Non-toxic Solvent Research Articles

Pressurized Natural Deep Eutectic Solvent Extraction of Galanthamine and Related Alkaloids from Narcissus pseudonarcissus.

The isolation of a compound from a natural source involves many organic and mostly toxic solvents for extraction and purification. Natural deep eutectic solvents have been shown to be efficient options for the extraction of natural products. They have the advantage of being composed of abundantly available common primary metabolites, being nontoxic and environmentally safe solvents. The aim of this study was to develop a natural deep eutectic solvent-based extraction method for galanthamine, an important therapeutic agent for the treatment of Alzheimer's disease. This alkaloid can be produced by synthesis or by extraction from Narcissus bulbs. To develop an efficient extraction method, a number of different natural deep eutectic solvents was first tested for their solubilization capacity of galanthamine bromide salt. Promising results were obtained for ionic liquids, as well as some amphoteric and acidic natural deep eutectic solvents. In a two-cycle extraction process, the best solvents were tested for the extraction of galanthamine from bulbs. The ionic liquids produced poor yields, and the best results were obtained with some acid and sugar mixtures, among which malic acid-sucrose-water (1 : 1 : 5) proved to be the best, showing similar yields to that of the exhaustive Soxhlet extraction with methanol. Furthermore, the natural deep eutectic solvent was more selective for galanthamine.

A green microfluidic method based liquid phase microextraction for the determination of parabens in human urine samples

Development of green approaches have emerged as a challenge that highlight the pressing need for nontoxic solvents, miniaturized method and bio-degradable materials. In this regard, an environmentally-friendly microfluidic system based on natural deep eutectic solvents (DESs) immobilized in agarose membranes was developed to extract parabens from urine samples for the first time. A comprehensive study of the support liquid membrane showed that only 3 µL of camphor and thymol (2:1 molar ratio) was an interesting option as a substitute for conventional (toxic) solvents used to date. Other experimental conditions were optimized and pH 4 (HCl) and 12 (NaOH) were selected as sample and acceptor solution, respectively. Both solutions (sample and acceptor) were fixed at 1 µL min−1 as flow rate. The proposed green microfluidic device was successfully applied for the determination of parabens in urine samples with relative recoveries between 86 and 100% for all analytes. Detection limits and quantitation limits were between 0.011–0.093 and 0.31–0.38 µg mL−1, respectively. Relative standard deviation was below 7% for all analytes. Furthermore, the environmentally-friendly solvent (Ca:Ty 2:1) used as SLM offered the same advantages in terms of membrane stability allowing consecutive extractions. Results were compared with experiments previously conducted using conventional (polypropylene) membranes, observing that highly green microextraction systems based on natural and biodegradable materials have proven to be an attractive alternative in microfluidic systems.

Extraction of chlorogenic acids from hibiscus (Hibiscus syriacus L.) by subcritical-water

Chlorogenic acids are formed from hibiscus (Hibiscus syriacus L.) by ester bonding of caffeic acid and quinic acid, and they have isomers named neochlorogenic acid (NCGA) and cryptochlorogenic acid (CrCGA) that are esterified on different sites of caffeic acid. Subcritical-water extraction (SWE) is an ecofriendly and highly efficient technique because it utilizes a nontoxic solvent and has a very short extraction time. Twenty different SWE conditions were applied to hibiscus, with extraction times of 10–40 min, and extraction temperatures of 110–190 °C. The concentrations of chlorogenic acid, NCGA, and CrCGA were maximal for extraction conditions of 190 °C/10 min, 110 °C/10 min, and 130 °C/40 min, respectively. The extraction efficiency varied with the extraction conditions among the three isomers due to the hydrophilicity of the hydroxyl residue depending on the steric structure, the stability of the steric structure varying with the position of the acyl group, and the isomerization caused by the reversible movement of the acyl group.

ITO‐Free Indoor OPV Modules from Nonhalogenated Solvents

The growing market of the internet‐of‐things (IoT) accelerates the development of indoor organic photovoltaics. Very high performances up to 29% are already achieved under illumination with white light‐emitting diodes with intensities in the range of 500–1000 lux. However, topics relevant for mass production such as large area coating, use of nontoxic solvents, and inexpensive electrodes are hardly addressed thus far. Herein this work, an indium‐tin‐oxide‐free device stack is presented, which shows very good performance with many novel absorber materials under both full sun light as well as indoor illumination. Furthermore, lab‐scale cells are upscaled to small modules that can power typical IoT devices. This includes the transition from spin coating to slot‐die coating as well as the use of green solvents. Further, as the parallel resistance (RP) is crucial for the performance under low illumination intensities, a detailed analysis is carried out and it is found that a one‐diode model with the RP being determined from the dark current–voltage characteristics reproduces the behavior quite accurately. Efficiencies of 19.3% on cell level and above 17% on an 8.1 cm2 module with eight interconnected cells are achieved under 500 lux cold white light‐emitting diode illumination.

Liquid-liquid extraction of lactic acid using non-toxic solvents

Lactic acid is a carboxylic acid that is important due to its applications in various industries like pharmaceutical, cosmetics, chemicals, and food industries. It can be used for the production of ethanol, acrylic polymers, and propylene glycol. However, lactic acid extraction from downstream is a major challenge, hence an attempt was made to recover the acid by liquid-liquid extraction from the aqueous stream. In this paper, the extraction of lactic acid from the water stream was done using rice bran, sesame, and mustard oil. The experimental data were defined in different parameters viz. distribution coefficient (K D ) and extraction efficiency (η) at 298.15 1 K. The distribution coefficient and extraction efficiency were found as follows: Sesame oil (0.28, 22.37%) > Rice Bran oil (0.19, 16.66%) > Mustard oil (0.13, 12.16%).

Turning mannitol-rich agricultural waste to poly(3-hydroxybutyrate) with Cobetia amphilecti fermentation and recovery with methyl levulinate as a green solvent

The present study explored the use of mannitol and mannitol-rich agro-industrial wastes as substrates for PHB production by Cobetia amphilecti isolated from the green Ulva sp. seaweed. Cultivation of C. amphilecti on mannitol, celery, and olive leaves (OLs) waste led to 4.20, 6.00, and 5.16 g L−1 of cell dry mass (CDM), 76.3, 25.5, and 12.0% of PHB content in CDM and 3.2, 1.53, and 0.62 g L−1 of PHB concentration, respectively; which suggested that they can be exploited as carbon substrates for the production of PHB. Extraction of PHB from C. amphilecti cultures by solubilization in the green solvent methyl levulinate (ML) (2% w/w, 140 °C, 1 h) indicated that the recovery yield and purity of PHB are above 97 and 90% w/w, respectively. The use of ML could be an attractive method for the recovery of PHB when safe and non-toxic solvents are required.

Obtaining EPA-rich polar lipids from microalga Nannochloropsis sp. by silica-gel chromatography using non-toxic solvents

Current research indicates that n-3 polyunsaturated fatty acids (PUFAs) bind to polar lipids (phospholipids and glycolipids) seem to exert a greater bioavailability compared to their neutral forms. The aim of this work was to obtain eicosapentaenoic acid (EPA) rich polar lipids from the saponifiable lipids (SLs) extracted from the microalga Nannochloropsis sp. (33.4 ± 0.1% of EPA; 60 ± 0.6% polar lipids) by fractionation using silica-gel columns and importantly, non-polar and polar (ethanol) non-toxic solvents. Nowadays, few studies have been conducted towards the extraction and purification of polar lipids. Firstly, the solvent type for obtaining the neutral saponifiable lipid (NSL) fraction (ethyl acetate, EA, butyl acetate, BA) and the SL/silica-gel, SL/BA, and SL/ethanol ratios were optimized in a small silica-gel cartridge (0.69 g silica gel). The optimized conditions were an SL/silica-gel ratio of 22.6 mg/g, an SL/BA ratio of 1.56 mg/mL and an SL/ethanol ratio of 0.312 mg/mL. Next, the fractionation scale was increased to a column containing 10 g of silica-gel. At this scale, a BA SL fraction was obtained with 96.2 ± 0.5% of NSLs, and an ethanol SL fraction containing 97.7 ± 0.3% of polar lipids and 44.9 ± 0.2% of EPA. In the ethanol fraction, 86.6 ± 0.2% of the polar lipids and 71.5 ± 0.4% of the EPA from the SL microalgal extract were recovered. Consequently, EPA-rich polar lipids were obtained at high yields and purities, which could be used as a source of n-3 PUFAs with greater bioavailability than those based on neutral lipids.

Study on the Alternative Solvent of Methylbenzene in the Total Acid Number Titration of Current Jet Fuels.

Evaluation of the acidic characteristics of a jet fuel, especially for the total acid number (TAN), is of great significance to ensure flight safety. Methylbenzene is commonly used as the titration solvent; however, it is poisonous and harmful to the environment. It is highly desirable to develop an alternative solvent for methylbenzene to extract the acidic compounds from the jet fuel during the determination of the TAN. Here, we develop a desirable alternative solvent of a mixed ethanol–water solution with the volume ratio of ethanol to water of 99:1, which exhibits a value of TAN similar to that of the solvent of methylbenzene in potentiometric titration and acid–base titration methods. The TAN value derived from the different titration solvents was in the order of 2.96 μg KOH g–1 (Vcyclohexane/Visopropanol/Vwater = 100:99:1) > 2.68 μg KOH g–1 (Vmethylbenzene/Visopropanol/Vwater = 100:99:1) ≈ 2.6 μg KOH g–1 (Vabsolute ethanol/Vwater = 99:1) > 2.34 μg KOH g–1 (Visopropanol/Vwater = 99:1). The current report presents a nontoxic and eco-friendly alternative solvent for methylbenzene, which may open up an avenue for evaluating the TAN of jet fuels.

Extraction of Bioactive Compounds from Ulva lactuca

Macroalgae Ulva lactuca, has been employed as a natural source for the production of extracts with potent bioactivity. The biochemical characterization showed that the macroalgae biomass contains a remarkable amount of the polysaccharide Ulvan (49.9 wt%) which is a valuable chemical compound well known for its benefits in human health. Four nontoxic solvents, water, ethyl acetate, ethanol, and an ethanol/water mixture (70:30 v/v) were examined for their recovery efficiency of total carotenoid and phenolic contents. Experimental results showed that the aqueous mixture of ethanol was the most efficient solvent in the recovery of bioactive compounds with extraction yield of 10–15% dw. The effect of extraction parameters, namely time, temperature, and the ratio of biomass to solvent, on the carotenoid and phenolic compounds’ content, antioxidant activity, and extraction yield, was investigated, using the ethanol/water mixture as a solvent. The extract obtained under 60 °C, 3 h of extraction time and 1:10 biomass to solvent mass ratio showed the highest antioxidant activity. This extract maintained its antioxidant capacity almost stable for five days of storage under cool and dark conditions. Finally, specific phenolic and carotenoid compounds in the U. lactuca extracts were identified using the High-Performance Liquid Chromatography (HPLC) technique.

Supercritical CO2 Plant Extracts Show Antifungal Activities against Crop-Borne Fungi.

Fungal infections of cultivated food crops result in extensive losses of crops at the global level, while resistance to antifungal agents continues to grow. Supercritical fluid extraction using CO2 (SFE-CO2) has gained attention as an environmentally well-accepted extraction method, as CO2 is a non-toxic, inert and available solvent, and the extracts obtained are, chemically, of greater or different complexities compared to those of conventional extracts. The SFE-CO2 extracts of Achillea millefolium, Calendula officinalis, Chamomilla recutita, Helichrysum arenarium, Humulus lupulus, Taraxacum officinale, Juniperus communis, Hypericum perforatum, Nepeta cataria, Crataegus sp. and Sambucus nigra were studied in terms of their compositions and antifungal activities against the wheat- and buckwheat-borne fungi Alternaria alternata, Epicoccum nigrum, Botrytis cinerea, Fusarium oxysporum and Fusarium poae. The C. recutita and H. arenarium extracts were the most efficacious, and these inhibited the growth of most of the fungi by 80% to 100%. Among the fungal species, B. cinerea was the most susceptible to the treatments with the SFE-CO2 extracts, while Fusarium spp. were the least. This study shows that some of these SFE-CO2 extracts have promising potential for use as antifungal agents for selected crop-borne fungi.

Parameter screening, optimization and artificial neural network modeling of cadmium extraction from aqueous solution using green emulsion liquid membrane

This research was aimed to investigate the extraction of cadmium using waste cooking oil (WCO) based emulsion liquid membrane. The green emulsion liquid membrane (GELM) phase consists of waste cooking oil, a non-toxic solvent as diluent, Span 80 as surfactant, D2EHPA (Bis (2-ethylhexyl) phosphoric acid) as carrier, and hydrochloric acid solution as stripping phase. The influence of the operating parameters namely surfactant concentration (1–5v/v%), carrier concentration (2–6v/v%), agitation speed (200–600 rpm), agitation time (10–15​ min), pH of the feed solution (4–6), treat ratio (1:10–1:15), internal stripping agent (HCl) concentration (0.5–1.5 N), initial cadmium ion concentration (100–500 mg/L) and phase ratio (1:1–1:3) were studied to identify the key variables to be screened using Placket Burman design based on ‘P’ value. The significant variables were then optimized using Box–Behnken design. The stripping efficiency of cadmium was verified by varying the HCl concentration. The recycling and reuse of membrane phase was studied for 8 cycles. The mechanism of cadmium extraction by GELM was investigated. The feed forward neural network (FFNN) model having input layer composed of 5 neurons and output layer with 1 (cadmium extraction) neuron was employed to model the extraction data.

Long-term stable perovskite solar cells prepared by doctor blade coating technology using bilayer structure and non-toxic solvent

The doctor blade coating technology for the perovskite solar cells (PSCs) is studied. The bilayer and triple-layer structures based on CsFAPb(IBr)3 and MAPbI3 layers were designed and fabricated by the doctor blade coating. The conventional highly toxic dimethylformamide (DMF) used in the precursors are replaced by the mixtures of gamma-butyrolactone (GBL) and dimethyl sulfoxide (DMSO). Single cation and mixed-cation perovskite layer with different stacks are also compared. It is found that the as-prepared single cation perovskite (MAPbI3) PSCs have better photovoltaic performance but worse lifetime than those of the mixed-cation perovskite (CsFAPb(IBr)3) PSCs. Additionally, the bi-layer structure PSC has a brighter and smoother surface, higher quantum efficiency, and higher crystallinity. Those factors concerning the MAPbI3/CsFAPb(IBr)3(upper/lower) solar cell to have superior properties and better lifetime under the elevated temperature and humidity than that of the CsFAPb(IBr)3/MAPbI3(upper/lower) solar cell. Moreover, when the MAPbI3 is used as the capping layer of the CsFAPb(IBr)3/MAPbI3 bilayer PCS, its photovoltaic performance is better. Secondary ion mass spectroscopy indicates that MAPbI3 capping layer has better ability to dissolve the bottom layers than that of CsFAPb(IBr)3 due to the reduction of inter-diffusion of molecules and smooth surface during lifetime test. Finally, the MAPbI3/CsFAPb(IBr)3 bilayer device shows the best initial power conversion efficiency (PCE), Voc, and Jsc of 15.4%, 1.01 V, and 20.7 mA/cm2 respectively. The encapsulated PSC keeps 92% of original PCE under ambient environment at room temperature and relative humidity of 40% after 1000 h.

A General Method for the Synthesis of 11H-Indeno[1,2-B]Quinoxalin- 11-Ones and 6H-Indeno[1,2-B]Pyrido[3,2-E]Pyrazin-6-One Derivatives Using Mandelic Acid as an Efficient Organo-catalyst at Room Temperature

Aims: Synthesis of 11H-indeno[1,2-b]quinoxalin-11-ones as well as 6H-indeno[1,2-b]pyrido[3,2-e]pyrazin-6-one derivatives under greener conditions. Background: Quinoxaline and related skeletons are very common in naturally occurring bioactive compounds. Objective: Design a facile, green and organo-catalyzed method for the synthesis of 11H-indeno[1,2-b]quinoxalin-11-ones as well as 6H-indeno[1,2-b]pyrido[3,2-e]pyrazin-6-one derivatives. Methods: Both the scaffolds were synthesized via the condensation of ninhydrin and o-phenylenediamines or pyridine-2,3-diamines respectively by using a catalytic amount of mandelic acid as an efficient, commercially available, low cost, organo-catalyst in aqueous ethanol at room temperature. Results: Mild reaction conditions, use of metal-free organocatalyst, non-toxic solvent, ambient temperature, and no column chromatographic separation are some of the notable advantages of our developed protocol. Conclusion: In conclusion, we have developed a simple, mild, facile and efficient method for the synthesis of structurally diverse 11H-indeno[1,2-b]quinoxalin-11-one derivatives via the condensation reactions of ninhydrin and various substituted benzene-1,2-diamines using a catalytic amount of mandelic acid as a commercially available metal-free organo-catalyst in aqueous ethanol at room temperature. Under the same optimized reaction conditions, synthesis of 6H-indeno[1,2-b]pyrido[3,2-e]pyrazin-6-one derivatives was also accomplished with excellent yields by using pyridine-2,3-diamines instead of o-phenylenediamine.

Usefulness of a tissue optical clearing technique for forensic autopsy.

Forensic pathologists are required to investigate lethal trauma or disease at autopsy. In addition to massive contusions of various organs, a number of small features with potentially fatal implications also need to be sought. Since such lesions may need microscopic examinations for detailed evaluation, it is important to select suitable anatomic locations for tissue sampling. For practical screening of small lesions, we have developed a tissue optical clearing (TOC) technique for forensic autopsy. The technique involves clearing with a non-toxic organic solvent, ethyl cinnamate, which renders excised organs transparent, while hemorrhages or blood-containing vessels remain opaque. Using this technique, tiny hemorrhages in the spinal cord were able to be identified by gross examination, allowing proper selection of locations for tissue sampling. Subsequent histopathological evaluation was successfully performed with no apparent artifacts related with the TOC procedure. In addition, a combination of TOC and targeted CT angiography allowed feasible examination of the arterial occlusive lesion in the superior mesenteric artery, and when combined with micro-CT scanning it was useful for evaluating the lumen of the coronary artery with stent implantation. The results obtained so far indicated that TOC could complement routine forensic autopsy procedures when detailed evaluation of small lesions is required.

Drug delivery of 6-bromoindirubin-3\u2019-glycerol-oxime ether employing poly(d,l-lactide-co-glycolide)-based nanoencapsulation techniques with sustainable solvents

BackgroundInsufficient solubility and stability of bioactive small molecules as well as poor biocompatibility may cause low bioavailability and are common obstacles in drug development. One example of such problematic molecules is 6-bromoindirubin-3'-glycerol-oxime ether (6BIGOE), a hydrophobic indirubin derivative. 6BIGOE potently modulates the release of inflammatory cytokines and lipid mediators from isolated human monocytes through inhibition of glycogen synthase kinase-3 in a favorable fashion. However, 6BIGOE suffers from poor solubility and short half-lives in biological aqueous environment and exerts cytotoxic effects in various mammalian cells. In order to overcome the poor water solubility, instability and cytotoxicity of 6BIGOE, we applied encapsulation into poly(d,l-lactide-co-glycolide) (PLGA)-based nanoparticles by employing formulation methods using the sustainable solvents Cyrene™ or 400 g/mol poly(ethylene glycol) as suitable technology for efficient drug delivery of 6BIGOE.ResultsFor all preparation techniques the physicochemical characterization of 6BIGOE-loaded nanoparticles revealed comparable crystallinity, sizes of about 230 nm with low polydispersity, negative zeta potentials around − 15 to − 25 mV, and biphasic release profiles over up to 24 h. Nanoparticles with improved cellular uptake and the ability to mask cytotoxic effects of 6BIGOE were obtained as shown in human monocytes over 48 h as well as in a shell-less hen’s egg model. Intriguingly, encapsulation into these nanoparticles fully retains the anti-inflammatory properties of 6BIGOE, that is, favorable modulation of the release of inflammation-relevant cytokines and lipid mediators from human monocytes.ConclusionsOur formulation method of PLGA-based nanoparticles by applying sustainable, non-toxic solvents is a feasible nanotechnology that circumvents the poor bioavailability and biocompatibility of the cargo 6BIGOE. This technology yields favorable drug delivery systems for efficient interference with inflammatory processes, with improved pharmacotherapeutic potential.Graphical

Zwitterionic Polymer Coatings Enhance Gold Nanoparticle Stability and Uptake in Various Biological Environments.

Zwitterionic polymers are a class of materials that have demonstrated utility as non-fouling surfaces for medical devices and drug delivery vehicles. Here, we develop a synthesis protocol to produce zwitterionic polymers as coatings for gold nanoparticles and evaluate nanoparticle stability and biological function after exposure to various biological fluids. Thiol-functionalized polymethacryloyloxyethyl phosphorylcholine polymers (pMPC) were synthesized in nontoxic solvents via photoinitiated free radical polymerization with a radical addition-fragmentation chain transfer (RAFT) agent and coated onto gold nanoparticles. pMPC-coated nanoparticles exhibited reduced particle aggregation, improved suspension stability, and decreased protein adsorption upon exposure to serum and lung lavage fluid (BALF). Cell uptake in A549 cells was greater for pMPC-coated particles than uncoated particles after exposure to serum and BALF, with no observed cell toxicity, but pMPC-coated particles experienced higher levels of cell uptake after serum exposure than BALF exposure, suggesting that differences in the composition of the fluids result in differing impacts on particle fate. These zwitterionic polymers may serve as useful nanoparticle coatings to enhance particle stability and uptake in various biological environments.

Imidazolium-based ionic liquids as demulsifier for water-crude oil emulsion

Most of the crude oils in the world are produced as water-crude oil emulsions. Removal of water from the emulsions is one of the major issues in the industry and the process is completed before transportation and refining. One of the methods to remove water is through demulsification. In the present study, ionic liquids, non-volatile and non-toxic solvents, are used as demulsifiers. Three ionic liquids (ILs), namely 1-ethyl-3-methylimidazolium acetate (EMIM-AC), 1-butyl-3-methylimidazolium chloride (BMIM-Cl) and 1-butyl-3-methylimidazolium hydrogen sulfate (BMIM-HSO4), were evaluated to treat a heterogeneous mixture of crude oil and water. The bottle tests were conducted at 60 °C and salinity of 50,000 ppm. Response surface methodology (RSM) was used to study the effect of IL type, its concentration, and residence time towards demulsification efficiency. The developed correlation gave a high correlation coefficient, R2 of 0.924. Analysis shows that the IL concentration gives the highest influence on the demulsification efficiency, followed by the residence time and the type of ionic liquid. Among the three ILs investigated, 1000 ppm BMIM-HSO4 achieved the highest demulsification efficiency, where complete separation (100% demulsification efficiency) was attained within 30 min. BMIM-Cl achieved 72% efficiency after an hour while the EMIM-AC reached maximum separation after 52 min with 45% efficiency.

Enhancing the Thermostability of Engineered Laccases in Aqueous Betaine-Based Natural Deep Eutectic Solvents.

In recent years, natural deep eutectic solvents (NADESs) have gained increasing attention as promising nontoxic solvents for biotechnological applications, due to their compatibility with enzymes and ability to enhance their activity. Betaine-based NADESs at a concentration of 25 wt % in a buffered aqueous solution were used as media to inhibit thermal inactivation of POXA1b laccase and its five variants when incubated at 70 and 90 °C. All the tested laccases showed higher residual activity when incubated in NADES solutions, with a further enhancement achieved also for the most thermostable variant. Furthermore, the residual activity of laccases in the presence of NADESs showed a clear advantage over the use of NADESs’ individual components. Molecular docking simulations were performed to understand the role of NADESs in the stabilization of laccases toward thermal inactivation, evaluating the interaction between each enzyme and NADESs’ individual components. A correlation within the binding energies between laccases and NADES components and the stabilization of the enzymes was demonstrated. These findings establish the possibility of preincubating enzymes in NADESs as a facile and cost-effective solution to inhibit thermal inactivation of enzymes when exposed to high temperatures. This computer-aided approach can assist the tailoring of NADES composition for every enzyme of interest.

Magnetic Silica-Coated Picolylamine Copper Complex [Fe3O4@SiO2@GP/Picolylamine-Cu(II)]-Catalyzed Biginelli Annulation Reaction.

An efficient and heterogeneous novel magnetic silica-coated picolylaminecopper complex [Fe3O4@SiO2@GP/Picolylamine-Cu(II)] was synthesized, characterized, and employed as a magnetically recoverable nanocatalyst in Biginelli condensation for the preparation of biologically active 3,4-dihydropyrimidinones. Fe3O4@SiO2@GP/Picolylamine-Cu(II) was synthesized easily using chemical attachment of the picolylaminecompound on Fe3O4@SiO2@GP, followed by treatment with copper salt in ethanol under reflux conditions. Fe3O4@SiO2@GP/Picolylamine-Cu(II) was affirmed by various analyses such as Fourier transform infrared, thermogravimetric analysis, X-ray diffraction, vibrating-sample magnetometry, field-emission scanning electron microscopy, transmission electron microscopy, DLS, inductively coupled plasma, energy-dispersive X-ray spectrometry, X-ray photoelectron spectroscopy, and Brunauer-Emmett-Teller. The resulting catalyst system was successfully used in the Biginelli reaction through a variety of compounds such as aromatic aldehyde, urea, and ethyl acetoacetate under solvent-free conditions or ethylene glycol at 80 °C and yielded the desired products with high conversions with powerful reusability. The current approach was convenient and clean, and only 0.01 g of the catalyst could be used to perform the reaction. The easy work-up procedure, gram-scale synthesis, usage of nontoxic solvent, improved yield, short reaction times, and high durability of the catalyst are several remarkable advantages of the current approach. Also, the Fe3O4@SiO2@GP/Picolylamine-Cu(II) nanocatalyst could be recycled by an external magnet for eight runs with only a significant loss in the product yields.

Fabrication of ultrafiltration membranes from non-toxic solvent dimethylsulfoxide: Benchmarking of commercially available acrylonitrile co-polymers

In recent years, increased attention is given to sustainability and environmental safety of existing processes and materials. The membrane separation is considered as attractive alternative to conventional separation processes due to its greater energy efficiency and smaller carbon footprint. However, most organic solvents used for the production of polymeric membranes (DMF, DMAA, NMP), are hazardous and toxic; thus, non-toxic solvents like dimethylsulfoxide (DMSO) are considered nowadays as a perspective alternative to this solvents. The systematic study of the application of DMSO as “green” solvent for the fabrication of ultrafiltration membranes from the commercial polymer was carried out. Acrylonitrile homopolymer and six co-polymers of various composition and molecular weight were screened. It was revealed that the viscosity of the polymeric solution plays a major role in the resulting morphology and the performance of the membranes obtained. Regardless of the polymer origin and solvent nature, the studied membranes possessed finger-like porous structure if the viscosity of casting solution was lower than 42 Pa∙s, and the sponge-like porous structure at the viscosity greater than 78 Pa∙s. Analysis of the filtration data revealed that the replacement of traditional solvent DMF by non-toxic DMSO allowed obtaining the membranes with better overall performance in terms of pure water flux and rejection. The use of DMSO allowed to decrease the concentration of poly(acrylonitrile-co-itaconic acid) from 15 to 12 wt% in the spinning solution to achieve the same viscosity; and the resulting hollow fiber membrane demonstrated higher water flux and rejection compared to the one prepared from DMF.