Showing papers on "Solvent published in 2018"
TL;DR: In this article, the effect of different operating parameters (i.e. solvent concentration, temperature, time and solid/liquid ratio) were further evaluated to determine the optimal extraction conditions for polyphenols recovery in terms of total phenolic content (TPC) and antioxidant activity based on DPPH radical scavenging method.
250 citations
TL;DR: An amino functionalized boron nitride (FBN) based filtration membrane with a nanochannel network for molecular separation and permeation and shows high transport performance for solvents depending on the membranes’ thickness is reported.
Abstract: Pressure-driven, superfast organic solvent filtration membranes have significant practical applications. An excellent filtration membrane should exhibit high selectivity and permeation in aqueous and organic solvents to meet increasing industrial demand. Here, we report an amino functionalized boron nitride (FBN) based filtration membrane with a nanochannel network for molecular separation and permeation. This membrane is highly stable in water and in several organic solvents and shows high transport performance for solvents depending on the membranes' thickness. In addition, the FBN membrane is applicable for solute screening in water as well as in organic solvents. More importantly, the FBN membranes are very stable in acidic, alkaline and oxidative media for up to one month. The fast-flow rate and good separation performance of the FBN membranes can be attributed to their stable networks of nanochannels and thin laminar structure, which provide the membranes with beneficial properties for practical separation and purification processes.
229 citations
TL;DR: In this article, an eco-friendly and practical protocol for the synthesis of Z-vinyl thiocyanates through ultrasound-promoted Bronsted acid ionic liquid-catalyzed hydrothiocyclic synthesis of activated alkynes under minimal solvent conditions has been developed.
193 citations
TL;DR: In this paper, the authors discuss some recent advances in the preparation of novel solid acids with controllable wettability and suitable hydrophobicity and highlight their application in catalyzing various reactions such as esterification and esterization.
Abstract: Acid catalysts are widely used in petrochemical reactions, the synthesis of fine chemicals, and biomass conversions in industry. To comply with the principles of green and sustainable chemistry, much attention is being paid to the replacement of traditional liquid acids with solid acid catalysts. Normally, solid acids exhibit hydrophilicity because of the unique hydrophilic nature of the acidic sites on their surfaces. Water, as a typical solvent, byproduct, or negative component in a variety of acid-catalyzed reactions, may be adsorbed on solid acids and then cause the deactivation of catalytic sites or hydrolysis of the frameworks. The development of solid acids with suitable hydrophobicity largely overcomes these issues and enhances their catalytic activities and reusability. This Review discusses some recent advances in the preparation of novel solid acids with controllable wettability and suitable hydrophobicity and highlights their application in catalyzing various reactions such as esterification, ...
180 citations
TL;DR: In this paper, a review focusing on various perovskite formation and crystallization routes with respect to processing parameters including the precursor solvent, solvent mixture, temperature, time, formation of solvent led intermediate complex species, doping and humidity are discussed.
Abstract: An organic–inorganic perovskite is comprised of an organic cation (CH3NH3+, FAI, or Cs), a metal cation (Pb2+ or Sn2+) and a halide (I−, Cl−, or Br−) molecule. Precursor salts containing these cations, molecules and halide ions dissolved in solvents are used to prepare perovskite films. Perovskite film formation takes place through the reaction of precursor elements, which is assisted by various processing conditions such as thermal annealing, moisture and solvent treatment. This review focuses on various perovskite formation and crystallization routes with respect to processing parameters including the precursor solvent, solvent mixture, temperature, time, formation of solvent led-intermediate complex species, doping and humidity. Adding water as the dopant to the precursor solvent and exposure to moisture from atmospheric humidity to improve perovskite film quality are also discussed. Processing conditions and crystallization processes are described in correlation with the perovskite film morphology, crystallinity, defects, charge transport and device performance. This article will aim to highlighting recent findings in the selection of solvents in the crystallization of perovskite films, solvent induced intermediate phases, and effects of water in assisting perovskite crystallization for improved film quality and device performance. The review will also present various structural and nanoscale characterization techniques that have been used to probe solvent based intermediate species transformation processes to the perovskite phase and understand the effects in correlation with device performance.
180 citations
TL;DR: The chemical composition of AKEO revealed that oleic acid is the major fatty acid present in AKEO and N-methyl-2-pyrrolidone (NMP) is present in a significant quantity as discussed by the authors.
179 citations
TL;DR: In this paper, a solution-processed CsPbI2Br perovskite has attracted more and more attention in the field of photovoltaic application.
174 citations
01 Mar 2018
TL;DR: In this article, the authors investigated the effects of organic solvent mixtures with water on the kinetics of acid-catalysed dehydration reactions of relevance to biomass conversion, and demonstrated that the understanding of these solvation effects can be employed to optimize the rate and selectivity for production of the biomass platform molecule hydroxymethylfurfural from fructose.
Abstract: The use of organic solvents in biomass conversion reactions can lead to high rates and improved selectivities. Here, we elucidate the effects of organic solvent mixtures with water on the kinetics of acid-catalysed dehydration reactions of relevance to biomass conversion. Based on results from reaction kinetics studies, combined with classical and ab initio molecular dynamics simulations, we show that the rates of acid-catalysed reactions in the liquid phase can be enhanced by altering the extents of solvation of the initial and transition states of these catalytic processes. The extent of these effects increases as the number of vicinal hydroxyl or oxygen-containing groups in the reactant increases, moving from an alcohol (butanol), to a diol (1,2-propanediol), to a carbohydrate (fructose). We demonstrate that the understanding of these solvation effects can be employed to optimize the rate and selectivity for production of the biomass platform molecule hydroxymethylfurfural from fructose.
166 citations
TL;DR: In this article, the authors investigate the solidification of MAPbI3 films in situ during spin/blade-coating using optical and X-ray scattering methods, and find that the coating method and conditions profoundly influence the crystallization process, which proceeds through intermediate crystalline solvates.
Abstract: Blade-coating has recently emerged as a scalable fabrication method for hybrid perovskite solar cells, but it currently underperforms spin-coating, yielding a power conversion efficiency (PCE) of ∼15% for CH3NH3PbI3 (MAPbI3). We investigate the solidification of MAPbI3 films in situ during spin/blade-coating using optical and X-ray scattering methods. We find that the coating method and conditions profoundly influence the crystallization process, which proceeds through intermediate crystalline solvates. The polymorphism and composition of the solvates are mediated by the solvent removal rate dictated by the process temperature in blade-coating. Low to intermediate temperatures (25–80 °C) yield solvates with differing compositions and yield poor PCEs (∼5–8%) and a large spread (±2.5%). The intermediate solvates are not observed at elevated temperatures (>100 °C), pointing to direct crystallization of the perovskite from the sol–gel ink. These conditions yield large and compact spherulitic domains of perovs...
153 citations
TL;DR: In this article, a review on performances of water, alcohols and other hydrogen donor solvents in liquefaction of biomass has been made, and the yield of hydrogen donated in the reaction has also been reported.
Abstract: The environmental impact of global warming, caused by greenhouse gases has also fuelled the needs to utilise biomass, as its energy utilisation creates less environmental pollution and fewer health risks than fossil fuel combustion. Liquefaction of biomass using hydrogen donor solvents is a promising route to obtain clean biofuel using various solvents at moderate to high temperature (250–460 °C) and pressure (150–320 bar). Solvents such as sub-and supercritical water, alcohol, decalin, glycerol and tetralin can be used as potential hydrogen donor to enhance liquid oil yield with a reduced of oxygen content. Supercritical water with its excellent transport properties as well as hydrogen donor capability leads to hydrothermal decomposition of biomass and enhancing various compounds depending upon operating parameters. The selection of alcohol as a solvent related to the action of hydrogen donor and to its alkylating ability. The hydrogen donor solvents provide an alternative to hydrogen gas as a reducing gas. The advantage of using hydrogen donor solvent is to stabilise the free radical in the biomass liquefaction and yielding a higher product conversion. Compared with non-hydrogen donor solvents, hydrogen donor solvents such as tetralin and decalin show significant improvement not only in conversion and product distribution to liquid but also on the quality of bio-oil (oxygen content) due to the improvement of hydrogenation and hydrocracking reactions with inhibition of polycondensation. The advantage of hydrogen donor solvents over the molecular hydrogen due to a lower strength bonding of C-H as compared to H-H bond. A review on performances of water, alcohols and other hydrogen donor solvents in liquefaction of biomass has been made. The yield of hydrogen donated in the reaction has also been reported.
138 citations
TL;DR: Combined experimental and theoretical assessments of these solvent effects unveil that it is the hydrogen donating ability of the solvents that governs the hydrogenation rate of the reactants, while strong dissociative adsorption of the alcohol solvent on Mo-based catalysts results in surface decoration which controls the reaction selectivity.
Abstract: Selective activation of chemical bonds in multifunctional oxygenates on solid catalysts is a crucial challenge for sustainable biomass upgrading. Molybdenum carbides and nitrides preferentially activate C═O and C-OH bonds over C═C and C-C bonds in liquid-phase hydrogenation of bioderived furfural, leading to highly selective formations of furfuryl alcohol (FA) and its subsequent hydrogenolysis product (2-methyl furan (2-MF)). We demonstrate that pure-phase α-MoC is more active than β-Mo2C and γ-Mo2N for catalyzing furfural hydrogenation, and the hydrogenation selectivity on these catalysts can be conveniently manipulated by alcohol solvents without significant changes in reaction rates (e.g., > 90% yields of FA in methanol solvent and of 2-MF in 2-butanol solvent at 423 K). Combined experimental and theoretical assessments of these solvent effects unveil that it is the hydrogen donating ability of the solvents that governs the hydrogenation rate of the reactants, while strong dissociative adsorption of the alcohol solvent on Mo-based catalysts results in surface decoration which controls the reaction selectivity via enforcing steric hindrance on the formation of relevant transient states. Such solvent-induced surface modification of Mo-based catalysts provides a compelling strategy for highly selective hydrodeoxygenation processes of biomass feedstocks.
TL;DR: The method was successfully applied to determination of curcumin in food and herbal tea samples and the mean recoveries were between 96% and 102% and standard deviations were found in the range of 1-6%.
TL;DR: This magnetically responsive superhydrophobic surface not only provides a novel interface for microfluidic control and droplet transportation, but also opens up new avenues for achieving smart liquid-repellent skin, programmable fluid collection and transport, and smart microfluidity devices.
Abstract: A smart, magnetically responsive superhydrophobic surface was facilely prepared by combining spray coating and magnetic-field-directed self-assembly. The surface comprised a dense array of magnetorheological elastomer micropillars (MREMPs). Benefitting from the magnetic field-stiffening effect of the MREMPs, the surface exhibited reversible switching of the wettability and adhesion that was responsive to an on/off magnetic field. The wettability and adhesion properties of the surfaces with MREMPs were investigated under different magnetic fields. The results revealed that the adhesion force and sliding behaviors of these surfaces were strongly dependent on the intensity of the applied magnetic field and the mixing ratio of poly(dimethylsiloxane) (PDMS), iron particles, and solvent (in solution) used for preparation of the magnetically responsive superhydrophobic surfaces. The adhesion transition was attributed to the tunable mechanical properties of the MREMPs, which was easily controlled by an external m...
TL;DR: In this article, solvent-dependent emitting carbon dots (CDs) were synthesized by simple one-step hydrothermal treatment of o-phenylenediamine (oPD).
Abstract: In this study, solvent-dependent emitting carbon dots (CDs) were synthesized by simple one-step hydrothermal treatment of o-phenylenediamine (oPD). The as-prepared carbon dots (o-CDs) exhibited multi-color emission and strict excitation-independent luminescence characteristics in different solvents. Moreover, multi-color emissive o-CDs/polymer films were achieved through integrating the o-CDs with different polymer matrices. Interestingly, our experimental results demonstrated that distinctive o-CDs can also be used as fluorescent probes directly for visual and quantitative detection of water in different organic solvents. These investigations broaden the application of CDs and provide an easy method to quantitatively detect the presence of water in organic solvents.
TL;DR: In this paper, a rational strategy for scalable production of highly fluorescent CQDs in high yields (50-92%) based on controlled molecule fusion of activated polycyclic aromatic hydrocarbon in environmentally friendly polar solvents was reported.
TL;DR: The proposed TETA-DMCA solvent may be a suitable candidate for CO2 capture as it exhibited high cyclic capacity of CO2 absorption, favorable phase separation behavior, and low regeneration heat.
Abstract: The main issue related to the deployment of the amine-based absorption process for CO2 capture from flue gas is its intensive energy penalty. Therefore, this study screened a novel biphasic solvent, comprising a primary amine e.g., triethylenetetramine (TETA) and a tertiary amine e.g., N,N-dimethylcyclohexylamine (DMCA), to reduce the energy consumption. The TETA-DMCA blend exhibited high cyclic capacity of CO2 absorption, favorable phase separation behavior, and low regeneration heat. Kinetic analysis showed that the gas- and liquid-side mass transfer resistances were comparable in the lean solution of TETA-DMCA at 40 °C, whereas the liquid-side mass transfer resistance became dominant in the rich solution. The rate of CO2 absorption into TETA-DMCA (4 M, 1:3) solution was comparable to 5 M benchmark monoethanolamine (MEA) solution. Based on a preliminary estimation, the regeneration heat with TETA-DMCA could be reduced by approximately 40% compared with that of MEA. 13C NMR analysis revealed that the CO2...
TL;DR: Li et al. as mentioned in this paper exploited a thin-film rotating ring-disk electrode to show that soluble LiO2 is generated when oxidizing Li2O2 in high-donicity solvent but is absent in low-doniency glyme-based solvent.
TL;DR: In this paper, amorphous poly(lactic acid) (PLA) is successfully electrospun into micron-sized fibres with controlled surface and internal morphologies.
TL;DR: In this article, the authors reveal that DMF is actually a unique chemical since, as well as being an effective polar aprotic solvent, it can play three other important roles in organic chemistry.
Abstract: N,N-Dimethylformamide (DMF) is frequently used as an aprotic solvent in chemical transformations in laboratories of academia as well as in those of chemical industry. In the present review, we will reveal that DMF is actually something much more than a solvent. It is a unique chemical since, as well as being an effective polar aprotic solvent, it can play three other important roles in organic chemistry. It can be used as a reagent, a catalyst, and a stabilizer.
TL;DR: In this paper, a green, simple and scalable procedure was proposed to obtain phenolic resins which by pyrolysis at high temperature (>1000°C) result in eco-friendly hard carbons with low surface area, disordered structure and high carbon yield.
TL;DR: In this article, a homogenous and pinhole-free CsPbI 2Br films have been prepared with optimized solvent of DMF/DMSO mixture with the volume ratio of 3:2.
TL;DR: In this article, a simple solution-phase cross-linking process and electrospinning was proposed to overcome the instability of nanofibrous polyacrylonitrile (PAN) in industrially important polar solvents.
Abstract: Organic solvent nanofiltration (OSN) with thin film composite (TFC) membranes containing a thin selective layer on top of a porous substrate is key to lowering the energy costs of high-speed chemical separations Conventional TFC membranes were often built on phase inversion induced asymmetrical substrates with high tortuosity that impedes rapid solvent transport Nanofibers as ultrapermeable substrates have enhanced water transport in forward osmosis, nanofiltration and other aqueous separations However, problems of solvent stability under harsh operating conditions prevent their exploitation in non-aqueous molecular separations Here we show that by combining a simple solution-phase cross-linking process and electrospinning, the instability of nanofibrous polyacrylonitrile (PAN) in industrially important polar solvents can be overcome and harnessed to benefit the purification of polar solvents containing low molecular weight solutes The low tortuosity of electrospun PAN nanofibrous substrates is key to uniform cross-linking, and hence they are more stable and mechanically stronger than cross-linked PAN asymmetrical substrates fabricated by the traditional approach of phase inversion The low resistance offered by cross-linked nanofibrous substrates increased solvent permeation without sacrificing selectivity, for example, to 995% rejection of negatively charged Sudan 4 (MW: 380 Da) dye with a methanol permeance of 987 L m−2 h−1 bar−1 and water permeance of 2240 L m−2 h−1 bar−1 The enhanced stability of TFC membranes in polar aprotic solvents such as dimethylsulfoxide highlights their potential application for molecular separations in pharmaceutical and chemical industries
TL;DR: A comprehensive set of transferable parameters have been fine-tuned to accurately reproduce bulk-phase physical properties and local intermolecular interactions for 8 different choline chloride-based DESs and gave near quantitative agreement at multiple temperatures for experimental densities, viscosities, heat capacities, and surface tensions.
Abstract: Deep eutectic solvents (DES) are a class of solvents frequently composed of choline chloride and a neutral hydrogen bond donor (HBD) at ratios of 1:1, 1:2, or 1:3, respectively. As cost-effective and eco-friendly solvents, DESs have gained considerable popularity in multiple fields, including materials, separations, and nanotechnology. In the present work, a comprehensive set of transferable parameters have been fine-tuned to accurately reproduce bulk-phase physical properties and local intermolecular interactions for 8 different choline chloride-based DESs. This nonpolarizable force field, OPLS-DES, gave near quantitative agreement at multiple temperatures for experimental densities, viscosities, heat capacities, and surface tensions yielding overall mean absolute errors (MAEs) of ca. 1.1%, 1.6%, 5.5%, and 1.5%, respectively. Local interactions and solvent structuring between the ions and HBDs, including urea, glycerol, phenol, ethylene glycol, levulinic acid, oxalic acid, and malonic acid, were accurate...
TL;DR: In this article, the solvent-related effect on phase formation in CsBr-PbBr2 system through single crystal X-ray diffraction measurement is investigated thoroughly, and it is found that the prepared product is dominantly determined by the coordination number (CN) of Pb(II) and the ratio of precursors.
Abstract: All-inorganic cesium lead halide perovskite nanocrystals have emerged as attractive optoelectronic nanomaterials owing to their stabilities and highly efficient photoluminescence. However, the inorganic perovskites of CsPbBr3 synthesized by the solution method often suffer from byproducts such as Cs4PbBr6 and CsPb2Br5. Herein, we have investigated thoroughly the solvent-related effect on the phase formation in CsBr–PbBr2 system through single crystal X-ray diffraction measurement. It is found that the prepared product is dominantly determined by the coordination number (CN) of Pb(II) and the ratio of precursors. By use of dimethyl sulfoxide (DMSO) or dimethylformamide (DMF) as the solvent, Pb2+ is found to be surrounded by six-coordination sites, and the products can be tuned from CsPbBr3 to Cs4PbBr6 by increasing the precursor ratio of CsBr to PbBr2. On the contrary, in the solvent of water, only Pb2+ eight-coordinated crystal of CsPb2Br5 can be produced, regardless of the ratio of CsBr to PbBr2. More im...
Abstract: The rates of Bronsted-acid-catalyzed reactions of ethyl tert-butyl ether, tert-butanol, levoglucosan, 1,2-propanediol, fructose, cellobiose, and xylitol were measured in solvent mixtures of water with three polar aprotic cosolvents: γ-valerolactone; 1,4-dioxane; and tetrahydrofuran. As the water content of the solvent environment decreases, reactants with more hydroxyl groups have higher catalytic turnover rates for both hydrolysis and dehydration reactions. We present classical molecular dynamics simulations to explain these solvent effects in terms of three simulation-derived observables: (1) the extent of water enrichment in the local solvent domain of the reactant; (2) the average hydrogen bonding lifetime between water molecules and the reactant; and (3) the fraction of the reactant accessible surface area occupied by hydroxyl groups, all as a function of solvent composition. We develop a model, constituted by linear combinations of these three observables, that predicts experimentally determined rate constants as a function of solvent composition for the entire set of acid-catalyzed reactions.
TL;DR: In contrast to the common belief of humins consisting of polymers of large Mw, the authors postulate that they are spatially and chemically heterogeneous and consist of insoluble macromolecules and small soluble species that are weakly associated within the structure.
TL;DR: It is reported that FeII 4L4 cage 1 is able to extract an equimolar amount of ReO4 −, a high‐value anion and a nonradioactive surrogate of TcO 4 −, from water into nitromethane.
Abstract: Selective anion extraction is useful for the recovery and purification of valuable chemicals, and in the removal of pollutants from the environment. Here we report that FeII 4L4 cage 1 is able to extract an equimolar amount of ReO4 −, a high-value anion and a nonradioactive surrogate of TcO4 −, from water into nitromethane. Importantly, the extraction was efficiently performed even in the presence of 10 other common anions in water, highlighting the high selectivity of 1 for ReO4 −. The extracted guest could be released into water as the cage disassembled in ethyl acetate, and then 1 could be recycled by switching the solvent to acetonitrile. The versatile solubility of the cage also enabled complete extraction of ReO4 − (as the tetrabutylammonium salt) from an organic phase into water by using the sulfate salt of 1 as the extractant.
TL;DR: The OSFO process is a promising technology for solvent recovery as it possesses a reasonable solvent flux, low reverse solute flux and requires no external pressure, and may prove to be economically favorable.
Abstract: The organic solvent forward osmosis (OSFO) process can simultaneously concentrate the active pharmaceutical ingredients (APIs) and recover the organic solvents. Here we demonstrate and evaluate an OSFO process for solvent recovery. In this demonstration, OSFO was conducted in different solvents with different draw solutes. The OSFO process shows rejections >98% when recovering organic solvents from different feed solutions, even when the feed concentration is as high as 20 wt%. More importantly, all systems exhibit relatively low ratios of reverse solute flux to solvent flux, indicating that the adverse effects of using hazardous draw solutions could be minimized. Nevertheless, the use of non-hazardous draw solutes such as citric acid is highly recommended to remove any potential risk, and it has been demonstrated. Herein, the OSFO process is a promising technology for solvent recovery as it possesses a reasonable solvent flux, low reverse solute flux and requires no external pressure. Solvent recovery is an important process in the pharmaceutical industry, but organic solvent nanofiltration membranes operate under high pressures. Here the authors demonstrate organic solvent forward osmosis — an alternative process that does not require application of external pressure and may prove to be economically favorable.
TL;DR: The results of this study suggest that both the chemical structure of organic cations and alkaline media (fuels) applied affect the alkaline stability of AEMs.
Abstract: Alkaline alcohols (methanol, ethanol, propanol, and ethylene glycol) have been applied as fuels for alkaline anion exchange membrane fuel cells. However, the effects of alkaline media on the stability of anion exchange membranes (AEMs) are still elusive. Here, a series of organic cations including quaternary ammonium, imidazolium, benzimidazolium, pyridinium, phosphonium, pyrrolidinium cations, and their corresponding cationic polymers are synthesized and systematically investigated with respect to their chemical stability in various alkaline media (water, methanol, ethanol, and dimethyl sulfoxide) by quantitative 1H nuclear magnetic resonance spectroscopy and density functional theory calculations. In the case of protic solvents (water, methanol, and ethanol), the lower dielectric constant of the alkaline media, the lower is the lowest unoccupied molecular orbital (LUMO) energy of the organic cation, which leads to the lower alkaline stability of cations. However, the hydrogen bonds between the anions and protic solvents weaken the effects of low dielectric constant of the alkaline media. The aprotic solvent accelerated the SN2 degradation reaction of "naked" organic cations. The results of this study suggest that both the chemical structure of organic cations and alkaline media (fuels) applied affect the alkaline stability of AEMs.
TL;DR: In this article, 15 different types of amine and glycol-based deep eutectic solvents were synthesized and investigated for CO2 absorption, and the highest CO2 solubility was observed for the tetrabutyl ammonium bromide and methyldiethanol amine (TBAB/4MDEA).
Abstract: Anthropogenic CO2 emissions into the atmosphere are responsible for the global warming, therefore, it is essential to reduce these emissions at the source. Recently, deep eutectic solvents (DESs) have shown great potential to absorb the CO2. In the current study, 15 different types of amine- and glycol-based deep eutectic solvents were synthesized and investigated for CO2 absorption. In general, amine-based solvents have shown higher CO2 absorption as compared to glycol based solvents. In particular, the highest CO2 absorption was observed for the tetrabutyl ammonium bromide and methyldiethanol amine (TBAB/4MDEA) system having a CO2 solubility of 0.29 (mol CO2/mol solvent) at 1 MPa and 303.15 K. Thermophysical properties of all synthesized DESs were estimated using the modified Lydersen–Joback–Reid method and Lee–Kesler mixing rule. Experimental CO2 solubility data were well fitted using the nonrandom two liquid and the Peng–Robinson thermodynamic models. Apart, CO2 solubility data were correlated with He...