Low-toxicity Solvent Research Articles

Unexpectedly Superhigh Toxicity of Superbase-Derived Deep Eutectic Solvents albeit High Efficiency for CO2 Capture and Conversion

Superbase-derived deep eutectic solvents (DESs) are considered as biodegradable, low toxic, and sustainable solvents for efficient capture and conversion of carbon dioxide. However, do superbase-derived DESs have low toxicity just as reported? Herein, contradictory to the conventional thought, we find that the toxicity of superbase-derived DESs is super high. The toxicity of superbase-derived DESs in this work could be ca. 266 times that of DESs previously reported. Moreover, toxicity could be tuned by changing hydrogen bond donors, hydrogen bond acceptors, and mole ratios. The results indicate that the types of hydrogen bond donors had a paramount effect on the toxicity of DESs, and increasing the molar ratio of higher toxic components will also increase the toxicity of DESs. This work will provide possible ways to reduce the toxicity of DESs for achieving sustainable and green capture and conversion of carbon dioxide.

Optimisation of Low-Toxicity Solvent Employment for Total Lipid and Tocopherol Compound Extraction from Patagonian Squid By-Products.

The extraction of total lipids and tocopherol compounds from Patagonian squid (Doriteuthis gahi) by-products (viscera, heads, skin, etc.), resulting from squid mantel commercialisation, was studied. An optimisation simplex-lattice design by employing low-toxicity solvents (ethanol, acetone, and ethyl acetate) was carried out taking into account their relative concentrations. The variance analysis of data showed that the quadratic model was statistically significant (p < 0.05); empirical coded equations were obtained as a function of the low-toxicity solvent ratios. The optimised lipid extraction was obtained by employing the 0.642/0.318/0.040 (ethanol/acetone/ethyl acetate) solvent ratio, respectively, leading to an 84% recovery of the total lipids extracted by the traditional procedure. In all extracting systems tested, the presence of α-, γ-, and δ-tocopherol compounds was detected, α-tocopherol being the most abundant. For α-, γ-, and δ-tocopherol compounds, the optimisation process showed that acetone extraction led to the highest concentrations in the lipid extract obtained (2736.5, 36.8, and 2.8 mg·kg-1 lipids, respectively). Taking into account the recovery yield on a by-product basis, the values obtained for the three tocopherols were included in the 88.0-97.7%, 80.0-95.0%, and 25-75% ranges, respectively, when compared to the traditional extraction. This study provides a novel and valuable possibility for α-tocopherol extraction from marine by-products.

Solvent-free synthesis of photoluminescent carbon nanoparticles from lignin-derived monomers as feedstock

ABSTRACT Photoluminescent carbon nanoparticles (CNPs), such as carbon dots (CDs), have attracted much attention owing to a unique set of properties, like high and tunable fluorescence. In this way, the use of carbon-rich lignin has been demonstrated to be a sustainable approach to producing a broad range of photoluminescent CNPs. However, the valorization of this complex polyphenol is limited when it comes to green and efficient ways of conversion. In addition, the existing solvothermal approaches using lignin often result in CDs with low photoluminescence, while flammable and/or toxic solvents are employed. Here, we depolymerized technical lignins, i.e. kraft and soda, through electroreductive cleavage in two different sustainable media: deep eutectic solvent and levulinic acid. After depolymerization, lignin-derived monomers were generated, with a predominance of aryl ether and phenolic groups, which were further combined with 1,2-Phenylenediamine to produce N-doped CNPs in a solvent-free approach. Photoluminescent CNPs with varied sizes were generated (5–50 nm), which presented a wide photoluminescence emission, from blue to red, depending on solvent polarity. These results demonstrate a feasible and sustainable route for the solvent-free synthesis of photoluminescent CNPs using lignin-derived monomers as carbon source, which may find applications in a wide range of fields.

Microstructure and electrical properties of green electrospun PVDF-HFP nanofibers

Currently, with the recent increase of concern on the environmental hazards, toxicity, chemical and toxic waste, there has been growing interest in “green solvents” as alternative solvents instead of toxicity solvents. Most of the research reported on the preparation of Poly (vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) by using N, N- dimethylformamide (DMF) as a solvent which is considered a cancerogenic substance. Alternatively, dimethyl sulfoxide (DMSO) will be selectively decided as a low toxicity solvent and not hazardous. In this research, the mixture solvents of acetone/DMSO which was used as a co-solvent for the excellent fabricated PVDF-HFP nanofibers by using the electrospinning technique. The PVDF-HFP nanofiber membranes with various solvent ratios of 60:40, 70:30 and 80:20, denoted as A6D4, A7D3, and A8D2, respectively. All nanofiber films were investigated and characterized on the morphology, dielectric properties, and percentage of crystallinity. As a result, the dielectric constant of nanofiber membranes increased with the acetone contents. The maximum dielectric constant is devoted to A6D4 at 10 Hz. The copolymers structure with a different solvent ratio was modified β-phase which significantly affected the bandwidth dielectric properties. These fabricated PVDF-HFP nanofibers with the difference in the solution mixture can tune the electrical properties and phase orientation, and those fabricated nanofibers can be promoted in terms of energy storage, energy conversion, sensors, and electrocaloric application.

Novel extraction technologies and potential applications of egg yolk proteins.

The high nutritional value and diverse functional properties of egg yolk proteins have led to its widespread use in the fields of food, medicine, and cosmetics. Various extraction methods have been reported to obtain the proteins from egg yolk, however, their utilization is limited due to the relatively low extraction efficiency and/or toxic solvents involved. Several simpler and greener technologies, especially physical fields (ultrasound), have been successfully developed to improve the extraction efficiency. The egg yolk proteins may exert multiple biological activities, enabling them to be a promising tool in improve human health and wellbeing, such as anti-obesity, anti-atherosclerosis, anti-osteoporosis, diagnosis and therapy for SARS-CoV-2 infections. This article summarizes the novel extraction technologies and latest applications of the egg yolk proteins in the recent 5years, which should stimulate their utilization as health-promoting functional ingredients in foods and other commercial products.

Tailored Biocompatible Polyurethane-Poly(ethylene glycol) Hydrogels as a Versatile Nonfouling Biomaterial.

Polyurethane-based hydrogels are relatively inexpensive and mechanically robust biomaterials with ideal properties for various applications, including drug delivery, prosthetics, implant coatings, soft robotics, and tissue engineering. In this report, a simple method is presented for synthesizing and casting biocompatible polyurethane-poly(ethylene glycol) (PU-PEG) hydrogels with tunable mechanical properties, nonfouling characteristics, and sustained tolerability as an implantable material or coating. The hydrogels are synthesized via a simple one-pot method using commercially available precursors and low toxicity solvents and reagents, yielding a consistent and biocompatible gel platform primed for long-term biomaterial applications. The mechanical and physical properties of the gels are easily controlled by varying the curing concentration, producing networks with complex shear moduli of 0.82-190kPa, similar to a range of human soft tissues. When evaluated against a mechanically matched poly(dimethylsiloxane) (PDMS) formulation, the PU-PEG hydrogels demonstrated favorable nonfouling characteristics, including comparable adsorption of plasma proteins (albumin and fibrinogen) and significantly reduced cellular adhesion. Moreover, preliminary murine implant studies reveal a mild foreign body response after 41 days. Due to the tunable mechanical properties, excellent biocompatibility, and sustained in vivo tolerability of these hydrogels, it is proposed that this method offers a simplified platform for fabricating soft PU-based biomaterials for a variety of applications.

Photoinduced Iron-Catalyzed ATRP of Renewable Monomers in Low-Toxicity Solvents: A Greener Approach.

Producing polymers from renewable resources via more sustainable approaches has become increasingly important. Herein we present the polymerization of monomers obtained from biobased renewable resources, employing an environmentally friendly photoinduced iron-catalyzed atom transfer radical polymerization (ATRP) in low-toxicity solvents. We demonstrate that renewable monomers can be successfully polymerized into sustainable polymers with controlled molecular weights and narrow molar mass distributions (Đ as low as 1.17). This is in contrast to reversible addition–fragmentation chain-transfer (RAFT) polymerization, arguably the most commonly employed method to polymerize biobased monomers, which led to poorer molecular weight control and higher dispersities for these specific monomers (Đs ∼ 1.4). The versatility of our approach was further highlighted by the temporal control demonstrated through intermittent “on/off” cycles, controlled polymerizations of a variety of monomers and chain lengths, oxygen-tolerance, and high end-group fidelity exemplified by the synthesis of block copolymers. This work highlights photoinduced iron-catalyzed ATRP as a powerful tool for the synthesis of renewable polymers.

Influences of material and processing conditions on the depolymerization speed of anhydride-cured epoxy during the solvent-assisted recycling

Thermosetting polymers with permanent crosslinking networks have been intensively used in high-performance applications requiring thermal stability, chemical resistance, and structural integrity. However, they are extremely hard to be reprocessed and recycled using conventional techniques. The recently developed solvent-assisted recycling technique is shown to depolymerize and recycle thermoset wastes using low-toxic solvents and mild processing conditions. The macromolecular polymer chains can be cleaved at target covalent bonds on the chain backbone through bond exchange reactions with solvent molecules. In this study, the influences of various material and processing conditions on the network depolymerization speed are studied from both experimental and theoretical points of view. A diffusion-reaction chemomechanics modeling framework is defined to link the physical properties of organic solvent and microscale reaction kinetics to the overall depolymerization speed of thermosets at various material and processing parameters. The study reveals how the temperature, network crosslinking density, and physical properties of the solvent, in particular, the solvent diffusivity and solvent/polymer interactions would affect the depolymerization speed. It enhances our understanding of the underlying fundamentals of thermoset recycling using organic solvents, which provides valuable insights for industrials to optimize the recycling conditions and develop appropriate strategies for waste management. • Influencing mechanisms of various material and processing parameters are revealed. • A theory is defined to link solvent properties to the depolymerization speed. • There is an optical content of good solvent to maximize the depolymerization speed. • There are threshold values for solvent hydroxyl-hydrocarbon ratio and interaction parameters.

Ethanol-ammonium sulfate system based modified quick, easy, cheap, effective, rugged, and safe method for the determination of four neonicotinoid pesticide and metabolite residues in two canned fruits.

As the pesticide and its metabolite residues in processed fruits could become a significant route of human exposure. The work presented herein focuses on developing a feasible quick, easy, cheap, effective, rugged, and safe method with improved extraction and cleanup system for the determination of imidacloprid, acetamiprid, thiamethoxam, and clothianidin (a metabolite of thiamethoxam) in canned fruits. The low toxic solvent ethanol was used to extract the analytes, and ammonium sulfate was used to promote phase separation. Moreover, the carboxylated multi-walled carbon nanotube acted as the clean-up sorbent for the removal of high solubility impurities. The proposed method was validated with fortified real samples at different concentration levels (20-200 μg/kg). Recoveries obtained from three spiked levels (20, 50, and 200 μg/kg) ranged from 74.9 to 86.4% with relative standard deviations of the intra-day and inter-day in the range of 0.8-5.5 and 2.0-7.1%, respectively. The limits of detection ranged from 0.2 to 0.5 and 0.2 to 0.6 μg/kg for orange and peach, respectively. The results demonstrated that the proposed method could be considered appropriate, and comparatively lower toxic for the analysis of neonicotinoid pesticide residues in canned fruit.

Extraction of essential oils from tea tree (Melaleuca alternifolia) and lemon grass (Cymbopogon citratus) using betaine-based deep eutectic solvent (DES).

The essential oils of tea tree (Melaleuca alternifolia) leaves mainly contain eucalyptol, α-terpinene, -terpinene, and terpinen-4-ol and have anti-bacterial, anti-fungal, anti-infective, and anti-inflammatory actions. The essential oils of lemon grass (Cymbopogon citratus) leaves mainly contain neral, geranial, and geraniol and have anti-microbial and anti-fungal activities and hypocholesterolemic effect. The present study describes the use of low-toxicity solvents called betaine-based deep eutectic solvents (DESs) for efficient extraction of essential oils from tea tree and lemon grass. H2 O and EtOH were used for extraction as control methods. Quantitative analysis was performed using gas chromatography-mass spectrometry (GC-MS) in selected ion monitoring mode. Scanning electron micrography (SEM) and antioxidant assays for extracted samples were also conducted. The results indicated that extraction for tea tree using betaine/sucrose (molar ratio 2:1) improved the yields of terpinolene and eucalyptol 2.5- and 1.9-fold, respectively, compared with the control method. In lemon grass, extraction using betaine/sucrose (molar ratio 2:1) improved the yields of neral and geranial 1.9- and 1.7-fold, respectively, compared with the control method. These results demonstrated the effective extraction of essential oils from plant leaves under milder conditions than those needed for the conventional methods. The environmentally benign DESs for the extraction would be applicable to the food and cosmetic industries.

High efficiency preparation of standard grade γ‐tocopherol and its antioxidant activity

AbstractNatural standard grade γ‐tocopherol is of great interest due to its good antioxidant activity and special pharmacological functions. This study separated and purified γ‐tocopherol from mixed tocopherols using eco‐friendly and low toxicity solvents. γ‐Tocopherol (0.28 g) was obtained per performance with a purity of (98.89 ± 0.68)% and a recovery rate of (93.23 ± 0.89)%. The purification conditions were as follows: elution solvent n‐hexane/ethyl acetate 94.5:5.5 (v/v), sample load 0.5 g, a column height to diameter ratio of 16:1 (length and diameter, 60 × 3 cm) and an elution rate of 2 ml/min. The purity and structure of γ‐tocopherol was confirmed by high‐performance liquid chromatography, gas chromatography/mass spectrometry and nuclear magnetic resonance. The adsorption isotherm of γ‐tocopherol on silica gel (200–300 mesh) fitted the Langmuir isotherm model well. The antioxidant activity analysis showed that γ‐tocopherol had the strongest antioxidant activity followed by δ‐tocopherol and α‐tocopherol. This study provides an economically attractive solution for the production of natural standard grade γ‐tocopherol.

Investigation of the Morphological Structure of Needle-Free Electrospun Magnetic Nanofiber Mats

Electrospun magnetic nanofibers are promising for a variety of applications in biomedicine, energy storage, filtration or spintronics. The surface morphology of nanofiber mats plays an important role for defined application areas. In addition, the distribution of magnetic particles in nanofibers exerts an influence on the final properties of nanofiber mats. A simple method for the production of magnetic nanofiber mats by the addition of magnetic nanoparticles in an electrospinning polymer solution was used in this study. In this work, magnetic nanofibers (MNFs) were prepared by needle-free electrospinning technique from poly(acrylonitrile) (PAN) in the low-toxic solvent dimethy lsulfoxide (DMSO) and 20 wt% Fe3O4 at different parameter conditions such as PAN concentration, voltage and ultrasonic bath. The distribution of nanoparticles in the fiber matrix was investigated as well as the chemical and morphological properties of the resulting magnetic nanofibers. In addition, the surface morphology of magnetic nanofiber mats was studied by confocal laser scanning microscope (CLSM), scanning electron microscope (SEM), Fourier transform infrared microscope (FTIR) and ImageJ software, and distribution of Fe3O4 particles in the matrix was investigated by energy dispersive X-ray spectroscopy (EDX).

A highly efficient three-solvent methodology for separating colloidal nanoparticles.

This study has established a three-solvent methodology for separating nanomaterials, such as monometallic nanoparticles, miscible and immiscible nanoalloys. After systematically investigating the separation methods in two-solvent and three-solvent systems, a three-solvent theoretical model has been proposed to thoroughly reveal the centrifugation mechanism of colloidal particles. PVP plays an important role in the formation of emulsion droplets as the key factor for separation. Based on the three-solvent model, a novel solvent system has been discovered, with low-toxicity solvents and high separation efficiency. This study can open a new path for the separation of colloidal particles in both research and industrial fields and further promote the development of functional nanomaterials in greener pathways.

Radical selenation of C(sp3)-H bonds to asymmetric selenides and mechanistic study.

Selenides are important structural motifs with a broad range of biological activities and versatile transformational abilities. In this study, a novel and mild method was developed for the facile synthesis of asymmetric selenides under metal-free conditions. The key features of this reaction include good functional-group tolerance, the use of readily available reagents and cheap, low-toxicity solvent, and amenability to gram-scale synthesis. The results of preliminary radical-trapping experiments and a kinetic isotope effect study support a radical process.

KOH/thiourea aqueous solution: A potential solvent for studying the dissolution mechanism and chain conformation of corn starch

Non-derivatizing, high-efficiency and low-toxicity solvents are important for studying the dissolution behavior and potential applications of starch. In this study, we investigated the starch dissolution mechanism and molecular conformation in KOH/thiourea aqueous solutions and compared these with KOH/urea and KOH aqueous solutions. Solubility analysis revealed that the KOH/thiourea solution demonstrates a better ability to dissolve corn starch than KOH/urea and KOH solutions. Rheological behavior and dynamic and static light scattering indicated that starch is stable in KOH/thiourea solution and exists as a regular star structure. Fourier transform infrared spectroscopy, 13C NMR, and molecular dynamics simulations indicated that hydrated K+ and OH− destroy the strong starch hydrogen bond interactions; thiourea hydrate self-assembles into a shell surrounding the starch-KOH complex through interaction with KOH, whereas there is no direct strong interaction between urea and KOH. Therefore, adding thiourea to a KOH solution can promote dissolution and prevent self-aggregation of the starch chain.

On the Formation Mechanism of Nonsolvent-Induced Porous Polylactide Electrospun Fibers

Polylactide (PLA) fibers were electrospun from the solutions of PLA dissolved in the mixtures of its good and poor solvents, and the formation mechanism of the poor solvent-induced porous structure on the fibers was investigated. From a systematic study using the pairs of a variety of good/poor solvents for electrospinning, the conditions, specifically the solvent properties, for producing uniform fibers with controllable pores that appear not only on the surface but also throughout the fibers were proposed. The water miscibility of the good/poor solvents is crucial, which is because the ambient moisture that condenses during electrospinning plays an important role in the formation of the pores. Furthermore, the evaporation rate of the good/poor solvents is another key factor that affects the pore size and pore distribution on fibers because the solvent evaporation rate regulates the moisture condensation and the phase-separated scale that are closely related to fiber morphology. The principles generalized in this work can be applied to other low-polar polymers for controlling the porosity of fibers. In addition, this work demonstrates that the porous PLA fibers can be electrospun from low-toxic solvents and that with a large surface area and storage space provided by the pores, the PLA porous fibers are highly capable of adsorbing oils, with a capacity double that of the smooth counterpart.

Effective Extraction of Limonene and Hibaene from Hinoki (Chamaecyparis obtusa) Using Ionic Liquid and Deep Eutectic Solvent.

The essential oils of hinoki (Chamaecyparis obtusa) leaves have anti-bacterial, anti-fungal, and relaxation properties that are likely associated with the major components such as sabinene, α-terpinyl acetate, limonene, elemol, myrcene, and hibaene. The present study describes the use of a cellulose-dissolving ionic liquid (IL) [C2mim][(MeO)(H)PO2] and low-toxicity solvents called betaine-based deep eutectic solvents (DESs) for the efficient extraction of hinoki essential oils. As a control method, organic solvent extraction was performed using either hexane, ethyl acetate (EtOAc), or acetone at 30 °C for 1 h. Both the experimental and control methods were conducted under the same conditions, which relied on partial dissolution of the leaves using the IL and DESs before partitioning the hinoki oils into the organic solvent for analysis. Quantitative analysis was performed using gas chromatography–mass spectrometry (GC-MS) in selected ion monitoring (SIM) mode. The results indicated that extraction using the [C2mim][(MeO)(H)PO2]/acetone bilayer system improved the yields of limonene and hibaene, 1.5- and 1.9-fold, respectively, when compared with the control method. In addition, extraction using betaine/l-lactic acid (molar ratio 1:1) gave the greatest yields for both limonene and hibaene, 1.3-fold and 1.5-fold greater, respectively, than when using an organic solvent. These results demonstrate the effective extraction of essential oils from plant leaves under conditions milder than those needed for the conventional method. The less toxic and environmentally begin DESs for the extraction are also applicable to the food and cosmetic industries.

Characterization of poly(lactic-co-glycolic acid) nanofibers electrospun using a sustainable green chemistry with a low toxicity solvent system

There is a need to find alternative solvents for electrospinning that are less hazardous and more environmentally safe than the Class II solvents currently used. We characterized poly(lactic-co-glycolic acid) (PLGA) nanofibers (NFs) electrospun using a new, less toxic solvent system comprised the Class III solvents acetone:ethyl acetate (ACE:EtAc). Both solvent systems produced amorphous NFs. Fourier-transform infrared spectroscopy (FTIR) showed no change in PLGA composition after electrospinning. ACE:EtAc NFs showed a 53% burst release of paracetamol, followed by a gradual release not statistically different to release from DCM:DMF. ACE:EtAc can be used as a solvent to electrospin PLGA NFs however, with larger fiber diameter.

Современное состояние и технологические перспективы применения малотоксичных растворителей золота для переработки техногенного сырья

Современное состояние и технологические перспективы применения малотоксичных растворителей золота для переработки техногенного сырья

Optimizing Aerosol Jet Printing Process of Platinum Ink for High-Resolution Conductive Microstructures on Ceramic and Polymer Substrates.

Printing nano-ink with platinum nanoparticles to generate conductive microstructures for electronics on different types of substrates has gained increasing interest in recent years. To solve the problem of the low conductivity of platinum (Pt) nano-ink, we synthesized chemically pure Pt nanoparticles with sizes of 18.2 ± 9.0 nm by spark discharge method. A low toxic solvent, ethylene glycol with water, was used to ensure the aggregation stability of Pt nanoparticles. Polyvinylpyrrolidone was used as an adhesive additive and binder in the nano-ink. Narrow and conductive Pt lines were generated by aerosol jet printing technology. The resistivity of the Pt lines sintered at 750 °C on alumina substrate was found to exceed the bulk Pt by about 13%. Moreover, the Pt film fabricated on polymer substrates has demonstrated excellent mechanical flexibility in terms of twisting tests.