an alkaline earth element as Ca) and sodium (a diagonally adjacent element to Ca) have similar chemical properties to Ca in various aspects. We shall elaborate on how the solution chemistry, metal behaviors and transport mechanisms of Ca-ions can be better understood in light of the established principles in the respective Mg/Na systems. We hope the discussion will inspire synergetic development between Ca batteries and other post-lithium systems.

Influence of counterions on the thermal and solution properties of strong polyelectrolytes.

Strong polyelectrolytes (i.e., macromolecules whose charge density is independent of the medium's pH) are invaluable assets in the soft matter toolbox, as they can readily disperse in aqueous media, complex to oppositely charged species - polymers and small molecules alike - and can be implemented in a plethora of applications, ranging from surface modification to chelating agents and lubricants. However, the direct synthesis of strong polyelectrolytes in a controlled fashion remains a challenging endeavour, and their in-depth characterisation is often limited. Additionally, producing a set of charged macromolecules with the same chain length but varying counterions would open doors towards a fine control of the polymer's chemistry and physical properties. Unfortunately, this either necessitates the direct polymerisation of several monomers with potentially varying reactivities, or a time-consuming ion exchange from a single batch. Herein we explore the facile and efficient production of strong polyanions through the deprotection of a poly(3-isobutoxysulphopropyl methacrylate) using a range of inorganic and organic iodide-containing salts. Owing to the contrasting nature of their counterions, the resulting polyanions exhibit a wide range of glass transition temperatures, which follow a non-monotonic trend with increasing counterion size. While all polymers readily dissolve in water, some can also be dissolved in non-aqueous media as well. This strategy, applied to block copolymers, permits the production of a library of amphiphilic macromolecules with consistent hydrophilic and hydrophobic blocks, yet varying nature of their polyanionic segments. All amphiphiles, regardless of their counterions, readily disperse in aqueous media and form well-defined micelles featuring a hydrophobic core and a charged hydrophilic shell, as evidenced by dynamic light scattering, ζ-potential and transmission electron microscopy. Additionally, a handful of block copolymers are capable of yielding polymer micelles in organic solvents, opening an avenue to the build-up of nanostructured soft matter in non-aqueous media.

A comparative computational and scanning electrochemical microscopy study of factors influencing electron transfer at the hydrogenated and pristine graphite – propylene carbonate electrochemical interface

Through scanning electrochemical microscopy and computational simulation, we show that hydrogen functionalization on graphitic carbon electrodes increases electron transfer kinetics to redox-active species in non-aqueous media.

Constructing chelating organic macrocycles inside the pores of hybrid mesoporous silica to intensify the toxic metal recovery ability.

Inorganic-organic hybrid mesoporous silicas have been considered some of the most effective matrices for the adsorption of potentially toxic species from aqueous and non-aqueous media. Among them, SBA-15 porous silica is superior due to its all-connected large pores associated with the intrinsic high surface area of this class of materials. Herein, we take advantage of the high pore volume of SBA-15 and form large organic macrocycles containing basic centres inside the mesopores to potentialize the toxic metal adsorption ability from aqueous waste water. The construction of the macrocycles was carried out through controlled sequential reactions of the silica matrix with 3-iodopropyltriethoxysilane, diethyl iminodiacetate, cysteamine and 1,3-tribromopropane, resulting in a final chelating conformation containing nitrogen, oxygen and sulfur basic centres. The enclosed configuration intensified the complexing effect of the moieties and boosted the ability of toxic metal recovery from aqueous media. Especially for lead cation adsorption, the sequential functionalization led to uptake values of (1.09 ± 0.13), (2.96 ± 0.24), and (5.74 ± 0.07) mmol g-1 for diethyl iminodiacetate, cysteamine and macrocycle-containing hybrids, respectively. The maximum adsorption capacities of Cd2+ and Cu2+ were (0.12 ± 0.01) and (1.10 ± 0.07) mmol g-1, respectively. Calorimetric measurements provided further insight into the nature of the interactions of the metal cations with the pendant basic centres, indicating intensified adsorption effects according to the progress of the sequential modification processes.

On‐Demand Photochemical Modification of Glassy Carbon Surface

Chemical modification of carbonaceous materials is a convenient and reliable approach for the permanent fabrication of functional moieties. Among different linkers, diazirines offer a photogenerated reactive carbene that can insert into X–H (X; O, N) and add to π bonds to tether a variety of moieties on the surface of carbonaceous materials. Explicitly, 3‐phenyl‐3‐(trifluoromethyl)‐3H‐diazirine is more thermally and chemically stable within the diazirine family. Here, we synthesized 3‐(ferrocenylalkyloxy)‐3‐(trifluoromethyl)‐diazirine derivatives and utilized them to covalently modify the surface of glassy carbon (GC). The photogenerated carbene enabled the tethering of the ferrocene (Fc) to the surface of a GC electrode (GCE). The modified surface properties were investigated using different electrochemical techniques, ellipsometry spectroscopy, and scanning electron microscopy. Electrochemical surface responses in KCl and Ru(NH3)63+ solutions clearly exhibited ferrocene redox behavior and surface blocking during modification, respectively. Surface analysis results revealed a clear correlation between the thickness and capacitance current of the modified surface. More importantly, the obtained electrochemistry data show substantial chemical stability of the covalently tethered Fc on the GCE surface in both aqueous and nonaqueous media. The presented work offers an approach for the on‐demand photochemical formation of carbene from diazirines to add functionality for applications of modified electrodes in electrocatalysis and sensing.

Organic redox flow batteries in non-aqueous electrolyte solutions.

Redox flow batteries (RFBs) are gaining significant attention due to the growing demand for sustainable energy storage solutions. In contrast to conventional aqueous vanadium RFBs, which have a restricted voltage range resulting from the use of water and vanadium, the utilization of redox-active organic molecules (ROMs) as active materials broadens the range of applicable liquid media to include non-aqueous electrolyte solutions. The extended voltage range of non-aqueous media, exceeding 2 V, facilitates the establishment of high-energy storage systems. Additionally, considering the higher cost of non-aqueous solvents compared to water, the objective in developing non-aqueous electrolyte solution-based organic RFBs (NRFBs) is to efficiently install these systems in a compact manner and explore unique applications distinct from those associated with aqueous RFBs, which are typically deployed for grid-scale energy storage systems. This review presents recent research progress in ROMs, electrolytes, and membranes in NRFBs. Furthermore, we address the prevailing challenges that require revolution, encompassing a narrow cell voltage range, insufficient solubility, chemical instability, and the crossover of ROMs. Through this exploration, the review contributes to the understanding of the current landscape and potential advancements in NRFB technology and encourages researchers and professionals in the energy field to explore this emerging technology as a potential solution to global environmental challenges.

On‐Demand Photochemical Modification of Glassy Carbon Surface

Chemical modification of carbonaceous materials is a convenient and reliable approach for the permanent fabrication of functional moieties. Among different linkers, diazirines offer a photogenerated reactive carbene that can insert into X–H (X; O, N) and add to π bonds to tether a variety of moieties on the surface of carbonaceous materials. Explicitly, 3‐phenyl‐3‐(trifluoromethyl)‐3H‐diazirine is more thermally and chemically stable within the diazirine family. Here, we synthesized 3‐(ferrocenylalkyloxy)‐3‐(trifluoromethyl)‐diazirine derivatives and utilized them to covalently modify the surface of glassy carbon (GC). The photogenerated carbene enabled the tethering of the ferrocene (Fc) to the surface of a GC electrode (GCE). The modified surface properties were investigated using different electrochemical techniques, ellipsometry spectroscopy, and scanning electron microscopy. Electrochemical surface responses in KCl and Ru(NH3)63+ solutions clearly exhibited ferrocene redox behavior and surface blocking during modification, respectively. Surface analysis results revealed a clear correlation between the thickness and capacitance current of the modified surface. More importantly, the obtained electrochemistry data show substantial chemical stability of the covalently tethered Fc on the GCE surface in both aqueous and nonaqueous media. The presented work offers an approach for the on‐demand photochemical formation of carbene from diazirines to add functionality for applications of modified electrodes in electrocatalysis and sensing.

Rapid Naked-eye Detection of Fluoride Ions Using Near-infrared (NIR) Organic Dyes in Aqueous and Non-aqueous Medium

Rapid Naked-eye Detection of Fluoride Ions Using Near-infrared (NIR) Organic Dyes in Aqueous and Non-aqueous Medium