Acid Solvent System Research Articles

Efficient Extraction and Analysis of Wheat Straw Lignin by Response Surface Methodology

To enhance the high-value utilization of straw waste and achieve efficient lignin extraction, wheat straw was selected as the feedstock for investigating the effects of reaction temperature, reaction time, solid–liquid ratio, and formic acid concentration on lignin yield using a formic acid/acetic acid solvent system. A single-factor experimental design was initially employed, followed by optimization using the response surface methodology. Additionally, a kinetic model was developed to describe lignin extraction kinetics in the formic acid/acetic acid system. The structural characteristics and thermal stability of the extracted lignin were analyzed via FTIR, UV spectroscopy, and TGA. The findings indicate that increasing reaction temperature, reaction time, solid–liquid ratio, and formic acid content all significantly enhanced lignin extraction yield from wheat straw, with the primary influencing factors being reaction temperature > solid–liquid ratio > reaction time > formic acid content. The optimal extraction conditions were identified at a reaction temperature of 90 °C, a reaction time of 3.5 h, a solid–liquid ratio of 1:16.5, and a formic acid content of 86.2 wt.%, yielding a lignin content of 79.83%. The analytical results demonstrated that the extracted lignin preserved the structural integrity of the original lignin and exhibited good thermal stability.

Pretreatment of shrimp shells with an acidic deep eutectic solvent system for chitin extraction and its enhanced performance as a carrier for immobilized lipase

Existing methods for chitin extraction usually produce substantial waste, which poses ecological hazards. Natural deep eutectic solvent (NADES) offers a promising one-step pretreatment alternative, replacing the resource-intensive demineralization (DM) and deproteinization (DP) process. Hence, in this study, the influence of various acidic NADES, on achieving a simplified one-step DM and DP in the chitin extraction process was investigated. The study yielded chitin with 87.73 % purity, and microstructural analysis showed that NADES pretreatment minimally affected chitin quality without deacetylation. In addition, chitin extracted using choline chloride-oxalic acid as a carrier displayed excellent performance in the immobilization of Geobacillus thermocatenulatus lipase 2 (GTL2) because of obvious Ca2+ activation effect. This process contributed to enhancement of immobilized enzyme activity. The immobilized GTL2 showed excellent hydrolytic capabilities, with its highest activity reaching 547.80 ± 20.62 U/mg, significantly better than the five commercial lipases that exhibited <40 % of the enzyme activity. Furthermore, the hydrolytic capacity of immobilized GTL2 was notably high for 4-nitrophenyl butyrate, measuring 935.47 ± 51.60 U/mg. This study provided a constructive approach for the one-step pretreatment of shrimp shells with organic acid-based NADES to isolate and purify chitin and its potential application as an immobilized carrier to enhance enzyme activity.

Primena vodenih eutektičkih rastvarača za hemijsku valorizaciju otpadnog mulja - određivanje mineralnog sadržaja

Sewage sludge is a by-product of municipal wastewater treatment processes with significant soil-forming and fertilizing characteristics. However, if sewage sludge contains heavy metals, it can negatively affect the soil environment. The accumulation of heavy elements in the soil can negatively affect the circulation of elements in the natural environment, regarding plants, animals, and humans. The primary sources of heavy metals in human and animal food are plants, which are also the primary consumers of mineral nutrients from soil and water. Even a very small amount of heavy metals in the body can create metabolic problems, reduced body functions, and compromised immune and enzymatic processes, all of which contribute to various diseases and may even cause death. The aim of this study was to find a suitable system for mineral extraction from the municipal sewage sludge after water purification, collected from the wastewater treatment plant in Vlasotince, so the real composition of sewage sludge could be obtained. For that purpose, different aqueous deep eutectic solvents were applied: choline chloride:lactic acid (ChCl:LA), choline chloride:urea (ChCl:U), choline chloride:glycerol (ChCl:G), choline chloride:propylene glycol (ChCl:PEG), choline chloride:citric acid (ChCl:CA), and choline chloride:ethylene glycol (ChCl:EG).The concentrations of minerals after wet digestion were determined by Inductively Coupled Plasma - Optical Emission Spectrometry (ICP-OES). The results showed that the highest amounts of minerals, especially Ca, P, and Fe, were extracted using aqueous acidic deep eutectic solvent systems (ChCl:LA and ChCl:CA). Also, the mineral composition of sewage sludge indicates the possibility of its use as a significant soil fertilizer supplement.

In vitro release study of electrospun poly(ε-caprolactone)/gelatin nanofiber mats loaded with 5-fluorouracil

The electrospinning process was used to successfully encapsulate an anticancer drug, 5-fluorouracil (5-FU), into poly(ε-caprolactone)/gelatin (Gel) nanofiber mats (5-FU-PCL/Gel NFs). Nanofibers are recognized to be potential carriers for the delivery of anticancer drugs. One of the safest solvent systems for making PCL/Gel NF mats is the formic acid/acetic acid (FA/AA) solvent system. A compound solution jet was drawn from a customized coaxial spinneret using a high potential electric field of 20 kV. The loading of 5-FU with three different concentrations (5, 10, and 15 wt.%) improved PCL stabilization in the FA/AA system. The miscibility of the blended polymers in the electrospun nanofibers mats and 5-FU being well distributed in the nanofiber matrix was investigated using X-ray diffraction (XRD). In vitro 5-FU release from electrospun PCL/Gel NF mats revealed sustained release from the nanofiber mats, whereas slower release was found when higher concentrations of 5-FU were used. The produced electrospun PCL/Gel NF mats were studied by SEM, FTIR, TGA, and DSC. According to a study on drug release kinetics, 5-FU was released from PCl/Gel NFs in a diffusion-controlled pattern.

Phytochemical Investigation and Thin Layer Chromatography of Methanol Extract of Psoralea corylifolia and Emblica officinalis Leaves

The current study focuses on phytochemical screening of Psoralea corylifolia and Emblica officinalis leaf extracts in methanol solvent. The antibacterial compounds found in both leaf extracts of Psoralea corylifolia and Emblica officinalis plants were investigated using phytochemical studies. The extracts contained flavonoids, terpenoids, tannins, alkaloids, saponins, and phenolic chemicals, according to preliminary phytochemical screening. The solvent systems of toluene: ethyl acetate: methanol (24:5:2) and chloroform: ethyl acetate: acetic acid (50:50:1) yielded the most phytochemicals from methanolic extracts of Psoralea corylifolia and Emblica officinalis plants, respectively. On TLC plates, these chemicals were separated, resulting in the discovery of different spots in both leaf extracts. The Rf values of methanol extract of P. corylifolia run under toluene: ethyl acetate: methanol (24:5:2) solvent system was 0.12, 0.19, 0.30, 0.41, 0.53, 0.65, 0.77, 0.84, 0.89, and 0.92, respectively, while Rf values of methanol leaf extract of E. officinalis run under chloroform: ethyl acetate: acetic acid (50:50:1)solvent system was 0.23, 0.31, 0.41, 0.64, 0.76 and 0.88 respectively. The results of the investigation will be used to confirm the proper identification of antibacterial fractions from P. corylifolia and E. officinalis crude plant extracts by GC-MS. The optimum solvent for extracting antibacterial components from P. corylifolia and E. officinalis leaves was methanol.

THIN LAYER CHROMATOGRAPHIC TECHNIQUES FOR DETECTION OF SUDAN DYES IN PALM OIL

Sudan dyes I, II, III &amp; IV are synthetic, oil-soluble, red-coloured azo dyes. These dyes are suspected genotoxic carcinogens and have been used in the adulteration of palm oil products. Many experimental studies on animal specimen have confirmed the formation of tumour due to the presence of different Sudan dyes in food products. In this study, a Simple Thin Layer Chromatographic method is described for the qualitative detection of Sudan-I, II, III &amp; IV in palm oil gotten from different markets. The study includes extraction of sample, preparation of Thin Layer Chromatography (TLC) plates, Separation, detection and visualization of dyes on TLC plates. The dyes were extracted with solvent Acetonitrile. Sample extracts were decanted and analysed by simple thin layer chromatography in hexane, chloroform and acetic acid solvent system. The chromatograms of samples and standards were stained with Iron (ii) chloride stain and further evaluated in term of Rf values. Out of the five samples analysed the Rf values of the colouring spots from the three samples L2, L3 and L4, matched the standards (S2). It is therefore, concluded that samples L2, L3 and L4 contain Sudan IV dye. Without using any derivation, the limit of detection (18mg/L for S2 (Sudan IV dye) and 10mg/L for SI (Sudan III dye) was determined by visually determining if a spot was visible or not at a certain concentration of standard dye.&#x0D;

Research of &lt;I&gt;Rhodiola rosea&lt;/I&gt; Rhizomes and Roots Using High Performance Thin Layer Chromatography

Introduction. The research results obtained through the analysis of different varieties of Rhodiola rosea rhizomes and roots using high-performance thin layer chromatography (HPTLC), grown in the Saint-Petersburg State Chemical-Pharmaceutical University (SPCPU) medicinal plants nursery garden, are represented.Aim. To carry out a comparative analysis of Rhodiola rosea rhizomes and roots samples, grown in the SPCPU medicinal plants nursery using HPTLC.Materials and methods. HPTLC analysis was performed on a CAMAG device (Switzerland), using MERCK HPTLC silica gel 60 F 254, 20 × 10 cm plates. Extracts were obtained from raw materials using an ultrasonic bath "Sapphire-4.0 TTC" (Russia). The Rhodiola rosea rhizomes and roots were harvested in the SPCPU medicinal plants nursery garden (Leningrad Region, Vsevolozhsk district, Priozerskoe Highway, 38 km) in August 2019.Results and discussion. In the course of the research, extracts from Rhodiola rosea rhizomes and roots were obtained using 70 % ethyl alcohol and methyl alcohol as extractants. The extracts were investigated by HPTLC in ethyl acetate – methanol – water – formic acid (77 : 13 : 10 : 2) solvent system. After scanning densitometric analysis at 254 nm, the much better separation of methanol extracts in this solvent system was found than ethanol extracts. The densitograms of individual tracks were compared with each other in order to identify samples of Rhodiola rosea rhizomes and roots with a higher biologically active compounds content. As a result of the comparison of 18 samples tracks of the Rhodiola rosea rhizomes and roots (the extractant was ethyl alcohol 70 %), samples № 6 and 17 have been proposed as promising for further research and cultivation.Conclusion. As a result of the analysis of alcohol extracts from Rhodiola rosea rhizomes and roots by HPTLC, the samples 6 (Tomsk, Russia) and 17 (Valla Di Aposta/Hirvos varieties, country of origin – Italy/Finland) were found to have a higher content of biologically active compounds.

Oxidation-extraction desulfurization of fuel with a novel green acidic deep eutectic solvent system

Deep eutectic solvents (DESs) have important application prospects in fuel desulfurization. A novel dual Brønsted acidic DES was proposed and successfully synthesized for one-pot oxidation-extraction desulfurization process, in which a green and harmless choline chloride (ChCl) was used as hydrogen bond acceptor, p-toluenesulfonic acid (TsOH) and oxalic acid (OA) were used as hydrogen bond donors to provide acidic groups. The results showed that the new DESs (ChCl/2TsOH/0.2OA) had the excellent desulfurization efficiency due to the strong acidity based on the synergistic effect between the two acidic groups. The content of benzothiophene (BT), dibenzothiophene (DBT), and 4,6-dimethyldibenzothiophene (4,6-DMDBT) could be reduced to 8.82 ppm (120 min), 1.23 ppm (90 min), and 7.75 ppm (90 min), respectively. Electron spin resonance and radical capture experiments showed that superoxide radicals (·O2–) were the main oxidizing agents. The possible oxidation-extraction pathway was that DBT was extracted from oil phase into DES phase, and the DES was converted to peroxy acid in the presence of ·O2–, then the extracted DBT in DES phase was oxidized to high polar sulfone. It can be regenerated and recycled by simple water washing. To improve dispersion and treatment efficiency, reduce the amount of DESs, the viscosity of DESs was adjusted by using sulfolane as the dilute, which could significantly reduce the operation time and enhance the desulfurization effect. The content of BT, DBT, and 4,6-DMDBT could be reduced to 12.20, 2.21, 7.38 ppm only need 45, 5, and 15 min, correspondingly. The novel green DES can provide theoretical support and technical guidance for deep fuel desulfurization.

Two Novel Co-Crystals of Naproxen: Comparison of Stability, Solubility and Intermolecular Interaction.

Two novel co-crystals of naproxen (NPX) were designed and prepared at a stoichiometric ratio of 1:1, namely, naproxen–caprolactam (NPX–CPL) and naproxen–oxymatrine (NPX–OMT). The characteristics of the co-crystals were evaluated in terms of stability and solubility studies. In terms of solubility, in four kinds of solvent systems with different pH, the solubility of NPX–OMT was significantly improved compared with that of NPX, whereas the NPX–CPL showed advantages in acidic solvent systems, indicating that the co-crystals can be applied to concoct preparations depending on therapeutic purposes. Furthermore, the experimental results of the thermal analysis showed that the co-crystal NPX–OMT had better thermal stability than the co-crystal NPX–CPL. Finally, as a complement to the single crystal X-ray diffraction (SC XRD) method, the theoretical calculation based on density functional theory (DFT) was also used to reveal the intermolecular interaction of the co-crystals at the molecular level and visually display the difference between them.

Versatile acid solvents for pristine carbon nanotube assembly.

Chlorosulfonic acid and oleum are ideal solvents for enabling the transformation of disordered carbon nanotubes (CNTs) into precise and highly functional morphologies. Currently, processing these solvents using extrusion techniques presents complications due to chemical compatibility, which constrain equipment and substrate material options. Here, we present a novel acid solvent system based on methanesulfonic or p-toluenesulfonic acids with low corrosivity, which form true solutions of CNTs at concentrations as high as 10 g/liter (≈0.7 volume %). The versatility of this solvent system is demonstrated by drop-in application to conventional manufacturing processes such as slot die coating, solution spinning continuous fibers, and 3D printing aerogels. Through continuous slot coating, we achieve state-of-the-art optoelectronic performance (83.6 %T and 14 ohm/sq) at industrially relevant production speeds. This work establishes practical and efficient means for scalable processing of CNT into advanced materials with properties suitable for a wide range of applications.

A novel virtual sample generation method based on a modified conditional Wasserstein GAN to address the small sample size problem in soft sensing

In the modern chemical industry process, soft sensing has been widely used. However, the lack of valid and sufficient data has made it difficult to apply advanced soft sensor modeling methods to realistic scenarios. In this paper, a novel soft sensing method based on deep learning is proposed to handle the problem of small data. Aiming at handling the issue of small sample size, a novel virtual sample generation method embedding a deep neural network as a regressor into conditional Wasserstein generative adversarial networks with gradient penalty (rCWGAN) is presented. In rCWGAN, conditional variables are introduced to make the training supervised and a dual training algorithm is specially designed. With the advanced structure and the designed training algorithm, rCWGAN has powerful sample generation capabilities and can well predict quality variables. Finally, an experiment on the purified terephthalic acid (PTA) solvent system is carried out for the validation of the presented rCWGAN. The simulation results indicate that the presented rCWGAN has good sample approximation ability and acceptable prediction accuracy with the small sample size task.

A modified ionization difference UV–vis method for fast quantitation of guaiacyl-type phenolic hydroxyl groups in lignin

An ionization difference UV–Vis method (Δε-spectrum method) is the most potentially simple method for fast quantitation of phenolic hydroxyl groups (ph-OH) in lignin. However, the underestimated results were calculated from the conventional Δε-spectrum method using one- or two-point wavelengths measurement. In this study, a modified Δε-spectrum method using multi-point wavelengths measurement was developed and the negative absorbance was also considered. Four main typical lignin models, e.g. vanilla alcohol, 5-5 biphenyl, stilbenoid and vanillin, were applied as the guaiacyl-type (G-type) phenolic models for the determination of ph-OH by the modified Δε-spectrum method. The 2-methoxyethanol/water/acetic acid = 8/2/0.2 (V/V/V) was used as the acidic solvent system and the 2-methoxyethanol/0.2 M NaOH solution = 1/9 (V/V) was used as the alkaline solvent system. The ph-OH contents in the spruce milled wood lignin (SMWL) and the spruce Kraft lignin (SKL) were respectively quantified by the modified Δε-spectrum method as 1.078 and 4.348 mmol/g, which were comparable to the counterparts determined by 31P Nuclear Magnetic Resonance Spectroscopy (31P NMR). The results revealed that the modified Δε-spectrum method can provide more accurate and reliable results compared to the conventional method.

The influence of solvent composition on the coordination environment of the Co/Mn/Br based para-xylene oxidation catalyst as revealed by EPR and ESEEM spectroscopy

The industrially important para-xylene oxidation reaction, based on a Co/Mn/Br catalyst, operates in a water/acetic acid (H2O/AcOH) solvent system.

Novel multimodal data fusion soft sensor modeling framework based on meta-learning networks for complex chemical process

Data-driven soft sensor has been widely used in industrial processes. However, complex industrial processes all exhibit nonlinear and multimodal characteristics due to varying operating conditions. Multimodal data characteristics will cause the deterioration of soft sensor performance. Therefore, in this article, a modified Model-Agnostic Meta-Learning (MAML) based on K-Means (KM) is proposed. Firstly, the KM method is introduced to cluster the multimodal processed data, and then extract the clustered data to form multiple tasks. After that, MAML method is adopted to train a group of initialization parameters. The sum of each task's loss function is introduced to adjust the initial parameters by one or more steps of gradient. The proposed model is finally applied and verified in the Purified Terephthalic Acid (PTA) solvent system. Compared to some conventional methods, the prediction accuracy is improved by more than 70%. The result demonstrates the superiority in the proposed method.

Facile Synthesis of Solubilizing a Group-Free, Solution-Processable p-Type Ladder Conjugated Polymer and Its Thermoelectric Properties.

Here we report the synthesis of a new solubilizing group-free, solution-processable p-type ladder conjugated polymer, 6H-pyrrolo[3,2-b:4,5-b']bis[1,4]benzothiazine ladder (PBBTL) polymer by using a polyphosphoric acid (PPA) and phenylphosphonic acid (PhPO3H2) 1:1 binary acid solvent system together with careful control of reaction kinetics. With a good intrinsic viscosity of 3.69 dL/g in methanesulfonic acid (MSA), good quality PBBTL films can be obtained via spin-coating. Intrinsic thin film properties and thermoelectric performance of PBBTL were evaluated, making it the second solubilizing group-free, solution-processable ladder-type conjugated polymer after BBL to be used for thin-film polymer electronics. While our preliminary thermoelectric performance of the FeCl3-doped PBBTL films is modest, we believe that many opportunities lie ahead for PBBTL and hope that its successful synthesis using the new PPA:PhPO3H2 binary acid solvent system will inspire synthetic organic chemists to relook into solubilizing group-free, solution-processable ladder-type conjugated polymer systems.

Investigating Antiarthritic Potential of Nanostructured Clove Oil (Syzygium aromaticum) in FCA-Induced Arthritic Rats: Pharmaceutical Action and Delivery Strategies.

The combined application of clove oil in a lipid nanocarrier opens a promising avenue for bone and joints therapy. In this study, we successfully developed a tunable controlled-release lipid platform for the efficient delivery of clove oil (CO) for the treatment of rheumatoid arthritis (RA). The ultra-small nanostructured lipid carriers co-loaded with CO (CONCs) were developed through an aqueous titration method followed by microfluidization. The CONCs appeared to be spherical (particle size of 120 nm), stable (zeta potential of −27 mV), and entrapped efficiently (84.5%). In toluene:acetone:glacial acetic acid (90:9:1 percent v/v/v) solvent systems, high-performance thin layer chromatography (HPTLC) analysis revealed the primary components in CO as eugenol (RF = 0.58). The CONCs greatly increased the therapeutic impact of CO in both in vitro and in vivo biological tests, which was further supported by excellent antiarthritic action. The CONC had an antiarthritic activity that was slightly higher than neat CO and slightly lower than standard, according to our data. The improved formulation inhibited serum lysosomal enzymes and proinflammatory cytokines while also improving hind leg function. This study provides a proof of concept to treat RA with a new strategy utilizing essential oils via nanodelivery.

5-[(1,3-Dimethyl-5-oxo-2-sulfanylideneimidazolidin-4-yl-idene)amino]-2-methyl-isoindoline-1,3-dione.

The title N,N-di-methyl-thio-hydantoin containing an N-methyl-ated pthalimide group, C14H12N4O3S, arose from an unexpected reaction in a deep eutectic di-methyl-thio-urea-tartaric acid solvent system. The mean planes of the ring systems are twisted at an angle of 73.84 (17)°. In the crystal, weak C-H⋯O hydrogen bonds connect the mol-ecules.

Electrospun Cellulose Acetate Nanofiber Morphology and Property Derived from CaCl2-Formic Acid Solvent System

Background: Electrospun Cellulose Acetate (CA) nanofibrous membrane can be used in many areas such as biomedicine, water treatment. However, due to the strong hydrogen-bond interaction, the rare solvent can dissolve the CA and the resulting CA nanofibrous membranes always show bad morphology and poor performance. Aims: To research the effect of CaCl2-Formic acid (CaCl2-FA) solvent system on the morphology and structure of CA nanofibrous membrane. Methods: CA nanofibrous membrane was fabricated with a two-step dissolution method using the first step of CaCl2-FA solvent system followed by the second step of FA solvent solely. Subsequently, the CA nanofibrous membrane morphology and structure property were systematically investigated. Results and Conclusion: The results show that the CaCl2-FA can dissolve the CA efficiently. Additionally, the regenerated CA nanofibers are well-formed under all the CA concentrations with controlling fiber diameter ranging from 224.9 ± 38.6 nm to 367.8 ± 80.4 nm. The results suggest that this two-step dissolution method can be an effective and alternative approach to dissolve CA and regenerate CA nanofibrous membrane.

Integrating virtual sample generation with input-training neural network for solving small sample size problems: application to purified terephthalic acid solvent system

Integrating virtual sample generation with input-training neural network for solving small sample size problems: application to purified terephthalic acid solvent system

Effects of amino acid additives on protein solubility - insights from desorption and direct electrospray ionization mass spectrometry.

Naturally occurring amino acids have been broadly used as additives to improve protein solubility and inhibit aggregation. In this study, improvements in protein signal intensity obtained with the addition of L-serine, and structural analogs, to the desorption electrospray ionization mass spectrometry (DESI-MS) spray solvent were measured. The results were interpreted at the hand of proposed mechanisms of solution additive effects on protein solubility and dissolution. DESI-MS allows for these processes to be studied efficiently using dilute concentrations of additives and small amounts of proteins, advantages that represent real benefits compared to classical methods of studying protein stability and aggregation. We show that serine significantly increases the protein signal in DESI-MS when native proteins are undergoing unfolding during the dissolution process with an acidic solvent system (p-value = 0.0001), or with ammonium bicarbonate under denaturing conditions for proteins with high isoelectric points (p-value = 0.001). We establish that a similar increase in the protein signal cannot be observed with direct ESI-MS, and the observed increase is therefore not related to ionization processes or changes in the physical properties of the bulk solution. The importance of the presence of serine during protein conformational changes while undergoing dissolution is demonstrated through comparisons between the analyses of proteins deposited in native or unfolded states and by using native state-preserving and denaturing desorption solvents. We hypothesize that direct, non-covalent interactions involving all three functional groups of serine are involved in the beneficial effect on protein solubility and dissolution. Supporting evidence for a direct interaction include a reduction in efficacy with D-serine or the racemic mixture, indicating a non-bulk-solution physical property effect; insensitivity to the sample surface type or relative placement of serine addition; and a reduction in efficacy with any modifications to the serine structure, most notably the carboxyl functional group. An alternative hypothesis, also supported by some of our observations, could involve the role of serine clusters in the mechanism of solubility enhancement. Our study demonstrates the capability of DESI-MS together with complementary ESI-MS experiments as a novel tool for understanding protein solubility and dissolution and investigating the mechanism of action for solubility-enhancing additives.