Aqueous Na2CO3 Research Articles

5‐Ammonium‐4,4‐dimethylvaleryl (Amv) Group: Generation from Acryloyl Group through Decatungstate‐Catalyzed C(sp3)−H Addition and Removal by Base‐Triggered Cyclization

AbstractThe 5‐ammonium‐4,4‐dimethylvaleryl (Amv) group was generated by conversion of acryloyl group through decatungstate‐catalyzed addition of C(sp3)−H bond of i‐BuNH2⋅HCl under the irradiation of UV light (365 nm or 405 nm). Treatment of Amv‐protected alcohols and anilines with aqueous Na2CO3 promoted the efficient deprotection of Amv. This is a unique method for the efficient removal of acryloyl groups from phenols, alcohols, and anilines. The selective removal of acryloyl groups through Amv in the presence of another acetyl or benzoyl group was demonstrated. The base‐triggered intramolecular cyclization of Amv was monitored by the release of a fluorescent molecule, and it was found that cyclization by Na2CO3 was very rapid (within 1 min) and that some weak bases such as 2,6‐lutidine are sufficient to promote cyclization.

SPECTRAL AND PHOTOPHYSICAL CHARACTERISTICS OF ASYMMETRIC POLYMETHINE DYES IN POLYURETHANE MATRICES

Here the composite polymer sorbent hydrogels were synthesized by in situ technique via free radical polymerization of acrylamide (AAm), 2-hydroxyethyl methacrylate (2HEMA) and N,N’-methylene-bis(acrylamide) crosslinker mixture in the presence of as-prepared dispersion of nickel-aluminum layered double hydroxide (NiAl-LDH). A content of active NiAl-LDH filler in the polymer matrix was varied in a range of 30 – 70 wt.%. It was found a high filler content suppresses a molecular mobility of copolymer matrix chains and reduces a beginning of glass transition temperature of the polymer constituent. The results of thermal analysis of polymer composites demonstrate a high hydrophilicity level of polymer matrix and high solvation energy of polar functionalities by Н2О molecules that was concluded from slow moisture elimination process while the temperature grows up to 200–210 оС. Additionally, a dehydration process and changes in a structure of thermally labile filler were also observed at the same temperature interval. At higher temperatures a thermal degradation of polymer poly(AAm-co-2HEMA) matrix is carried out. When a temperature overcomes 400 оС the partially changed filler demonstrates a chemical interaction with degraded organic constituents of the composites and defined catalytic activity as well. Studying sorption activity of the composites shown that introducing NiAl-LDH into hydrophilic polymer matrix provides anion-exchange activity to the composite sorbents and, correspondingly, the ability to eliminate the anionic contaminants from aqueous media while the polymer matrix doesn’t absorb these substances at such conditions. The highest sorption capacity of 11,40 μmol/g against model contaminant – methyl orange dye was determined for composite sorbent with filler content of 70 wt. %. At the same time sorption capacity of NiAl-LDH filler in composite sorbents reduces from 25,7 to 16,6 μmol/g while a filler content grows from 30 to 70 wt.% as a result of filler particles aggregation processes during composites formation stage. To evaluate the ability of the composite sorbents to reuse the experiment of materials recycling was performed. It was stated out the using of anion-exchange technique and aqueous Na2CO3 solution as an efficient and non-hazardous eluent provides 80 % recovering efficiency of the active filler in the composites. It can be concluded the composite sorbents demonstrate a high overall efficiency and are valuable materials for practical application for decontamination of waste water.

Peroxodicarbonate as a Green Oxidizer for the Selective Degradation of Kraft Lignin into Vanillin.

Lignin, the world's largest resource of renewable aromatics, with annually roughly 50 million tons of accruing technical lignin, mainly Kraft lignin, is highly underdeveloped regarding the production of monoaromatics. We demonstrate the oxidative depolymerization of Kraft lignin at 180 °C to produce vanillin 1 in yields up to 6.2 wt % and 92 % referred to the maximum yield gained from the quantification reaction utilizing nitrobenzene. Using peroxodicarbonate (C2 O6 2- ) as "green" oxidizer for the degradation, toxic and/or harmful reagents are prevented. Also, the formed waste can serve as makeup chemical in the pulping process. Na2 C2 O6 is synthesized in an ex-cell electrolysis of aqueous Na2 CO3 at BDD anodes, achieving a yield of Na2 C2 O6 with 41 %. At least, the oxidation and degradation of Kraft lignin is analysis via UV/Vis and NMR spectroscopy.

A Modified Folin-Ciocalteu Assay for the Determination of Total Phenolics Content in Honey

The Folin-Ciocalteu assay is a widely used method for measuring the total phenolic content (TPC) in honey, but it can be affected by the presence of reducing sugars in honey, which can lead to interference and an over-estimation of its TPC. To optimize the Folin-Ciocalteu assay for honey analysis, the effect of pH on the assay was investigated. A number of pH scenarios were tested using different concentrations of Na2CO3 (0.00%, 0.75%, 0.94%, and 7.50%) in order to minimize reducing sugar interference and maximize the reaction of phenolics in the assay. The modified TPC method was then validated in accordance with current International Council on Harmonisation (ICH) guidelines. The findings of this study demonstrate that the traditional Folin-Ciocalteu assay (using 7.50% aqueous Na2CO3 solution, pH 10.8) leads to a significant overestimation of the TPC of honey due to the interference of reducing sugars. However, a pH of 7.9, achieved by using a 0.75% aqueous Na2CO3 solution, provides suitable conditions to account for most of the phenolic compounds without interference from reducing sugars. This finding was further confirmed by testing various sugar solutions and artificial honey which yielded TPC values below the established limit of detection and quantification of the assay. However, a slight increase in pH, even by a moderate deviation (pH 8.9), leads to significant discrepancies in absorbance readings, indicating that pH control is crucial for the accurate analysis of TPC in honey.

Oriented Conversion of a LA/HMF Mixture to GVL and FDCA in a Biphasic Solvent over a Ru Single-Atom/Nanoparticle Dual-Site Catalyst

The industrial use of lignocellulose is limited by the copresence of C5 and C6 carbohydrates in this feedstock and the low selectivity of the corresponding catalytic conversion reaction, which collectively result in suboptimal product yields and necessitate energy-intensive purification/separation processes. Herein, we designed a composite dual-site Ru single-atom (SA)/Ru nanoparticle (NP) catalyst for the hydrogenation of levulinic acid (LA) and the oxidation of 5-hydroxymethyl furfural (HMF) in a biphasic solvent (γ-valerolactone (GVL)-saturated aqueous Na2CO3). Ru-SAs activated LA, while Ru-NPs boosted H2 dissociation to promote the hydrogenation of LA to GVL and ensured the efficient oxidation of HMF to 2,5-furandicarboxylic acid (FDCA). The SA/NP site design increased the oriented conversion efficiency of complex substrates, and the alternate hydrogenation–oxidation process ensured the stability of catalyst activity. The biphasic solvent system not only facilitated the mass transfer process but also allowed the spontaneous and non-energy-intensive separation of the produced GVL and FDCA. The obtained results pave the way for the design of SA/NP dual-site catalysts for the one-pot oriented conversion of complex substrates and the facile separation of products.

Synthesis, Characterization and Antimicrobial Activity of N-Pyridin-3-yl-benzenesulfonamide

This study describes a simple one-pot synthesis of N-pyridin-3-yl-benzenesulfonamide and its antimicrobial activity. The reaction of benzene sulfonyl chloride with 3-aminopyridine in the presence of aqueous Na2CO3 and HCl as a scavenger furnished the sulfonamide in 93.3% yield. The structure of the synthesized compound was established using the spectral data obtained from FTIR, 1HNMR and 13CNMR). All spectrometric spectrum bands and peaks obtained were sulfonamide-related. The antibacterial test carried out against Gram-positive bacterium (Staphylococcus aureus) and Gram-negative bacteria (Salmonella typhi and Eschericha coli) tested upon at concentrations 150, 100, 50 and 25 mg/ml revealed that the synthesized N-pyridin-3yl-benzenesulfonamide possesses great antimicrobial activity.

Efficient production of biodiesel with electric furnace dust impregnated in Na2CO3 solution

Solid catalyst (Na2CO3@EFD) was prepared by wet impregnation of electric furnace dust (EFD) in aqueous Na2CO3 solution. It had high basicity and acidity of 0.34 and 0.16 mmol/g for biodiesel production. High biodiesel yield of 99.8 wt% from soybean oil was obtained under the optimized reaction conditions (by Central Composite Design) of 71 °C in 111.36 min with 5.4 wt% catalyst and methanol/oil molar ratio of 11.8/1. After 11 cycles, biodiesel yield still maintained at 90.8 wt% with catalyst recovery rate >90 wt% by magnetic separation of catalyst EFD powders (containing Fe3O4 with magnetism of 59.1 Am2/kg). Pure Na2CO3 particles presented poorer recyclability with lower biodiesel yield of 89.5 wt% even at the eighth cycle by centrifugal separation. Na2CO3@EFD catalyst had high activity and recyclability because: (i) EFD as support hosted nanoparticles of Na2CO3 (30.3 nm) as main base site for transesterification; (ii) porous EFD support provided acidic sites from metal oxides (e.g., ZnO and Al2O3) for esterification; (iii) EFD adsorbed active components into its micropores to maintain high recyclability; and (iv) EFD magnetism from magnetic Fe3O4 kept high efficient magnetic separation. Total metals in the blended biodiesel met the National Standard of China and heavy metals were lower than typical petrochemical diesel. The study gave a practical use of industrial solid waste for the green production of biodiesel.

Self-Healing Hydrophilic Porous Photothermal Membranes for Durable and Highly Efficient Solar-Driven Interfacial Water Evaporation

Self-Healing Hydrophilic Porous Photothermal Membranes for Durable and Highly Efficient Solar-Driven Interfacial Water Evaporation

A new technique of seawater intrusion control: development of geochemical cutoff wall.

The construction of a subsurface dam and/or physical cutoff barriers is one of the most known techniques used to prevent seawater intrusion during excessive exploitation of freshwater from a coastal aquifer. This method is widely used in many sites around the world (Japan, Brazil, India, Burkina Faso…). In this study, we present an innovative technique for constructing subsurface barriers based on geochemical reactions. A calcite cutoff wall is developed by mixing two aqueous solutions Na2CO3 and CaCl2 under pCO2 equal to 3.16·10-4 bar. The deposition of calcite in the mixing zone induces a high clogging, which greatly reduces the porosity and then the permeability of the aquifer into the injection zone. We use GEODENS code to study the effect of a developed geochemical cutoff wall on saltwater intrusion and to assess their protective effect on preventing seawater intrusion. The GEODENS code can solve these equations by a finite element procedure; it can handle density-dependent flow, transport, and geochemical reactions in porous media. The effect of depth and location of the geochemical cutoff wall is tested and results showed a significant reduction of seawater intrusion penetration length. According to the budget used in many barrier construction projects, we have shown that the developed geochemical cutoff wall presented in this work could produce a lower seawater intrusion penetration length than the traditionally used barriers at a very lower cost.

Hygroscopic Growth and Phase Transitions of Na2CO3 and Mixed Na2CO3/Li2CO3 Particles: Influence of Li2CO3 on Phase Transitions of Na2CO3 and Formation of LiNaCO3.

The hygroscopic behaviors and phase changes of inorganic aerosols have been widely explored, but little is known on the hygroscopicity of soluble carbonates. The hydrated states of solid Na2CO3 particles in an air environment remain largely unclear. In this work, the hygroscopic growth, hydrated form transformations, and influence of internal Li2CO3 on phase transitions of Na2CO3 particles are investigated in linear and pulsed relative humidity (RH) changing modes by the vacuum Fourier transform infrared (FTIR) technique. For pure Na2CO3, aqueous droplets effloresced to a mixture of anhydrous Na2CO3 and Na2CO3·H2O with the initial efflorescence relative humidity (ERH) of 50.8%, probably concerning the formation of Na2CO3·10H2O in the conversion from aqueous to anhydrous Na2CO3. A reverse process is presented during the three-stage deliquescence transition beginning at ∼60.1% RH; i.e., anhydrous Na2CO3 transforms into aqueous Na2CO3 and Na2CO3·10H2O in stage I, Na2CO3·10H2O dissolves to aqueous Na2CO3 in stage II, and Na2CO3·H2O dissolves into aqueous Na2CO3 in stage III. For internally mixed Na2CO3/Li2CO3 particles, a double salt, LiNaCO3, is found in mixed crystalline phases for the first time, leading to the eutonic composition with Na2CO3. The experimental observations point to the excess of LiNaCO3 and complete consumption of Na2CO3 in eutonic composition formation, which results in the absence of Na2CO3 hydrates during phase transitions. The results provide key data for model simulations of hygroscopic properties and phase transitions of Na2CO3 as well as mixed soluble carbonates.

Regeneration of carbonate-intercalated Mg–Al layered double hydroxides (CO3·Mg–Al LDHs) by CO2-induced desorption of anions (X) from X·Mg–Al LDH (X = Cl, SO4, or NO3): A kinetic study

Carbonate-intercalated Mg–Al layered double hydroxides (CO3·Mg–Al LDHs) are examined as a means of sequestering gaseous pollutants, such as HCl, NOx, and SOx, which are bound to afford X·Mg–Al LDH (X = Cl, SO4, or NO3). In view of the fact that the common regeneration method of CO3·Mg–Al LDH (agitation in aqueous Na2CO3) poses a number of problems, we herein develop a new method of regenerating CO3·Mg–Al LDH by treatment of X·Mg–Al LDH with gaseous CO2 under neutral or alkaline conditions. The desorption of X is shown to follow the intraparticle diffusion model, featuring the diffusion of CO32− in between LDH layers as the rate-determining step. Given the importance of LDHs for wastewater treatment and gaseous pollutant removal, the obtained results pave the way to the efficient utilization of these adsorbents and contribute to the development of next-generation decontamination techniques.

Influence of silk fibroin on the preparation of nanofibrous scaffolds for the effective use in osteoregenerative applications

Silk fibroin (SF) based biomaterials have received more attention due to SF's superior biocompatibility, biodegradability, and special properties such as a minimal inflammatory reaction and low immunogenicity especially for the development of bioactive scaffolds in bone regeneration applications. To date, Silk fibroins are blended with a variety of biocompatible polymers and inorganic materials, to enhance their in vitro and in vivo properties. This study includes the detailed protocol of extracting silk fibroin from Bombyx mori silk cocoons followed by the degumming process using aqueous Na2CO3. Hydroxyapatite was synthesized by co-precipitation method using NH4H2PO4 and Ca(NO3)2. 4H2O, later it was blended with extracted silk fibroin and Polyvinyl alcohol (PVA) solution to fabricate desire nanofibers/scaffolds. The viscosity of the blended solution was tuned at an appropriate concentration for the preparation of nanofibrous scaffold by electrospinning and freeze-dried method. The obtained scaffolds were further characterized by FT-IR, XRD, and SEM to confirm the functional groups, phase formation, porosity, and surface morphology. Cell viability was evaluated using MG-63 cell lines and in -vitro bioactivity was further evaluated by immersing in simulated body fluid (SBF) solution. Drug loading and releasing profile of scaffolds were examined using Cephalexin Monohydrate (CEM) in PBS medium. The results inferred that the prepared PVA/HAP/SF based scaffolds showed better osteogenic cell proliferation with prolonged drug release, Hence, this optimized nanofiber may act as an effective material for bone tissue engineering applications.

Ionic liquid‐mediated aqueous two‐phase system to enhance the partitioning of lignin

The aqueous two‐phase system (ATPS) is a promising and efficient alternative platform for the extraction, separation, and purification of biomolecules and bioproducts. In this work, four different imidazolium‐based ionic liquids with Cl− as anions and with different cations with aqueous Na2CO3 (inorganic salt) acting as the salting out agent were used to form the ATPS for the partitioning of lignin. The effects of the cation core and the length of the alkyl side chain of the ionic liquids on the formation of the ATPS were investigated using the phase diagram determined by the cloud point titration method, and the corresponding tie lines were measured and reported. It was found that the hydrophobicity of the ionic liquids plays a major role in the phase formation. The effects of the concentrations of IL, Na2CO3, and lignin as well as temperature on the partition coefficient and the extraction efficiency of lignin in the IL‐mediated ATPS were investigated, and the optimum conditions were established. It was found that the high extraction efficiency (∼99 %) and partition coefficient (∼47) of lignin in the IL‐mediated ATPS were achieved with the following parameters: Na2CO3 40 % (w/w); [HMIM]Cl 0.4 mol/L; lignin 0.006 mol/L; and at a temperature of 328 K. The thermodynamic study on lignin partitioning in the IL‐mediated ATPS was also investigated by varying the temperature range from 298–328 K, from which it was observed that the partitioning of lignin in the ATPS increases with an increase in temperature. This suggests that the process is endothermic in nature.

Effect of sodium content on the interaction between Ni and support and catalytic performance for syngas methanation over Ni/Zr–Yb–O catalysts

In this paper, Ni/Zr–Yb–O catalysts with different sodium contents are prepared by a co-precipitation method, using aqueous Na2CO3 solution as a precipitant, and the effect of sodium on the catalyst structure and catalytic performance for syngas methanation is extensively investigated using five Ni/Zr–Yb–O catalysts, containing 0, 0.5, 1.5, 4.5 and 13.5 wt% Na+, those are denoted as Cat-1, Cat-2, Cat-3, Cat-4 and Cat-5 respectively. It is found that the interaction between Ni and support determines the catalytic performance of Ni/Zr–Yb–O and the residual sodium content negatively affects the interaction between Ni and support. Cat-1 exhibits an excellent catalytic performance. During a long run time of 380 h, no deactivation is observed and both CO conversion and CH4 selectivity maintain a level above 90%. However, Cat-3 and Cat-5 suffer rapid deactivation under the same reaction condition. The characterization results indicate the strong interaction between Ni and support enables Cat-1 to possess well dispersed Ni species, resistance to sintering and carbon deposition and thus the excellent catalytic performance. However, the presence of sodium ions over Ni/Zr–Yb–O degrades the interaction between Ni and support and the catalytic performance, especially for the stability. The relative weak interaction between Ni and support results in severe sintering of both ZrO2 and Ni under the reaction condition, carbon deposition and the poor catalytic performance.

Synthesis of new 2-{2,3-dihydro-1,4-benzodioxin-6-yl[(4-methylphenyl) sulfonyl]amino}-N-(un/substituted-phenyl)acetamides as α-glucosidase and acetylcholinesterase inhibitors and their in silico study

The aim of the present research work was to investigate the enzyme inhibitory potential of some new sulfonamides having benzodioxane and acetamide moieties. The synthesis was started by the reaction of N-2,3-dihydrobenzo[1,4]-dioxin-6-amine (1) with 4-methylbenzenesulfonyl chloride (2) in the presence of 10% aqueous Na2CO3 to yield N-(2,3-dihydrobenzo[1,4]-dioxin-6-yl)-4-methylbenzenesulfonamide (3), which was then reacted with 2-bromo-N-(un/substituted-phenyl)acetamides (6a-l) in DMF and lithium hydride as a base to afford various 2-{2,3-dihydro-1,4-benzodioxin-6-yl[(4-methylphenyl)sulfonyl] amino}-N-(un/substituted-phenyl)acetamides (7a-l). All the synthesized compounds were characterized by their IR and 1 H-NMR spectral data along with CHN analysis data. The enzyme inhibitory activities of these compounds were tested against -glucosidase and acetylcholinesterase (AChE). Most of the compounds exhibited substantial inhibitory activity against yeast -glucosidase and weak against AChE. The in silico molecular docking results were also consistent with in vitro enzyme inhibition data.

Production of CuO nanoparticles using a simple precipitation method in a rotating packed bed with blade packings

CuO nanoparticles were produced using a simple precipitation method in a rotating packed bed with blade packings in continuous mode. The reactant and precipitant were CuSO4 and Na2CO3, respectively. The effects of the rotational speed, the flow rates of aqueous CuSO4 and Na2CO3, and the concentrations of CuSO4 and Na2CO3 on the size of the produced CuO nanoparticles were studied. The results thus obtained indicate that a lower rotational speed and smaller flow rates of aqueous CuSO4 and Na2CO3 yielded smaller CuO nanoparticles. However, increasing concentrations of CuSO4 and Na2CO reduced the size of the produced CuO nanoparticles. The smallest CuO nanoparticles, which had an average size of 54 nm, were produced at a rotational speed of 600 rpm, flow rates of aqueous CuSO4 and Na2CO3 of 0.3 L/min, a CuSO4 concentration of 0.3 mol/L, and an Na2CO3 concentration of 0.3 mol/L. The catalytic activity of the smallest CuO nanoparticles was evaluated by using them to degrade methylene blue with H2O2. CuO nanoparticles effectively activated H2O2 and so degraded methylene blue with an efficiency of 62% in 90 min.

The influence on the structural and redox property of CuO by using different precursors and precipitants for catalytic soot combustion

To gain fundamental understanding on the catalytic property of individual CuO for soot combustion, a series of CuO samples have been prepared with a simple precipitation method by using different Cu precursors and precipitants. Pure monoclinic CuO crystalline phase has been detected by XRD and Raman for all the samples. However, by changing the precursors and precipitants, the morphology and texture property of the CuO samples can be influenced. Furthermore, the redox property of the CuO catalysts can also be altered. Soot-TPR results have testified that four types of active sites with varied activity are present on the surface of all the samples, but only the two types of active sites that can be reduced by soot particles below 500 °C are believed to contribute effectively to soot combustion. It has been discovered that the surface oxygen mobility and abundance are the crucial factors to determine the soot combustion activity of CuO catalysts. Because of the optimal balance of these two factors, CuO-Cu(NO3)2-Na2CO3, a CuO catalyst prepared by the combination of Cu(NO3)2 precursor and aqueous Na2CO3 precipitant, displays the highest soot combustion activity among all the catalysts.

Use of counter-current chromatography as a selective extractor for the diterpenequinone 7α-hydroxyroyleanone from Tetradenia riparia

A solvent system was developed for selective isolation by high-speed counter-current chromatography (HSCCC) of the benzoquinone 7α-hydroxyroileanone, 1, a bioactive diterpene from a dichloromethane extract of Tetradenia riparia leaves. Several solvent systems were initially studied, including hexane-ethyl acetate-methanol-water in several ratios, hexane-acetone-methanol-water, hexane-ethanol-water and hexane-acetonitrile-methanol, which gave recovery rates for the target compound between 13.4 and 35.9%. The new solvent system hexane-5% aqueous Na2CO3 (1:1) was developed based on the chemical ionization reaction of the benzoquinone hydroxyl group in the basic pH of the carbonate solution, prompted by the extraction procedure used for the extraction of lapachol (a natural naphtoquinone) from a Tabebuia species wood. By using the HSCCC chromatograph as a liquid–liquid extractor with the above mentioned solvent system the recovery rate of 1 increased to 81.8%, affording the quinone with 97% purity.

CO2 capture by aqueous Na2CO3 integrated with high-quality CaCO3 formation and pure CO2 release at room conditions

The absorption of carbon dioxide from anthropogenic emissions and its utilization as a building block for the synthesis of useful chemicals is gaining increasing interest in recent years as an alternative to the conventional CO2 capture and storage (CCS) technologies. The conversion of carbon dioxide into valuable commodities has the advantage of avoiding the energy penalties of absorbent regeneration, CO2 compression and its disposal underground.In this paper we report a novel semi-continuous technique of CO2 capture from a gas mixture by dilute (0.83moldm−3) aqueous solutions of Na2CO3 with a sufficiently high absorption efficiency (about 80%) combined with the nearly quantitative production of high quality CaCO3 and CO2 minimizing the energy requirements since the entire process occurred at room conditions. The highly pure CaCO3 and CO2 recovered by the process are valuable products that have the potential of reducing the costs of the CO2 capture process. The 13C NMR spectroscopy is employed to identify and quantify the species in solution.

Synthesis of N-Substituted (2,3-Dihydro-1,4-Benzodioxin-6-YL)Benzenesulfonamide Derivatives as Potent Antibacterial Agents and Moderate Enzyme Inhibitors

The present research work involved the reaction of 2,3-dihydro-1,4-benzodioxin-6-amine (1) and benzenesulfonyl chloride (2) under dynamic pH control at 10 using aqueous Na2CO3. This reaction yielded 2,3-dihydro-1,4-benzodioxin-6-yl)benzenesulfonamide (3), which was further substituted at N-position with various alkyl/aryl halides (4a – 4m) in N,N-dimethylformamide and catalytic amount of lithium hydride to obtain N-substituted (2,3-dihydro-1,4-benzodioxin-6-yl)benzenesulfonamides (5a – 5m). The projected structures of the synthesized derivatives were confirmed using various spectral techniques (IR, 1H NMR and EIMS). The synthesized derivatives were screened for antibacterial potential and inhibitory activity against lipoxygenase enzyme.