Deep eutectic solvents (DESs) were used as alternatives to the aqueous phase in solvent extraction of iron(
iii
), zinc(
ii
) and lead(
ii
). The selective extraction of iron(
iii
) and zinc(
ii
) ...was studied from a feed of ethaline (1 : 2 molar ratio of choline chloride : ethylene glycol) and lactiline (1 : 2 molar ratio of choline chloride : lactic acid), with the former DES being more selective. A commercial mixture of trialkylphosphine oxides (Cyanex 923, C923) diluted in an aliphatic diluent selectively extracted iron(
iii
) from a feed containing also zinc(
ii
) and lead(
ii
). The subsequent separation of zinc(
ii
) from lead(
ii
) was carried out using the basic extractant Aliquat 336 (A336). The equilibration time and the extractant concentration were optimized for both systems. Iron(
iii
) and zinc(
ii
) were stripped using 1.2 mol L
−1
oxalic acid and 0.5 mol L
−1
aqueous ammonia, respectively. An efficient solvometallurgical flowsheet is proposed for the separation and recovery of iron(
iii
), lead(
ii
) and zinc(
ii
) from ethaline using commercial extractants. Moreover, the process was upscaled in a countercurrent mixer-settler set-up resulting in successful separation and purification.
Deep eutectic solvents (DESs) were used as alternatives to the aqueous phase in solvent extraction of iron(
iii
), zinc(
ii
) and lead(
ii
).
This study has shown for the first time that digital holographic microscopy (DHM) can be used as a new analytical tool in analysis of kinetic mechanism and growth during electrolytic deposition ...processes. Unlike many alternative established electrochemical microscopy methods such as probe microscopy, DHM is both the noninvasive and noncontact, the unique holographic imaging allows the observations and measurement to be made remotely. DHM also provides interferometric resolution (nanometer vertical scale) with a very short acquisition time. It is a surface metrology technique that enables the retrieval of information about a 3D structure from the phase contrast of a single hologram acquired using a conventional digital camera. Here DHM has been applied to investigate directly the electro-crystallization of a metal on a substrate in real time (in situ) from two deep eutectic solvent (DES) systems based on mixture of choline chloride and either urea or ethylene glycol. We show, using electrochemical DHM that the nucleation and growth of silver deposits in these systems are quite distinct and influenced strongly by the hydrogen bond donor of the DES.
The effects of additives on the electrodeposition of ZnSn alloy from aqueous electrolyte have been the subject of considerable interest in the literature; however, to date there has been little ...consideration of their effects on alloy electrodeposition from Deep Eutectic Solvents (DESs). This work will show, for the first time, the effects of boric acid, ammonium chloride and nicotinic acid on the electrodeposition of ZnSn alloys on copper from a DES consisting of a stoichiometric 1:2 mix of choline chloride and ethylene glycol (Ethaline 200). Cyclic voltammetry has been used to study the electrochemical properties of the ZnSn electrolyte, and the resultant surface morphologies, composition and roughness of the ZnSn coating were revealed via SEM/EDX and AFM, demonstrating that boric acid and nicotinic acid function as very effective brighteners, producing highly uniform and smooth ZnSn deposits. It was found that these additives strongly affect the morphology, composition, and roughness of the ZnSn coating. XRD was also used to examine the crystal structure of ZnSn coatings, where it was found that the phase composition of the deposits depends on the additive(s) used. In addition, corrosion of the ZnSn alloy in salty media was measured using the Tafel method.
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•Electrodeposition of ZnSn alloys from DES bath containing additives was investigated.•The additives brighten the ZnSn deposit because of double layer changes.•The effect of various additives on morphology and structure of ZnSn from DES were studied.•The corrosion behaviour of ZnSn coating decreased by the addition NH4Cl additive in DES.
Despite the importance of ionic liquids in a variety of fields, little is understood about the behaviour of protons in these media. The main difficulty arises due to the unknown activity of protons ...in non-aqueous solvents. This study presents acid dissociation constants for nine organic acids in deep eutectic solvents (DESs) using standard pH indicator solutes. The p
K
In
value for bromophenol blue was found by titrating the DES with triflic acid. The experimental method was developed to understand the acid-base properties of deep eutectic solvents, and through this study it was found that the organic acids studied were slightly less dissociated in the DES than in water with p
K
a
values between 0.2 and 0.5 higher. p
K
In
values were also determined for two ionic liquids, BmimBF
4
and Emimacetate. The anion of the ionic liquid changes the pH of the solution by acting as a buffer. Emimacetate was found to be more basic than water. It is also shown that water significantly affects the pH of ionic liquids. This is thought to arise because aqueous mixtures with ionic liquids form heterogeneous solutions and the proton partitions into the aqueous phase. This study also attempted to develop an electrochemical pH sensor. It was shown that a linear response of cell potential
vs.
ln
a
H
+
could be obtained but the slope for the correlation was less than that obtained in aqueous solutions. Finally it was shown that the liquid junction potential between two reference electrodes immersed in different DESs was dependent upon the pH difference between the liquids.
Relative pH values are calculated using an indicator dye and a glass electrode, and they are found to provide consistent results.
We demonstrate the first practical alternative to the use of phosphoric and sulphuric acid mixtures for the electropolishing of stainless steel. In this paper, efficient electropolishing of type 316 ...stainless steel is demonstrated in an ionic liquid composed of ethylene glycol (HOCH
2CH
2OH) and choline chloride (HOC
2H
4N(CH
3)
3
+Cl
−). Linear sweep voltammetry, chronoamperometry, scanning electron microscopy, atomic force microscopy and AC impedance methods were used to investigate the steel dissolution mechanism and the results are compared to polishing done in aqueous acidic solutions. It is shown that the quality of the polish is related to the breakdown of the oxide film and preliminary data suggest that the polishing process may be controlled by the diffusion of chloride ions. The dissolution is different from that found in aqueous acid solutions, and oxide breakdown is shown to be slower, which can lead to pitting at low current densities.
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•Electrodeposition of Cu from DES bath containing nicotinic acid (NA) was investigated.•A bright Cu coating was produced from a deep eutectic solvent bath containing NA.•Nicotinic ...acid affected the Cu electrochemical behaviour in the deep eutectic solvent.•Surface characterisation of Cu coatings was modified by the addition of NA.
The use of additives to modulate metal electrodeposition from deep eutectic solvents has, to date, apparently been of little interest given the dearth of such studies in the literature. Here, we have actively investigated the effects of nicotinic acid (NA) on the electrodeposition of copper in a choline chloride (ChCl)-ethylene glycol (EG)-based deep eutectic solvent (DES), (1ChCl:2EG), considered a “green solvent” due to its physiochemical properties. Bright copper deposits were formed when NA was added to the Cu electrolyte, while a dull Cu deposit was produced in its absence. New Cu species were found to have formed in the 1ChCl:2EG-based liquid when NA was added to the electrolyte. A number of analytical techniques, in this instance cyclic voltammetry, chronoamperometry, and chronocoulometery, have been employed to determine the various electrochemical properties, nucleation mechanisms, and kinetics of the Cu species reported herein. The diffusion coefficient for the Ethaline-Cu system was found to be affected by the concentration of NA. An electrochemical quartz crystal microbalance (EQCM) was used to monitor the current efficiency of the copper deposition in both systems. The morphologies, thicknesses, roughnesses, and crystal structures of the copper electrodeposited from the NA-modified electrolyte were characterised via scanning electron microscopy (SEM), atomic force microscopy (AFM), and X-ray diffraction (XRD), which between them demonstrate that the NA introduced into this system acts as a highly effective brightener, producing highly uniform and smooth copper deposits.
Here we demonstrate the generation of novel ionic liquid analogue (ILA) electrolytes for aluminium (Al) electrodeposition that are based on salts of amidine Lewis bases. The electrolytes exhibit ...reversible voltammetric plating/stripping of Al, good ionic conductivities (10–14 mS cm−1), and relatively low viscosities (50–80 cP). The rheological properties are an improvement on analogous amide-based ILAs and make these liquids credible alternatives to ILAs based on urea or acetamide, or conventional chloroaluminate ionic liquids (IL) for Al battery applications.
Developing new functionalities of two-dimensional materials (2Dms) can be achieved by their chemical modification with a broad spectrum of molecules. This functionalization is commonly studied by ...using spectroscopies such as Raman, IR, or XPS, but the detection limit is a common problem. In addition, these methods lack detailed spatial resolution and cannot provide information about the homogeneity of the coating. Atomic force microscopy (AFM), on the other hand, allows the study of 2Dms on the nanoscale with excellent lateral resolution. AFM has been extensively used for topographic analysis; however, it is also a powerful tool for evaluating other properties far beyond topography such as mechanical ones. Therefore, herein, we show how AFM adhesion mapping of transition metal chalcogenide 2Dms (i.e., MnPS3 and MoS2) permits a close inspection of the surface chemical properties. Moreover, the analysis of adhesion as relative values allows a simple and robust strategy to distinguish between bare and functionalized layers and significantly improves the reproducibility between measurements. Remarkably, it is also confirmed by statistical analysis that adhesion values do not depend on the thickness of the layers, proving that they are related only to the most superficial part of the materials. In addition, we have implemented an unsupervised classification method using k-means clustering, an artificial intelligence-based algorithm, to automatically classify samples based on adhesion values. These results demonstrate the potential of simple adhesion AFM measurements to inspect the chemical nature of 2Dms and may have implications for the broad scientific community working in the field.
Cyclometallated phenyls with substituents para to the metal have a larger impact on the redox potentials and emission of complexes Ir(R-ppz)(2)(bipy)PF(6) than substituents at the meta position and ...hence enable tuning of emission wavelength over a wider range using the same substituent.
Electroactive films based on conducting polymers have numerous potential applications, but practical devices frequently require a combination of properties not met by a single component. This has ...prompted an extension to composite materials, notably those in which particulates are immobilised within a polymer film. Irrespective of the polymer and the intended application, film wetting is important: by various means, it facilitates transport processes - of electronic charge, charge-balancing counter ions ("dopant") and analyte/reactant molecules - and motion of polymer segments. While film solvent content and transfer have been widely studied for pristine polymer films exposed to molecular solvents, extension to non-conventional solvents (such as ionic liquids) or to composite films has been given much less attention. Here we consider such cases based on polyaniline films. We explore two factors, the nature of the electrolyte (solvent and film-permeating ions) and the effect of introducing particulate species into the film. In the first instance, we compare film behaviours when exposed to a conventional protic solvent (water) with an aprotic ionic liquid (Ethaline) and the intermediate case of a protic ionic liquid (Oxaline). Secondly, we explore the effect of inclusion of physically diverse particulates: multi-walled carbon nanotubes, graphite or molybdenum dioxide. We use electrochemistry to control and monitor the film redox state and change therein, and acoustic wave measurements to diagnose rheologically
vs.
gravimetrically determined response. The outcomes provide insights of relevance to future practical applications, including charge/discharge rates and cycle life for energy storage devices, "salt" transfer in water purification technologies, and the extent of film "memory" of previous environments when sequentially exposed to different media.
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