Solvent Recycling Research Articles

Synthesis of Diarylethynes from Aryldiazonium Salts by Using Calcium Carbide as an Alkyne Source in a Deep Eutectic Solvent

AbstractAn efficient method for the synthesis of diarylethynes from aryldiazonium salts by using calcium carbide as an alkyne source at room temperature in a deep eutectic solvent is described. The salient features of this protocol are an inexpensive and easy-to-handle alkyne source, a nonvolatile and recyclable solvent, mild conditions, and a simple workup procedure.

Green chemistry approaches towards the design and synthesis of anti-infective fluoroquinolone derivatives

Fluoroquinolones are of pivotal interest for scientists because of their excellent pharmacological and pharmacokinetic profiles. They have a broad spectrum of antimicrobial activity and show several promising features such as, greater bioavailability, admirable tissue penetration and comparatively lower incidence of antagonistic and lethal effects. These have made the compounds highly desirable to combat several infectious diseases. Various synthetic conventions have been established to hasten the fluoroquinolone’s amination rate and to improve yield. Such methods have significant disadvantages including, costly reagents, usage of vast quantities of harmful solvents, excessive heat and sideways reactions. These drawbacks aren’t appropriate in current pharmaceutical market. Hence, it is highly desirable to develop a newer green and more efficient process for fluoroquinolones synthesis. Green chemistry methodology endeavours to achieve sustainability at the molecular level. The field of green chemistry has shown how chemists can design next-generation products and processes to make them more cost-effective while being virtuous for human health and the environment. This graphical review demonstrates the current developments in the synthesis of fluoroquinolones employing the principles of green chemistry by using the novel, recyclable and environmental-friendly catalysts and solvents.

Assessing health and environmental impacts of solvents for producing perovskite solar cells

Halide perovskites are poised as a game-changing semiconductor system with diverse applications in optoelectronics. Industrial entities aim to commercialize perovskite technologies because of high performance but also because this type of semiconductor can be processed from solution, a feature enabling low cost and fast production. Here, we analyse the health and environmental impacts of eight solvents commonly used in perovskite processing. We consider first- and higher-order ramifications of each solvent on an industrial scale such as solvent production, use/removal, emissions and potential end-of-life treatments. Further, we consider the energy of evaporation for each solvent, air emission, condensation and subsequent incineration, reuse or distillation for solvent recycling, and apply a full end-of-life analysis. For human health impact, we use the ‘USEtox’ method but also consider toxicity data beyond carcinogenic classifications. We find that dimethyl sulfoxide has the lowest total impact, by being the most environmentally friendly and least deleterious to human health of the solvents considered. The analysis of the effects of these solvents on human health and the environment provides guidance for sustainable development of this new technology. Perovskite solar cells could be a game-changing energy technology. However, the solvents involved during fabrication pose sustainability concerns. Here, the authors provide an analysis of human health toxicity and environmental implications of handling solvents, recommending dimethyl sulfoxide (DMSO) as the green choice for large-scale production.

Extraction of peroxidase from apple peel waste mediated by tween 80 reverse micelle system

Plants peroxidase is an important class of oxidoreductases. It exists widely in plants, animals and microorganisms, capable of catalyzing the oxidation of H2O2 phenols, vitamin C, nitrite, colorless dyes, indole and inorganic ion reaction. The reverse micelles extraction operation process is simple, continuous-operation, recyclable solvent, maintaining the native conformation of the protein. And it will not produce secondary pollution to the environment so that it has been gradually applied in the extraction and purification of the enzyme. Experimental operation of this paper was divided into the following two aspects: on the one hand, the selection of extraction technique and methods of detecting enzyme content and activity. We selected coomassie blue staining to determine enzyme content, while using ultraviolet spectrophotometry to resveratrol as a substrate for peroxidase activity assessment. On the other hand, the main aspect was how single factor affected reverse micelles extraction efficiency, including the aqueous phase pH, surfactant concentration and extraction time. By comparing difference of the recovery and purification of peroxidase between multiple different variables under same factors, we could get the optimum conditions: Tween 80 at a concentration of 0.30 mol/L, pH = 4.5, oscillation time of 20 min.

Unveiling Modifications of Biomass Polysaccharides during Thermal Treatment in Cholinium Chloride : Lactic Acid Deep Eutectic Solvent.

A deep analysis upon the chemical modifications of the cellulose and hemicelluloses fractions that take place during biomass delignification with deep eutectic solvents (DES) is lacking in literature, being this a critical issue given the continued research on DES for this purpose. This work intends to fill this gap by disclosing a comprehensive study on the chemical modifications of cellulose (microcrystalline cellulose and bleached kraft pulp) and hemicelluloses (xylans) during thermal treatment (130 °C) with cholinium chloride/lactic acid ([Ch]Cl/LA) at molar ratio 1 : 10, one of the best reported DES for biomass delignification. The obtained data revealed that [Ch]Cl/LA (1 : 10) has a negative impact on the polysaccharides fractions at prolonged treatments (>4 h), resulting on substantial modifications including the esterification of cellulose with lactic acid, shortening of fibers length, fibers agglomeration and side reactions of the hemicelluloses fraction (e. g., humin formation, lactic acid grafting). Wood delignification trials with [Ch]Cl/LA (1 : 10) at the same conditions also corroborate these findings. Moreover, the DES suffers degradation, including the formation of lactic acid derivatives and its polymerization. Therefore, short time delignification treatments are strongly recommended when using the [Ch]Cl/LA DES, so that a sustainable fractionation of biomass into high quality cellulose fibers, isolated lignin, and xylose/furfural co-production along with solvent recyclability could be achieved.

Correction to “Recycling of Superbase-Based Ionic Liquid Solvents for the Production of Textile-Grade Regenerated Cellulose Fibers in the Lyocell Process”

Correction to “Recycling of Superbase-Based Ionic Liquid Solvents for the Production of Textile-Grade Regenerated Cellulose Fibers in the Lyocell Process”

Quantification of N-methylmorpholine-N-oxide and its main degradation products by nuclear magnetic resonance spectroscopy

An important part of Lyocell fibers production is solvent recycling. Determining the content of the degradation products in the solvent will be helpful to select a reasonable solvent recovery process. However, a suitable method to simultaneously measure N-methylmorpholine-N-oxide and its main degradation products N-methylmorpholine and morpholine has not yet been reported, hence in this paper, a nuclear magnetic resonance spectroscopy method for quantitative analysis of N-methylmorpholine-N-oxide and its major degradation products was established. The feasibility of this nuclear magnetic resonance method was verified by using it to determine the contents of N-methyl morpholine-N-oxide, N-methylmorpholine, and morpholine in analytical samples and actual sample.

Continuous Industrial-Scale Centrifugal Partition Chromatography with Automatic Solvent System Handling: Concept and Instrumentation

Centrifugal partition chromatography (CPC) is an emerging separation technology in pharmaceutical and natural product purifications, reaching recently industrial-scale solutions. Because both the stationary and mobile phases are liquids in CPC, the solvent consumption of such separation processes is considered significant. Thus, automation is highly required in the preparation and recycling of the solvent mixtures for economical (i.e., continuous) CPC operation. Here, we report a feasible solution for this industrial issue, including the concept, algorithm, and instrumentation of solvent system handling. For majority of ternary solvent systems used in CPC separations, the linear correlation between the density and composition of the phases was recognized and utilized during the continuous solvent recycling. Hence, an efficient density-based composition adjustment algorithm was established in a mixer-settler unit using Coriolis flow meters for precise density monitoring of the upper and lower phases of the biphasic liquid system (BLS). In addition, a complete cascade consisting of a buffer, waste, a recycler (evaporator), and mixer-settler units was designed around the industrial-scale CPC device. The proof of concept was demonstrated by sequential industrial-scale CPC separations of a binary model mixture in the n-hexane/methanol/water (5/4/1, v/v/v) solvent system, followed by the purification of a crude steroid active pharmaceutical ingredient performed in the methyl isobutyl ketone/acetone/water (2/2/1, v/v/v) solvent system. The reproducibility of chromatographic performance and the productivity of the mixer-settler and evaporator units were satisfactory, enabling a robust and continuous operation of the developed separation process.

Recyclable deep eutectic solvent coupling sodium hydroxide post-treatment for boosting woody/herbaceous biomass conversion at mild condition

A novel recyclable deep eutectic solvent (DES) consisting of p-toluene sulfonic acid (p-TsOH) and choline chloride (ChCl) was developed for efficient woody poplar sawdust (PL) and herbaceous miscanthus (MC) conversion at mild condition. The extraction of leftover lignin on the surface of DES pretreated residues using NaOH solution at room temperature greatly improved the enzymatic hydrolysis efficiency. Near complete cellulose conversion of PL and MC residues were obtained with a degree of delignification and xylan removal over 90% at 100 °C within 40 min. The strong correlations between xylan (R2 = 0.95) and lignin (R2 = 0.82) removal with cellulose conversion were observed in MC as well as positive correlations (R2 > 0.77) in PL. The results demonstrated that the DES system coupling NaOH post-treatment was a promising method to achieve an economically feasible biomass conversion process, which was effective for both woody PL residues and herbaceous MC.

Comprehensive utilization of corncob for furfuryl alcohol production by chemo-enzymatic sequential catalysis in a biphasic system

A new process for the production of furfuryl alcohol from corncob was constructed by using deep eutectic solvents and whole cell catalysis in this paper. Firstly, the corncob was treated with deep eutectic solvents to convert the xylan into furfural, and then the pretreated corncob residue was enzymatically hydrolyzed to obtain a glucose-rich enzymatic hydrolysate, which was used to provide NADH for Bacillus coagulans NL01 during the process of furfural reduction. The furfural yield could reach 46% using the selected choline chloride-oxalic acid as catalysts and corncob as substrate under the optimized catalytic condition at 120 °C for 30 min. The final furfuryl alcohol yield of 20.7% was achieved with corncob as substrate. Moreover, this catalytic system realized the recycling of deep eutectic solvents three times, the high-value production of furfuryl alcohol, and the comprehensive utilization of corncob.

Modeling, simulation and optimization of the rotating packed bed (RPB) absorber and stripper for MEA-based carbon capture

Despite rising concern with climate change, carbon capture is yet to be implemented widely in the industry due to its size and cost. The rotating packed bed (RPB), a high gravity technology process, has been suggested to intensify the conventional packed bed. In this study, rigorous models of the RPB absorber and stripper for carbon capture are developed and implemented in the commercial simulator of gPROMS. The developed process models are validated with published steady-state experimental data and the entire carbon capture process comprising the RPB absorber, the RPB stripper, and other process units with solvent recycle is simulated. Initial designs of the rotating packed beds are suggested considering the flooding limit and capture rate. Then the steady-state optimal operation conditions minimizing the total energy of the MEA process with the intensified absorber and stripper are found and their behaviors are analyzed.

Analysis of reactor–separator processes for polymeric and oligomeric degradation products with controlled molar mass distributions

Integration of reaction and separation is attractive in production of biobased oligomers and short polymers from polysaccharides and proteins via catalytic degradation. The challenge lies in controlling the molar mass distribution. Theoretical analysis for process integration is performed for conventional CSTR, a multifunctional reactor, and reactor-separator-recycle processes. Closed-form solutions for the mass balance equations are obtained for coupled serial-parallel first-order reactions. The influence of the separators’ cut-off range and sharpness on the feasible operating parameter range and process performance is visualized. It is found that a membrane reactor may be less productive than a CSTR if total concentration is limited. An additional separator to recycle the solvent significantly improves purity and productivity. Solvent recycling decouples the feed rate and the residence time of the product molecules. To maximize purity and productivity, no product molecules should be retained in the reactor whereas the recycled solvent can be impure.

Iodine-catalyzed synthesis of β-uramino crotonic esters as well as oxidative esterification of carboxylic acids in choline chloride/urea: a desirable alternative to organic solvents

Iodine-mediated selective synthesis of β-uramino crotonic esters was achieved via the reaction of β-dicarbonyls and urea at room temperature. Choline chloride/urea mixture, as an eco-friendly, cheap, non-toxic, and recyclable deep eutectic solvent (DES), was employed as sustainable media as well as reagent at the same time in these transformations. Some derivatives of β-uramino crotonic esters were synthesized with good to high yields without a tedious work-up. The process could be done to synthesize the above-mentioned compounds in gram scale. Moreover, oxidative cross-esterification of carboxylic acids with alkyl benzenes was carried out in the above-mentioned DES by the employment of tetrabutylammonium iodide (TBAI) as the catalyst and tert-butyl hydroperoxide (TBHP) as the oxidant at 80 °C. DES/TBAI system was reused up to five consecutive times. Iodine-catalyzed C–N and C–O bond formation in choline chloride/urea as a green solvent under the mild reaction conditions. Providing the clean procedure toward synthesis of β-uramino crotonic esters and benzylic esters.

Recycling of Superbase-Based Ionic Liquid Solvents for the Production of Textile-Grade Regenerated Cellulose Fibers in the Lyocell Process

Ioncell is a Lyocell based technology for the production of man-made cellulose fibers. This technology exploits the intrinsic dissolution power of superbase-based ionic liquids (ILs) toward cellulo...

Sequential fractionation of sugarcane bagasse using liquid hot water and formic acid-catalyzed glycerol-based organosolv with solvent recycling

A fractionation scheme for lignocellulosic biomass where major constituent biopolymers are recovered in applicable forms is essential for integrated biorefinery. In this study, a sequential two-step fractionation of sugarcane bagasse using liquid hot water followed an organic acid-catalyzed aqueous glycerol-based organosolv process was developed. Under optimal conditions, 66.1% of the hemicellulose was recovered as saccharides by the acid-catalyzed hydrothermal step. Formic acid was superior to H2SO4 and HNO3 as a catalyst for the subsequent organosolv step using aqueous glycerol in terms of delignification efficiency and selectivity, resulting in a maximum of 78.3% lignin recovery after acetone extraction with > 90% purity and better conservation of aromatic subunit structure according to 2D-NMR. The majority of cellulose (86.4%) was retained as a solid with high purity (74.8%) and enzymatic digestibility, resulting in 78.2% glucose recovery. The formic acid-aqueous glycerol-spent liquor could be recycled for at least four consecutive batches with no significant decrease in product yield or selectivity. The work represents an efficient sequential process for fractionation of lignocellulose-derived components which allowed solvent recycling and recovery of high-purity lignin with conserved subunit structure. The separated product streams are suitable for valorization in biorefinery. Graphical abstract

Tuning Microenvironment of Quaternary Ammonium Salt and Tertiary Amine Bifunctionalized Polyacrylonitrile Fiber for Cooperatively Catalyzed Aza-Michael Addition

A series of novel polyacrylonitrile fiber catalysts modified with different ratio of quaternary ammonium salt (QA) to tertiary amine (TA) were screened for heterogeneously catalyzed aza-Michael addition in water. The best catalyst was found to be PANPQ-1F with a QA:TA ratio of 1:1, which can lead to high yield, excellent selectivity of solvent and great recyclability under optimized conditions. The special microenvironment of hydrophilic inner layer and hydrophobic surface layer of PANPQ-1F is conducive to the leaving of the product and the high conversion of the reaction. Based on the fact that appropriate microenvironment combined with the catalytic sites promoted the reaction, cooperative effect of QA and TA in the microenvironment of PANPQ-1F catalyst was proposed.

Environmentally Benign and Large-Scale Synthesis of Monodisperse Oleate-Protected Silver Nanoparticles in Ethanol

An environmentally benign solvothermal process was introduced to synthesize monodisperse silver nanoparticles (Ag NPs). Silver nitrate (AgNO3) was reduced by ethanol which was also used for recyclable solvent. The as-synthesized Ag NPs were stabilized by oleate. Effects of reaction temperature, reaction time, AgNO3 concentration as well as molar ratio of sodium oleate and AgNO3 on the formation and surface plasmon resonance (SPR) were determined by means of UV–Vis spectrophotometer. TEM and XRD were used to characterize the size, morphology and crystalline structure of Ag NPs. The excessive AgNO3 over sodium oleate and high concentration of AgNO3 are favorable for the synthesis of monodisperse Ag NPs in large scale. The characteristic SPR absorption of Ag NPs centers at ca. 430 nm despite of reaction temperature, reaction time and even AgNO3 concentration. The nucleation and growth of Ag NPs completed in a very short period of time, showing the high efficiency of our synthetic route for the synthesis of uniform Ag NPs.

Energy management in distillation preheat systems

Economizers in preheat systems represent a method for process intensification that has been widely applied. Despite its long history, control problems have been reported and attributed to thermal interaction and feedback. A recent paper studied the use of several heat-exchanger configurations for preheating streams in an extractive distillation column with a sidestream. The hot solvent recycle stream can be used to preheat the fresh feed to the extractive column, or it can be used to preheat the liquid sidestream from the extractive column that is fed to the solvent recovery column. A third alternative that is the most energy efficient uses two economizers in series, the first preheating the sidestream and the second preheating the fresh feed. However, dynamic controllability issues were experienced that were attributed to positive feedback of thermal energy. A heat-exchanger bypass control structure was proposed to handle the problem.This paper suggests that the problem occurs because of partial vaporization of the column feeds in the economizers, which can be eliminated by keeping the pressures in the economizers high enough to maintain liquid-phase sensible heat transfer. Process intensification methods can only produce the desired efficiency results if the process is effectively and safely controlled.

Temperature-responsive deep eutectic solvents as green and recyclable media for the efficient extraction of polysaccharides from Ganoderma lucidum

Recently, more and more attention has been paid to the green and recyclable deep eutectic solvents (DESs) in the extraction and separation field. In this study, nine temperature-responsive deep eutectic solvents (TRDESs) were prepared and developed to extract polysaccharides from Ganoderma lucidum (G. lucidum). The polysaccharides were extracted into a homogeneous solution above the upper critical solution temperature (UCST) of TRDESs. The factors influencing the solid-liquid extraction were investigated, including type and concentration of TRDESs, liquid-solid ratio, extraction temperature, extraction time, and pH. Then, two phases formed below the UCST of TRDESs with the polysaccharides being recovered in the aqueous phase and TRDESs being recycled and reused. The cyclic stability of TRDESs was evaluated by studying the extraction ability of extractant, structure and activity of polysaccharides after several recycles of TRDESs. Finally, the hydrogen bond donors (HBDs) and hydrogen bond acceptors (HBAs) of TRDESs can be recovered by using carbon dioxide and nitrogen after the cyclic tests. Further studies of density functional theory (DFT) calculations proved that the hydrogen bond interaction was the main factor affecting this extraction, and meanwhile the HBAs played the dominant role in this process. This study gives some guidance for the exploration and application of recyclable DESs for the green and sustainable extraction of various bioactive compounds from plant resources.

Phenolic compounds from virgin olive oil obtained by natural deep eutectic solvent (NADES): effect of the extraction and recovery conditions.

Environmentally friendly natural deep eutectic solvents (NADES) have been shown to efficiently extract a wide range of phenolic compounds from virgin olive oil (VOO). The objective of this work was to optimize the yield of olive oil phenols extracted by NADES based on xylitol/choline choride (Xyl/ChCl). Different extraction and recovery conditions were investigated, including the effect of different extraction operating parameters (temperature, time, VOO:NADES ratio) and subsequent recovery conditions (XAD resin height, wash-water and eluent volume and pH). The highest concentration of phenols (555.36mg/kg VOO) was obtained from extraction at 40°C for 1h, with a 1:1 ratio, using an adsorption resin XAD-16 with bed height of 10cm, 250mL acidified wash-water and 300mL EtOH 100% as eluent. No statistically significant loss of the sum of phenolic compounds was observed when compared with the concentration values obtained by direct analysis in HPLC without the elimination of NADES. Additionally, a sequential desorption with different concentration of ethanol was used to determine the effect of the solvent concentration on polyphenol yield. Polar compounds, such as hydroxytyrosol and tyrosol, were recovered at 81.7% and 83.6%, respectivelywith 50 and 80% ethanol; however, 100% ethanol was required for the complete elution of oleacein (3,4-DHPEA-EDA) and oleocanthal (p-HPEA-EDA). In this paper we present an effective process for the extraction of polyphenols from VOO by NADES for direct analysis in HPLC and for the recovery and concentration of polyphenols by removing the solvent (NADES) with no losses of yield and solvent recycling.