Room Temperature Dissolution Research Articles

Rapid Dissolution of Gold in Alcohols by In-Situ Generation of Halogens.

The dissolution of elemental gold is a fundamental step in its recycling by hydrometallurgy but has a significant environmental impact due to the use of strong acids or highly toxic reagents. Herein, it is shown that mixtures of acetyl halides and hydrogen peroxide in alcohols promote the rapid room-temperature dissolution of gold by halogenation to form Au(III) metalates. After leaching, distillation of the alcohol and re-dissolution in dilute HCl, the gold was refined through its precipitation by a simple diamide ligand; this method was also applied to separate gold from a mixture of metals. The leaching process is rapid, avoids the use of highly toxic materials and corrosive acids, and can be integrated into selective separation processes, so has the potential to be used in the purification of gold from ores, spent catalysts, and electronic and nano-waste.

Glycosidic bond protection of cellulose during solvent dissolution by coordination interaction competition strategy

Exploiting new solvents on efficiently dissolving cellulose is imperative to promote the utilization of cellulosic resources. The process of cellulose dissolution typically necessitates extreme conditions, such as high-temperature treatment, utilization of potent acidic or basic solvents, or the catalytic action of Lewis acids. As a result, the structure of the cellulose is invariably compromised, subsequently obstructing the creation of high-performance materials. In this study, we address this challenge through a simple process, introducing polyethylene glycol (PEG) as glycosidic bond protecting agent, to preserve the polymerization degree of cellulose during its room-temperature dissolution in ZnCl2-phosporic acid eutectic solvent. The PEG units preferentially coordinate with Zn2+ to weaken the hydrolysis of glycosidic bond of cellulose through ether bond competition. The polymerization degree of regenerated cellulose is thus greatly improved, reaching up to seven times that of unprotected cellulose. Overall, this study offers an easy and cost-effective approach to develop cellulose solvents and provides a significant drive towards the fabrication of practical materials through cellulose dissolution.

Combining 3D Printing and Electrochemical Deposition for Manufacturing Tailor-Made 3D Nickel Foams with Highly Competitive Porosity and Specific Surface Area Density

One of the most promising and heavily researched energy storage systems due to their high energy density, rate capability and extended cycle life are lithium-ion batteries. Their performance and efficiency are nonetheless strongly dependent on their constituent materials and design, including the current collectors. One attractive approach in this respect is the use of metal foams as an alternative to the conventional current collectors. This concept is therefore intended to increase the current collectors’ specific surface area and therefore load more active material by nominal area while keeping the cell architectures simple and less costly. In the present work, nickel is chosen as a model system for a proof of concept of a novel manufacturing method for nickel foams using a combination of 3D printing, coating and electroplating. The purpose is to create geometrically well-defined hollow structures with high porosity and specific surface area density that can rival and partially outperform the commercially available nickel foams. To this end, a 3D printer is used to create geometrically flexible and well-defined open-pored disks of HIPS (high-impact polystyrene), which are then spray coated with a graphite-based conducting layer and subsequently electroplated with a 5–30 µm thin layer of nickel from an additive-free nickel sulfamate electrolyte. Following the coating process, the support structure is dissolved with toluene, resulting in structures with a unique combination of porosity in the range of 92.3–99.1% and an ultra-high specific surface area density up to 46 m2/kg. Morphological characterization by light and scanning electron microscopy has proven that the temporarily required polymer substrate can be mildly and completely removed by the suggested room temperature dissolution process.

A room temperature dissolution solvent and its mechanism for natural biopolymers: hydrogen bonding interaction investigation

Hydrogen bonds (HBs) are vital construction fundamentals of natural biopolymers.

Rapid, selective, and room temperature dissolution of crystalline xylan by a hydrotrope

Selective dissolution of industrial biowaste is of significant importance for the valorization of biomass. Especially, fractionation of polysaccharides with similar structures is more challenging. Herein, a new kind of cationic hydrotrope, tetraethylammonium hydroxide (TEAH), has been developed for rapid, efficient, and selective dissolution of industrial biowastes-xylan type hemicelluloses from viscose fiber mills. When the concentration of TEAH is 15 wt%, the solubility of industrial crystalline xylan reaches to 13.39 wt% at room temperature. Crystalline or amorphous xylan can be regenerated by adding water or ethanol, with 57.98 % and 95.45 % yields, respectively. Additionally, we showcase hemicelluloses were near-completely extracted from holocellulose without degrading cellulose under ambient temperature by simply adjusting the concentration of TEAH, demonstrating the advantage of the hydrotropic feature. This hydrotrope solvent system features selective, rapid, and room temperature dissolution polysaccharides, which will shed new light in technological applications of the industrial spinning or biorefining processes.

Fabrication of cellulose cryogel beads via room temperature dissolution in onium hydroxides

In recent years, there has been a growing interest in green solvents to dissolve and shape cellulose into microspheres. However, development of solvents suitable for room temperature dissolution and shaping of cellulose spheres is very limited. In this work, a novel process to fabricate cellulose microspheres is presented. First, the effect of ethanol-hydrochloric acid pulp pretreatment on cellulose solubility in aqueous tetra-n‑butyl phosphonium hydroxide and tetra-n‑butyl ammonium was investigated. While the dissolution of untreated pulp remained limited to 5 wt%, the pretreatment boosted pulp solubility to 15 wt%. Spherical beads were obtained via dropwise addition of the solution in ethanol. Cryogels beads with a BET surface area of 218.1 m²/g were collected when using 90 v% tert‑butyl alcohol as the freeze-drying medium. After gathering the spent ethanol and initial washing of the beads, 90.7% of the tetra-n‑butyl phosphonium hydroxide solution was recovered and successfully reused to prepare a subsequent batch of beads. The proposed bead preparation system further fits within the concept of topochemical design as beads could be fabricated from low to high cellulose concentrations, regardless of temperature, therefore offering great opportunities to design gels for different applications such as drug delivery systems, protein conjugation or wastewater treatment.

Hydrogen bond reconstruction strategy for eutectic solvents that realizes room-temperature dissolution of cellulose

Based on a hydrogen-bond reconstruction strategy, a new solvent was designed to realize the efficient dissolution of cellulose at room temperature.

Room-temperature dissolution of PbI2 by a PEGylated deep eutectic solvent with high efficiency

PEGylated deep eutectic solvents could dissolve toxic PbI2 efficiently at room temperature.

Room temperature dissolving cellulose with a metal salt hydrate-based deep eutectic solvent

Abundant and renewable cellulose is a potential candidate for petroleum-derived synthetic polymers. However, the efficient dissolution of this material is problematic because of the high cost, severe reaction condition (e.g., high temperature) and environmentally unfriendly (e.g., toxic reagents, and solvent recyclability). Herein, to realize the room temperature dissolution of cellulose with an inexpensive and eco-friendly solvent, we design a novel low-cost deep eutectic solvent that is composed of zinc chloride, water and phosphoric acid for the efficient dissolution of cellulose. This solvent is featured as having both the superior hydrogen bonding acidity and the hydrogen bonding basicity, and thus can act as a hydrogen bond molecular scissors to cleave the hydrogen bonds within cellulose. In this process, microcrystalline cellulose can be easily dissolved in the solvent at room temperature with a dissolution ratio up to 15 wt%. The dissolved cellulose can also be recovered without any derivatization. The universality, recyclability and pilot production of dissolving cellulose using this solvent are also demonstrated. This work provides a new strategy for the design of novel deep eutectic solvent capable of disrupting the hydrogen bonds of cellulose under mild conditions.

Room-temperature dissolution and chemical modification of cellulose in aqueous tetraethylammonium hydroxide\u2013carbamide solutions

The room-temperature dissolution of cellulose in aqueous tetraethylammonium hydroxide (TEAOH) in the presence of carbamides (ureas) was investigated. Without carbamide, 35 wt% TEAOH was able to dissolve cellulose (microcrystalline cellulose) up to 3 wt%, whereas carbamides—such as urea, N-methylurea, N-ethylurea, 1,3-dimethylurea, and imidazolidone—were able to improve the dissolution of cellulose. At 5 wt% cellulose concentration, the highest carbamide contents in the solvent still able to dissolve cellulose within 1 h were 56 and 55 wt% of 1,3-dimethylurea and N-methylurea, respectively. When using urea, up to 15% of cellulose could be dissolved in a solution containing 22 wt% of urea. To demonstrate the possibility of the use of a carbamide-based solvent in cellulose modification, cationic cellulose was produced using glycidyltrimethylammonium chloride (GTAC). At a molar ratio of 1:3 of cellulose and GTAC, all the studied TEAOH–carbamide solvents produce cationic cellulose with higher charge density compared to the reference NaOH–urea solvent.

Fabrication of regenerated cellulose nanoparticles by mechanical disintegration of cellulose after dissolution and regeneration from a deep eutectic solvent

Regenerated cellulose nanoparticles were produced by mechanical disintegration of regenerated cellulose obtained from room temperature dissolution in a deep eutectic solvent.

Room Temperature Dissolution of Bulk Elemental Ni and Se for Solution Deposition of a NiSe2 HER Electrocatalyst.

With hydrogen fuel becoming a more viable alternative to fossil fuels comes the need for inexpensive, low-energy hydrogen production. Here, a low-temperature direct solution-processing method is presented for the deposition of earth-abundant pyrite-type NiSe2 as an efficient hydrogen evolution reaction (HER) catalyst. Thin films of phase-pure NiSe2 are deposited from a precursor ink prepared by room-temperature dissolution of bulk elemental Ni and Se in a binary thiolamine solvent mixture. The nanostructured NiSe2 thin films demonstrate high HER catalytic activity with 100% Faradaic efficiency.

Dissolution of antibiotics mycelium in ionic liquids: Performance and mechanism

Abstract Antibiotics mycelium, byproduct of pharmaceutical industry, contains high percentage of proteins, polysaccharides and lipids, while, the low solubility in traditional solvents limits its utilization. The dissolution process of penicillin mycelium was investigated using ionic liquids (ILs) as solvent. Quantitative correlation of solubility and ILs structure and dissolution mechanism were determined. About 91.45% of penicillin mycelium was dissolved in 1-butyl-3-methylimidazolium acetate ([Bmim]Ac) under the condition of 120.0 °C and [Bmim]Ac/mycelium (m/m) ratio of 3.90:1. Synergistic effect of ILs and DMSO was confirmed with the DMSO/[Bmim]Ac (v/m) ratio in the range of 0.0–1.0. At 25.0 °C, the dissolution of penicillin mycelium increased from 69.74% to 94.50%, with the ratio of DMSO to [Bmim]Ac (v/m) as 1:1. The room temperature dissolution of mycelium provides a novel and energy-saving process for its high-valued utilization. The NMR and FT-IR spectra showed that hydrogen bonds are the dominant driving force for the dissolution in ILs. Quantitative study on the effects of anions and cations of ILs on dissolution using Kamlet–Taft model showed that there was a linearly positive correlation between solubility of penicillin mycelium and β parameter of the ILs. The solubility of mycelium increased with increasing hydrogen bond accepting ability of anions and donating ability of cations.

Room temperature dissolution of cellulose in tetra-butylammonium hydroxide aqueous solvent through adjustment of solvent amphiphilicity

The amphiphilicity of solvent systems is realized for adjusting the dissolution of natural cellulose by making use of tetra-butylammonium hydroxide (TBAH) as an example. TBAH aqueous solution is found to have an obvious effect on adjusting its amphiphilicity, along with a flexible concentration ranging from 40 to 60 wt% for dissolving cellulose. With a suitable amphiphilic property, cellulose can be dissolved by a TBAH aqueous system . The experimental results demonstrate that with the introduction of urea (more than 0.2:1, w:v) into a TBAH aqueous system, the dissolution process of cellulose can be dramatically promoted, leading to a transparent solution of cellulose. Herein, a complex solvent of TBAH/urea has been proposed for mild and effective dissolution of cellulose under ambient conditions. In the TBAH/urea complex solvent, the structure of the hybrid hydrate of TBAH and urea formed. Urea served as a hydrophobic contributor adjusting the amphiphilicity of the solvent system, allowing interfacial resistance between the amphiphilic crystal surfaces of the natural cellulose and solvent to be reduced. After that, the crystal of natural cellulose could be fully infiltrated and subsequently dissolved by the TBAH/urea aqueous solvent. The performances of the aqueous solvent and ambient temperature dissolution make aqueous TBAH/urea a potential and green solvent of cellulose for broad applications, such as composites, films or wet spinning of cellulose, in laboratories or industries.

The properties and structure of zinc magnesium phosphate glasses

Zn–Mg-phosphate (ZMP) glasses, including those with the nominal molar compositions (50−x)ZnO xMgO 50P2O5 (0≥x≥50) and (60−y)ZnO yMgO 40P2O5(0≥y≥60), were prepared and properties such as density, refractive index, coefficient of thermal expansion and glass transition temperature (Tg), were measured. The glass transition temperature increases by 100–150°C and the room temperature dissolution rates in water decrease by 1–2 orders of magnitude when MgO replaces ZnO while maintaining a constant P2O5 content. Glass structures were characterized by Raman spectroscopy and there were no significant changes in the phosphate anion distributions when MgO replaces ZnO. The significant changes in properties cannot be explained by a simple cation field strength argument since Mg2+ and Zn2+ have similar sizes; instead, the effect of 3d electrons on the nature of the bonds between Zn2+ ions and non-bridging oxygens on the phosphate tetrahedra must be considered.

Structural characterization of methanol substituted lanthanum halides

The first study into the alcohol solvation of lanthanum halide [LaX 3] derivatives as a means to lower the processing temperature for the production of the LaBr 3 scintillators was undertaken using methanol (MeOH). Initially the de-hydration of {[La(μ-Br)(H 2O) 7](Br) 2} 2 ( 1) was investigated through the simple room temperature dissolution of 1 in MeOH. The mixed solvate monomeric [La(H 2O) 7(MeOH) 2](Br) 3 ( 2) compound was isolated where the La metal center retains its original 9-coordination through the binding of two additional MeOH solvents but necessitates the transfer of the innersphere Br to the outersphere. In an attempt to in situ dry the reaction mixture of 1 in MeOH over CaH 2, crystals of [Ca(MeOH) 6](Br) 2 ( 3) were isolated. Compound 1 dissolved in MeOH at reflux temperatures led to the isolation of an unusual arrangement identified as the salt derivative {[LaBr 2.75·5.25(MeOH)] +0.25 [LaBr 3.25·4.75(MeOH)] −0.25} ( 4). The fully substituted species was ultimately isolated through the dissolution of dried LaBr 3 in MeOH forming the 8-coordinated [LaBr 3(MeOH) 5] ( 5) complex. It was determined that the concentration of the crystallization solution directed the structure isolated ( 4 concentrated; 5 dilute) The other LaX 3 derivatives were isolated as [(MeOH) 4(Cl) 2La(μ-Cl)] 2 ( 6) and [La(MeOH) 9](I) 3·MeOH ( 7). Beryllium Dome XRD analysis indicated that the bulk material for 5 appear to have multiple solvated species, 6 is consistent with the single crystal, and 7 was too broad to elucidate structural aspects. Multinuclear NMR ( 139La) indicated that these compounds do not retain their structure in MeOD. TGA/DTA data revealed that the de-solvation temperatures of the MeOH derivatives 4– 6 were slightly higher in comparison to their hydrated counterparts.

Formation of Interfacial Voids in Aluminum by Room-Temperature Dissolution

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Development of a model for the anodic behavior of T60 titanium in chlorinated and oxygenated aqueous media. Application to the specific conditions of hydrothermal oxidation (1 MPa

This work evaluates the anodic electrochemical behavior of titanium metal in hydrothermal oxidation conditions (up to 400 °C and 28 MPa) in chlorinated media in order to estimate the supercritical water oxidation reactors reliability for the treatment of less than 10% organic-waste waters. The titanium room temperature dissolution mechanism in chlorinated acidic medium (pH<0) is not fundamentally modified by oxygen. Deduced from the ‘current–potential’ and ‘valence–potential’ curves, it is based on four crucial elementary steps leading to two branches: a so-called active branch corresponding to a trivalent dissolution (its effect is inversely proportional to the pH), and a passive branch (TiO 2 oxide formation with a very limited tetravalent dissolution). In hydrothermal oxidation (pH>1), only the second branch is effective. The titanium protection is directly related to the oxide stability in high pH systems. The mechanism model is expressed in terms of ‘current–potential’ laws, which provide kinetic parameters using optimization calculations. The different elementary steps reaction rates were estimated as well as the evolution of the reaction intermediates coverage ratios with the potential. The quantification of each elementary step was performed to understand and/or orient the materials behavior according to different factors (pH, chloride ions contents, potentials…).

Room temperature dissolution of metal powders by thiourea: a novel route to transition metal isothiocyanate complexes

A new synthetic route to isothiocyanate containing materials is presented. Five isothiocyanate 4-methylpyridine (γ-picoline) compounds were prepared by refluxing metal powders (Fe, Co, Ni and Cu) with thiourea in γ-picoline. The isothiocyanate ligand is generated in situ by the isomerization of thiourea to NH 4 +SCN − at reflux temperatures. The complexes [Fe(NCS) 2(pic) 4]·pic ( 1), [Co(NCS) 2(pic) 4]·pic ( 2), [Ni(NCS) 2(pic) 4] ( 3), [Cu(NCS) 2(pic) 4]·2/3pic·1/3H 2O ( 4), [Cu(NCS)(pic) 2] x ( 5) (where pic=γ-picoline) were characterized by X-ray crystallography; the structural data for compounds 1– 3 and 5 are presented.

Spontaneous dissolution at room temperature of gold nanoparticles.

We have studied gold nanoparticles evaporated on NaCl. We examined the sample before and after an annealing at room temperature for seven months. We found that most of the small particles with square shape disappear after the annealing. Many of the particles remaining correspond to multiple twinned particles (MTP), i.e., particles with icosahedral or decahedral shapes. We also found that the size of the icosahedral and decahedral particles did not change with the room-temperature annealing. The only consistent explanation is a spontaneous dissolution of the square-shaped nanoparticles at room temperature. This indicates that the binding energy of the atoms in such particles is much lower than the bulk value. The reason why such a particle would rather be dissolved instead of undergoing quasimelting is not clear. Room-temperature dissolution of square-shaped particles is another example of nanoparticles instability.