Low-toxicity Solvent Research Articles

3-Methylthiophene: A Sustainable Solvent for High-Performance Organic Solar Cells.

The use of harmful halogenated or aromatic solvents such as chloroform (CF), chlorobenzene (CB), and o-xylene (o-XY) is one of the greatest barriers to the industrial-scale manufacturing of high-performance organic solar cells (OSCs). Therefore, it is necessary to eliminate the effects of these solvents to ensure practical feasibility of OSCs. We found that the anthracene-terminated polymer donor and small-molecule acceptor BO-4Cl had good solubility in 3-methylthiophene (3-MeT). There were no toxicity labels in the SDS and exposure control limits for 3-MeT. An overall power conversion efficiency of 16.87% was achieved by using 3-MeT as the solvent for solar cell fabrication, which was higher than that of the cells made from CF (16.18%) and o-XY (15.69%). The best OSC based on PM6:D18:L8-BO and fabricated with 3-MeT exhibited a high PCE of 18.13%, which is one of the highest values for cells fabricated from halogen-free solvents. These results indicate that 3-MeT is an eco-friendly and low-toxicity solvent for the sustainable fabrication of the OSC active layer.

Fast, One‐Step In Situ Synthesis of a Hierarchical Sn4+‐Doped TiNb2O7 Nanosphere as a High‐Performance Anode Material

AbstractTitanium niobium oxide (TNO) exhibits great potential as a lithium‐ion battery anode due to its high capacity, minimal volume change during cycling, and safe good operation characteristic enabled from its voltage profile. However, its intrinsically low electronic and ionic conductivity hinders its potential for practical applications. This work proposes a facile coprecipitation method to address these limitations by incorporating a nano‐macro structure and in situ Sn ion doping into bulk TNO. This approach ensures homogeneous integration of TNO precursors and the Sn dopant at a molecular level within the co‐precipitation nanoparticles. Additionally, the use of low toxicity solvents facilitate scalability of the synthesis process. Excellent rate capability, high reversible capacities, and good capacity retention are achieved simultaneously due to synergistic effects of the bulk doping, which expands the crystal volume and enhances Li+ diffusion, combined with abundant surface area of the nano‐macro structures. The specific capacity of Sn‐doped TNO nanospheres remains at 180 mAh/g at a high current density of 40 C (1 C=400 mA g−1), which is nearly four times higher than that of undoped samples. Furthermore, the cyclic voltammetry analysis at various scanning rates reveals an increased Li+ diffusion rate in Sn doped titanium niobium dioxide.

On the Reversibility of Spray Adhesives in Paper Conservation

Abstract This research explores the practical advantages and potential applications of spray adhesives, focusing on testing their suitability for artwork mounting uses. Their solubility in common low-toxicity solvents (ethanol and acetone) was evaluated. Seven commercial spray adhesives from different commercial brands and compositions were applied on paper samples and subjected to different aging conditions. The samples were then immersed in the solvent, and the degree of adhesive removal was measured. One of the most relevant conclusions is that commercial neoprene-based spray adhesives become brittle and fragile in a few weeks, which makes them unsuitable for both long-term and temporary applications in the heritage field. On the other hand, the solubility was high or very high in some cases: up to 98 % of adhesive removal was achieved in acetone wash. These tests and the convenience, cost and availability of spray adhesives suggest that some of them may be safely used in some scenarios such as temporary mountings or transport.

Designing Low Toxic Deep Eutectic Solvents for the Green Recycle of Lithium-Ion Batteries Cathodes.

The Lithium-ion battery (LIB) is one of the main energy storage equipment. Its cathode material contains Li, Co, and other valuable metals. Therefore, recycling spent LIBs can reduce environmental pollution and resource waste, which is significant for sustainable development. However, traditional metallurgical methods are not environmentally friendly, with high cost and environmental toxicity. Recently, the concept of green chemistry gives rise to environmental and efficient recycling technology, which promotes the transition of recycling solvents from organic solvents to green solvents represented by deep eutectic solvents (DESs). DESs are considered as ideal alternative solvents in extraction processes, attracting great attention due to their low cost, low toxicity, good biodegradability, and high extraction capacity. It is very important to develop the DESs system for LIBs recycling for sustainable development of energy and green economic development of recycling technology. In this work, the applications and research progress of DESs in LIBs recovery are reviewed, and the physicochemical properties such as viscosity, toxicity and regulatory properties are summarized and discussed. In particular, the toxicity data of DESs are collected and analyzed. Finally, the guidance and prospects for future research are put forward, aiming to explore more suitable DESs for recycling valuable metals in batteries.

Photocatalytic α-aminoalkyl radical addition of amines mediated by benzophenone under visible light

The photocatalytic α-aminoalkyl radical addition of amines faciliated by benzophenone is disclosed. This is an example of a photocatalytic alkylation method that uses low-toxicity solvents and mild reaction conditions.

Biocompatible diimidazolium based ionic liquid systems for enhancing the solubility of paclitaxel

Diimidazolium ionic liquids, as low-toxicity solvents, are introduced into paclitaxel (PTX) dissolution systems for the first time, enhancing the dissolution of PTX in water and further promoting the design of biocompatible drug dissolution systems.

Obtaining nanocomposites based on recycled polystyrene from urban solid waste with carbon nanostructures: graphene oxide and multi-wall carbon nanotubes, modified with organic acids

The excessive use of polystyrene has caused great environmental problems at a global level, an alternative to reduce this problem is recycling, in order to obtain new products from waste, so the objective of this manuscript is to obtain nanocomposites (NCs) from recycled polystyrene with the integration of graphene oxide (OG) and multiple walled carbon nanotubes (NTCPM) previously modified with benzoic acid at concentrations of 0.33 and 5% respectively. Low toxicity solvent was used. The materials obtained were characterized by infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and light microscopy, finding by FTIR that the chemical structure of the polystyrene was not affected after the integration of the nanostructures and processing, which suggests that they are maintained the properties, regarding the optical micrographs, it can be observed that the NCs with the modified nanostructures presented a homogeneous dispersion, with respect to the thermogravimetric analysis, they increased 27 ° C in thermal stability.

Tandem Ring‐Opening/Double Ring‐Closing Synthesis of 1,2,4‐Triazolo[1,5‐a]pyridines from Chromone‐Containing Acrylonitriles

AbstractWe studied a reaction of chromone‐containing acrylonitriles and cyanoacrylates with acid hydrazides. This reaction turned out to be a method for the synthesis of salicyloyl‐substituted 1,2,4‐triazolo[1,5‐a]pyridines. The synthesis developed is a tandem ring‐opening/double ring‐closing process. This synthetic approach is characterized by low toxic solvents (ethanol, butanol) and mediator (Et3N), 37–84% yields, non‐chromatographic isolation of products, and substrate tolerance (59 examples).

Ionic liquid/covalent organic framework/silica composite material: Green synthesis and chromatographic evaluation

BackgroundDue to their large surface area and distinctive adsorption affinity, covalent organic frameworks (COFs) appear to be good candidates as liquid chromatographic separation materials with good application prospect. The development of COF materials in chromatographic science is currently in an exploratory stage. Especially, the practicability of COF@silica composite materials as liquid chromatographic stationary phases needs further exploration. Reasonably integrating a functional component such as ionic liquid (IL) into the COF@silica composite materials may provide customized functionality to achieve the purpose of synthesizing multi-functional COF based stationary phases. ResultsIn this study, an IL modified COF bonded silica composite material (IL-COF@SiO2) was successfully synthesized by using an environmentally friendly deep eutectic solvent as the reaction medium instead of the frequently-used organic solvent. The synthesized IL-COF@SiO2 composite material combines the excellent separation ability of COF and the excellent mass transfer function of spherical porous silica microsphere, and meanwhile, the introduction of IL endows COF@SiO2 with preferable separation performance. The slurry-packed IL-COF@SiO2 liquid chromatographic column could be applied to effectively separate hydrophobic and hydrophilic compounds with preferable separation selectivity and high column efficiency. By investigating the retention behavior and influencing factors, a mixed-mode retention mechanism was found. Multiple interaction forces endow the IL-COF@SiO2 with a hydrophilic-hydrophobic balance performance, demonstrating a good application prospect as a versatile liquid chromatographic separation material. SignificanceIn this study, a new strategy is proposed for greenly synthesizing a novel IL-COF@SiO2 composite material under mild conditions, which expands the potential application of COF materials in chromatographic science. One particular point to note is that the reaction medium in each step of the preparation process is low toxic and degradable deep eutectic solvent, which conforms to the concept of green chemistry.

Development and validation of an accurate, precise and safe method for the acceptance testing of recovered asphalt binder

With the ever-increasing use of recycled asphalt pavement (RAP) in road construction, extraction and recovery of binders from mixtures as placed becomes a critical aspect of quality assurance testing. However, current extraction and recovery methods are associated with shortcomings, as they are often time consuming, costly, inaccurate and involve toxic solvents. The objective of this study was to develop a practical and more environmentally friendly protocol for the accurate and precise acceptance testing of recovered binder. The process uses a low toxicity solvent for extraction, followed by simple filtration, evaporation and thin film oven aging. Residual solvent is removed from the binder during initial thin film oven aging and fines are found to have an insignificant effect on the rheological properties of importance. Results of this study provide guidance for further optimization of a simplified extraction, recovery, and aging protocol for the acceptance testing of asphalt binder and mixture.

Continuous catalytic esterification using a solid acid activated carbon monolith: Comparison of granular and monolith forms with a commercial catalyst

2-hydroxyisobutyric acid (2-HIBA) is a significant platform chemical for the synthesis of various products and has been produced fermentatively. Recently, the esters of 2-HIBA have gained interest for applications in fragrances and as low-toxic solvents. In this study, solid acid (sulfonated) wood-based activated carbon granular (sGAC) and monolith (sACM) catalysts were employed for the continuous esterification of 2-hydroxyisobuytric acid with ethanol. The effect of reaction conditions, including pressure and feed flow rate (Ql) on ester (ethyl 2-hydroxyisobutyrate) space–time yield (STY), ester yield, and selectivity, were determined. A higher STY of 96 g Lcat-1h−1 (341 g kg cat-1h−1) and selectivity of 76 % was achieved with the sACM compared to the sGAC (87 g Lcat-1h−1, 60 %) at 150 °C, 300 psig, and 3 mL min−1 (18.5–20 min contact time). At optimum pressure (300 psig) and temperature (150 °C for sGAC and sACM; maximum of 120 °C for Amberlyst), and in time-on-stream studies, 2-HIBA turnover frequency and ester selectivity were higher for sGAC and sACM over Amberlyst-15. The solid acid carbon monolith is a promising catalyst for the continuous catalytic upgrading of biobased organic acids.

Low-Toxicity Solvents for the Extraction of Valuable Lipid Compounds from Octopus (Octopus vulgaris) Waste.

This study focused on the recovery of valuable lipid compounds from octopus (Octopus vulgaris) by-products. Extraction conditions of total lipids (TLs), phospholipids (PLs), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) were optimized by employing a Simplex-Lattice design; for it, different relative concentrations of three low-toxicity solvents (ethanol, acetone, and ethyl acetate) were considered. The optimization process was also addressed in reference to fatty acid (FA) ratios (total polyunsaturated FAs/total saturated FAs and total ω3 FAs/total ω6 FAs). The variance analysis of multiple regression data demonstrated that the quadratic model was significant (p < 0.05) for TL, PL, and DHA values and the ω3/ω6 ratio. As a result, the following optimized values were obtained: 113.8 g·kg-1 dry by-products (TLs), 217.3 g·kg-1 lipids (PLs), 22.55 g·100 g-1 total FAs (DHA), and 3.70 (ω3/ω6 ratio). According to the model developed, optimized values were shown to correspond to the following relative solvent concentrations (ethanol/acetone/ethyl acetate): 0.46/0.00/0.54, 0.93/0.07/0.00, 0.83/0.17/0.00, and 0.64/0.00/0.36, respectively. Comparison to yields obtained by the conventional chloroform/methanol method was carried out. A novel strategy based on the employment of low-toxicity solvents is proposed for the extraction of valuable lipid constituents from octopus waste. A different solvent ratio would be necessary according to the lipid compound concerned.

A low-toxic, robust, and sensitive colorimetric sensor for the peroxide value of edible oils with CsPbBr3 NCs in ethyl acetate

Sensitively, accurately, and rapidly evaluating edible oils’ peroxide value (PV) is significant for safeguarding food quality and safety. However, the conventional detection methods are challenging to meet the above demands due to their complex operation, poor reproducibility, and professional personnel. The colorimetric method is an emerging technique to rapidly and on-site determine the PV of edible oils. CsPbBr3 NCs, as a novel fluorescent-sensing material, have been applied in the chemical colorimetric analysis. However, the heavy use of high-toxic solvents (toluene, chloroform) in the CsPbBr3 NCs colorimetric system significant-negatively influences the environment. This study evaluated the performances of CsPbBr3 NCs in nine low-toxic solvents and investigated the potential response mechanism to PV. The results presented that CsPbBr3 NCs in ethyl acetate displayed the highest photoluminescent intensity and the most uniform distribution. The results performed that the micro-morphology and crystal structure of CsPbBr3 NCs in ethyl acetate were similar to that in toluene, demonstrating the potential excellent performance. Under optimum conditions, three methods, including photoluminescence (PL)-decreased, wavelength-shifted, and phone-based colorimetric methods, were established to evaluate PV with the LOD of 0.0034 g/100 g. The PV recovery rates in Soybean oil, Camellia oil, Linseed oil, and Olive oil were from 75.0% to 100.0%, with a relative error below 25%. Furthermore, it was believed that the decreased PL and shifted wavelength originated from the halogen substitution with the crystal-structure destructions and the surface-defect formations. Thus, developing the low-toxic colorimetric CsPbBr3 NCs system with ethyl acetate could reduce the environmental influence and even enlighten the rise of other green detection methods for PV in edible oils.

A Formulation for a New Environmentally Friendly Varnish for Paintings

Laropal® A81 is a urea-aldehyde resin used as a varnish for paintings requiring 30%–40% of aromatic solvents to be dissolved. Considering the dangers of aromatic solvents for the environment and health, an attempt was made to replace them with less impactful and low-toxic solvents. The present research investigates a new formulation with aliphatic hydrocarbons and esters (isobutyl isobutyrate, IBIB) as an alternative to traditional aromatics mixture. Traditional and alternative varnish formulations of Laropal® A81 were studied on an inert support and paint samples to test the resin by itself and in interaction with paint film, respectively. This study aims to compare the two different formulations of Laropal® A81 by evaluating their optical, colorimetric, and stability proprieties before and after natural and accelerated ageing. Colorimetry and spectroscopic techniques (transmittance and reflectance UV-VIS-NIR, FORS, transmittance and total reflectance FT-IR, and 1H-NMR) were used for the assessment. Very promising results have been obtained with the application of the alternative formulation, with data comparable to those of the traditional formulation, paving the way for the replacement of the aromatic-based solvents traditionally used with IBIB. This allows a safer and more sustainable conservation practice with considerable benefits for the health of the operators and the environment.

Environmentally Friendlier Printable Conductive and Piezoresistive Sensing Materials Compatible with Conformable Electronics.

Flexible and conformable conductive composites have been developed using different polymers, including water-based polyvinylpyrrolidone (PVP), chemical-resistant polyvinylidene fluoride (PVDF), and elastomeric styrene-ethylene-butylene-styrene (SEBS) reinforced with nitrogen-doped reduced graphene oxide with suitable viscosity in composites for printable solutions with functional properties. Manufactured by screen-printing using low-toxicity solvents, leading to more environmentally friendly conductive materials, the materials present an enormous step toward functional devices. The materials were enhanced in terms of filler/binder ratio, achieving screen-printed films with a sheet resistance lower than Rsq < 100 Ω/sq. The materials are biocompatible and support bending deformations up to 10 mm with piezoresistive performance for the different polymers up to 100 bending cycles. The piezoresistive performance of the SEBS binder is greater than double that the other composites, with a gauge factor near 4. Thermoforming was applied to all materials, with the PVP-based ones showing the lowest electrical resistance after the bending process. These conductive materials open a path for developing sustainable and functional devices for printable and conformable electronics.

Air-Knife-Assisted Spray Coating of Organic Solar Cells.

The power conversion efficiencies (PCEs) of organic solar cells (OSCs) have risen dramatically since the introduction of the "Y-series" of non-fullerene acceptors. However, the demonstration of rapid scalable deposition techniques to deposit such systems is rare. Here, for the first time, we demonstrate the deposition of a Y-series-based system using ultrasonic spray coating─a technique with the potential for significantly faster deposition speeds than most traditional meniscus-based methods. Through the use of an air-knife to rapidly remove the casting solvent, we can overcome film reticulation, allowing the drying dynamics to be controlled without the use of solvent additives, heating the substrate, or heating the casting solution. The air-knife also facilitates the use of a non-halogenated, low-toxicity solvent, resulting in industrially relevant, spray-coated PM6:DTY6 devices with PCEs of up to 14.1%. We also highlight the obstacles for scalable coating of Y-series-based solar cells, in particular the influence of slower drying times on blend morphology and crystallinity. This work demonstrates the compatibility of ultrasonic spray coating, and use of an air-knife, with high-speed, roll-to-roll OSC manufacturing techniques.

Yield Enhancement of Valuable Lipid Compounds from Squid (Doryteuthis gahi) Waste by Ethanol/Acetone Extraction.

The study focused on the extraction of valuable lipid compounds from squid (Doryteuthis gahi) waste by a low-toxicity solvent mixture (ethanol/acetone, 50:50, v/v). The effect of the waste weight/solvent volume (WW/SV, g·mL-1) ratio and the number of extractions (NoE) on the total lipid (TL), phospholipid (PL), and tocopherol yields and on the fatty acid (FA) profile (eicosapentaenoic and docosahexaenoic acid contents; polyunsaturated FAs/saturated FAs and ω3/ω6 ratios) was investigated. As a result, an increased NoE led to an increased (p < 0.05) TL yield but a decreased (p < 0.05) proportion of PLs in the lipid extract. Additionally, a lower (p < 0.05) polyunsaturated FA/saturated FA ratio was detected by increasing the NoE. Some differences (p < 0.05) could be outlined as a result of increasing the WW/SV ratio; however, a definite trend for this extraction condition could not be concluded for any of the lipid parameters measured. Yield results were compared to those obtained by the conventional chloroform/methanol procedure. In order to attain an increased yield, the NoE required would depend on the polarity degree of the lipid molecule concerned. All ethanol/acetone extracting conditions tested led to remarkable yields for lipid compounds (PLs, α-tocopherol, ω3 FAs) and FA ratios with healthy, nutritional, and preserving properties.

Advanced methodologies for the cleaning of works of art

AbstractCultural heritage assets constitute a fundamental socioeconomic resource, but the actual works of art need to be maintained, counteracting degradation processes, to transfer these benefits to future generations. In particular, the removal of soil, aged coatings, and vandalism/overpaints is one of the most needed interventions in art restoration. Traditional cleaning methodologies, based on classical solution and polymer chemistry, only grant limited control of the cleaning interventions, with the risk of affecting the original components of the artifacts, and often involving the use of toxic or non-environmentally friendly compounds. Alternatively, materials science, colloids, and soft matter have provided valuable and safe solutions in the last decades. This review provides a selection of the most recent and advanced methodologies for the wet cleaning of works of art, spanning from nanostructured cleaning fluids (microemulsions, surfactants swollen micelles) to physical and chemical gels. The new methodologies work on different physico-chemical mechanisms, such as processes for detaching/dewetting, to selectively remove the unwanted layers in sustainable and cost-effective interventions. The best performing systems, like microemulsions confined in “twin-chain” polyvinyl alcohol gels, have been assessed in the cleaning of masterpieces such as works by Pablo Picasso, Jackson Pollock and Roy Lichtenstein. Particular attention is dedicated to “green” chemistry systems, using low-toxicity solvents or bio-based/waste materials to build gel networks. Finally, current trends and future perspectives are given, showing that advanced systems for art cleaning link with transversal fields of crucial importance even beyond Cultural heritage conservation, e.g., detergency, tissue engineering, drug-delivery, food industry and cosmetics.

Identification of an unusual pale green material on the surface of an ancient Chinese bronze vessel and application of laser cleaning to its removal

An ancient Chinese bronze vessel represented a typical difficult situation for conservation: a large quantity of an unwanted pale green material of unknown nature adhered to a surface fully decorated with delicate relief. The diagnostic itinerary, beginning with in-situ Raman spectroscopy analysis and followed by scanning electron microscopy-energy dispersive spectroscopy and X-ray diffraction, was found to be advantageous in revealing the presence of both inorganic and organic compounds in the pale green material. Irradiation with pulsed Nd:YAG 1064 nm laser in LQS regime (100 ns) followed by chemical cleaning using a low-toxicity solvent mixture proved to be respectful towards the original patina of the bronze as well as of high efficiency. Tentative analyses with the Raman spectroscopy and hyperspectral imaging were conducted to provide further indications on quality and visual effect during the cleaning result assessment. In parallel with the analyses and interventions on the bronze vessel, experiments were also carried out on mock-up samples in order to further explore the Raman scatter property and reactivity with laser ablation of mixed materials. The study provided reference for the optimization of diagnostic and conservation for the bronze artwork with similar situation.

Direct Determination of 2-Acetyl-1-Pyrroline in Rice by Ultrasound-Assisted Solvent Extraction Coupled with Ultra-performance Liquid Chromatography-Tandem Mass Spectrometry

In this paper, we present a novel direct detection method for the characteristic fragrant component 2-acetyl-1-pyrroline (2-AP) in rice by using ultrasound-assisted solvent extraction (UASE) coupled with ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). No tedious derivatization procedures and toxic solvents were involved in the sample preparation process. 2-AP was extracted with ethanol by UASE from rice samples, and remained good stability within 27 h. By direct injection to UPLC-MS/MS, accurate results were obtained through matrix-matched internal standard calibration. Under optimized conditions, good repeatability (2.8%), reproducibility (7.6%), and recoveries (83.9–108%) were achieved with the limit of detection down to 0.3 μg/kg. The results of 2-AP in 13 rice samples determined by the present method were in the range of 19.4–124.0 μg/kg. The sensitivity and reliability of the developed UASE UPLC-MS/MS method are comparable with previously published SPME GC–MS/MS methods or derivatization-based HPLC–MS/MS method. High analysis throughput, low laboriousness, excellent accuracies, and low toxic solvent consumption are the main characteristics of the newly presented method.