Sodium Carbonate Medium Research Articles

Two Approaches for CAL-B-Catalyzed Enantioselective Deacylation of a Set of α-Phenyl Ethyl Esters: Organic Solvent with Sodium Carbonate and Micro-aqueous Medium

Herein, we report an efficient enantioselective cleavage of the acyl- moiety of a set of α- phenyl ethyl esters with different chain-lengths catalyzed by lipase B from Candida antarctica (CAL-B) by comparing two reactional approaches: anhydrous media with sodium carbonates and micro-aqueous medium. The deacylation is performed in organic solvent, in the presence of Na2CO3 in the first case, and by addition of a drop of phosphate buffer solution pH 7 in the second. The results show the high efficiency of the deacylation in the presence of the sodium carbonate for the enzymatic resolution of all the esters and that in term of reactivity (31% ≤ conv ≤ 50%) and selectivity (E > 200). While, during the hydrolysis in micro-aqueous media, the conversion is strongly affected by the length of the acyl-chain side, the conversion decreases from conv = 50% with the 1-phenylethyl acetate 1a to conv = 19% with 1-phenyethyl dodecanoate 6a, and this, even if the selectivity remains high (E > 89). In both conditions, the lipase CAL-B shows a high enantioselectivities in favor of (R)-1-phenyl ethanol enantiomer (conv > 45%, E > 200) but the reactivity is modulated by the form and the size of the acyl-chain side.Graphic Abstract

Production of high quality ammonium uranyl carbonate from “uranyl nitrate + carbonate” precursor solution

The purpose of this study is to investigate production of high quality ammonium uranyl carbonate (AUC) from “uranyl nitrate + ammonium bicarbonate”, or “uranyl nitrate + sodium carbonate” precursor solutions, by controlled injection of ammonium carbonate solution which could be applicable in material testing reactor (MTR) fuel production plant for recycling of rejected uranium oxide powder. The experimental observations revealed: at pHs higher than 6, precipitation proceeds with formation of no intermediate, thus ensuing a better morphology and size distribution of the AUC products. The results of scanning electron microscopy, X-ray diffraction, particle size analysis, and uranium content analysis showed that precipitation of AUC in the sodium carbonate medium was slow and incomplete (with a yield around 40%); and quality of the precipitate and morphology of its particles could not meet the required criteria. In contrast, ammonium bicarbonate medium resulted in the AUC crystals with suitable morphology and appreciable particle size distribution. In the latter case, precipitation was fairly well modelled by simple “diffusion-reaction” model. Application of the supersaturated ammonium bicarbonate solution for precipitation resulted in the following advantages over the sub-saturated solution: 1) higher yield of uranium precipitation, 2) smaller size of AUC particles (dmean≈86 μm compared to 112 μm for sub-saturated), 3) lower degree of crystals agglomeration, 4) lesser formation of cracks on the surface of U3O8 particles, which are prepared as the products from AUC. The final U3O8 powder, after sintering and milling, appears to be smooth and rounded, and was qualified for MTR fuel plate fabrication.

An Experimental Design Approach for Optimization of Spectrophotometric Estimation of Mirabegron in Bulk and Pharmaceutical Formulations

Three simple, low-cost, sensitive and diversely applicable UV-Vis spectrophotometric methods have been developed for the estimation of drug Mirabegron. Method A is based on the reaction of Mirabegron with ninhydrin in the presence of sodium molybdate at pH 5.5. Method B is based on the reaction of the drug with 1,2-napthaquinone-4-sulphonate and cetyltrimethyl ammonium bromide in an alkaline medium. Method C is based on a redox reaction of the drug with Folin–Ciocalteu reagent in sodium carbonate medium. Beer’s law was obeyed in the concentration ranges of 2.5–22.5, 5–35, and 5–70 μg/mL for methods A, B, and C. The proposed methods can be applied to drug formulation and recommended for the routine analysis in quality control laboratories.

The process chemistry and mineralogy of brannerite leaching

Brannerite (UTi2O6) is the most important uranium mineral after uraninite and coffinite, and the most common refractory uranium mineral. As the more easily leachable uranium ores are becoming exhausted, it is necessary to process the complex and refractory ores in order to meet the growing demand for uranium as an energy source. This typically requires either more intense leaching conditions or a better-designed process based on sound understanding of feed mineralogy and reaction chemistry. The present study was carried out to provide information that will enable the development of a more effective processing strategy for the extraction of uranium from ores containing brannerite. The leaching behaviour of brannerite in sulphate media under moderate temperature conditions was investigated and compared with its relative leachability in alternative acid and alkaline systems. The feed and the leached residues were characterized by XRD and SEM-EDX techniques. Brannerite dissolutions of up to 95% after 5 hours of leaching in ferric sulphate media, up to 89% in ferric chloride media under similar conditions, and up to 82% in 24 hours in sodium carbonate media were obtained. Since alkaline leaching was considered promising for acid-consuming ores, leaching was repeated with a high-carbonate brannerite-bearing ore, with comparable extractions. Mineralogical characterization showed that altered and amorphous regions are a regular feature of brannerite, and that pitting is typically observed on the surface of the leached grains. The leaching results, coupled with mineralogical data, showed that the uranium and titanium in brannerite generally dissolve congruently, with faster dissolution of the altered and amorphous regions in the brannerite grains than of the crystalline regions. We conclude that the extent of brannerite alteration is a key factor in process selection, along with the grade, liberation size, and gangue mineralogy.

Spectrophotometric determination of ethionamide in pharmaceuticals using Folin–Ciocalteu reagent and iron(III)-ferricyanide as chromogenic agents

Two simple and sensitive spectrophotometric methods are described for the determination of ethionamide (ETM) in pure drug and tablets. The first method is based on the reduction of Folin–Ciocalteu (F–C) reagent by ETM in sodium carbonate medium to form a blue coloured complex, which was measured at 760nm (Molybdenum–tungsten blue method). In the second method (Prussian blue method), iron(III) was reduced to iron(II) by ETM in HCl medium, in which iron(II) was complexed with ferricyanide, and the resulting Prussian blue was also measured at 760nm. The absorbance measured in each case was related to the ETM concentration. The experimental conditions were carefully studied and optimised. Beer's law was obeyed in concentration ranges of 1–40μg/ml and 0.2–4.0μg/ml with the Molybdenum-tungsten blue method and the Prussian blue method, respectively, with corresponding molar absorptivity values of 5.72×103 and 3.18×104l/(mol·cm). The limits of detection (LOD) and quantification (LOQ) were 0.09 and 0.27μg/ml for the Molybdenum-tungsten blue method and 0.01 and 0.04μg/ml for the Prussian blue method. Within-day and between-day relative standard deviations (%RSD) at three different concentration levels were <3%, and the respective relative errors (%RE) were ≤2%, implying good accuracy and precision of the methods. The proposed methods were successfully applied to the determination of ETM in bulk powder and tablets, and the results demonstrated that the methods were as accurate and precise as the official method.

Novel preparation of a porous composite insulating scaffold from forsterite and sodium carbonate media

Abstract Porous composite insulating scaffolds were prepared from mixtures of forsterite, salt (Na2CO3), and phenolic resin by sintering at 900 to 1 100 °C for 10 h, and the sintering behaviour and mechanical properties were examined. The results show that the changes in temperature did not significantly affect the phases present in the samples. However, changing the Na2CO3 content of a sample will change its phase composition. When the Na2CO3 content was 40 wt.% and sintering undertaken at 1 000 °C, the apparent porosity of the sample was 57 %, and its strength was 3.1 MPa. The large number of pores in the samples had diameters of approximately one micron, while the mesopores had diameters concentrated over the interval of 3 to 5 nm.

Ninhydrin-based spectrophotometric assays of trace cyanide

Abstract The extreme toxicity of cyanide, its wide industrial application as well as its continued illegal use generate research interest in different fields of science, imposing multidisciplinary approach to study cyanide poisoning. We show here that the reaction between cyanide and ninhydrin can be performed at ambient conditions; however, the ninhydrin reagent has to be freshly prepared in oxygen free solvent. Besides, we show that the reading of the absorbance at 485 nm might be more suitable and reliable than that at 590 nm, where the pH-dependent blue colored cyanide-ninhydrin adduct is less stable. Ninhydrin-based color reagent can be used to quantify the cyanide released from plant seeds. In sodium carbonate medium, the proposed assay is fast, cheap and environmentally friendly

Electrochemical copolymerisation of luminol with aniline: A new route for the preparation of self-doped polyanilines

Electrochemical copolymerisation of luminol and aniline from acidic aqueous medium onto gold electrodes has been investigated. Cyclic voltammetry in combination with electrochemical quartz crystal microbalance (EQCM) have been used to study both the in situ growth and redox switching process. In monomer free solution, the deposited polymers are stable and electrochemically active but distinct behaviour is shown by poly(luminol-aniline) films obtained from solutions with different monomers concentration ratio. In acidic medium, the current–voltage profiles range from a polyluminol (one pair of redox couple) to a polyaniline like redox conversion (three redox couples) as the aniline concentration increases. Unlike polyaniline, all prepared copolymers display well expressed electroactivity in sodium carbonate medium (pH 8), which also extends with the aniline content. The self-doping role assured by luminol moiety in the copolymer is also retrieved from the simultaneously recorded EQCM data.

Thialkalivibrio halophilus sp. nov., a novel obligately chemolithoautotrophic, facultatively alkaliphilic, and extremely salt-tolerant, sulfur-oxidizing bacterium from a hypersaline alkaline lake.

A new chemolithoautotrophic, facultatively alkaliphilic, extremely salt-tolerant, sulfur-oxidizing bacterium was isolated from an alkaline hypersaline lake in the Altai Steppe (Siberia, Russia). According to 16S rDNA analysis and DNA-DNA hybridization, strain HL 17T was identified as a new species of the genus Thialkalivibrio belonging to the gamma subdivision of the Proteobacteria for which the name Thialkalivibrio halophilus is proposed. Strain HL 17T is an extremely salt-tolerant bacterium growing at sodium concentrations between 0.2 and 5 M, with an optimum of 2 M Na+. It grew at high concentrations of NaCl and of Na2CO3/NaHCO3 (soda). Strain HL 17T is a facultative alkaliphile growing at pH range 7.5-9.8, with a broad optimum between pH 8.0 and 9.0. It used reduced inorganic sulfur compounds (thiosulfate, sulfide, polysulfide, elemental sulfur, and tetrathionate) as energy sources and electron donors. In continuous culture under energy limitation, thiosulfate was stoichiometrically oxidized to sulfate. In sodium carbonate medium under alkaline conditions, the maximum growth rate was similar, while the biomass yield was lower as compared with the NaCl-grown culture. The maximum sulfur-oxidizing capacity measured in washed cells was higher in the soda buffer independent of the growth conditions. The compatible solute content of the biomass was higher in the sodium chloride-grown culture than in the sodium carbonate/bicarbonate-grown culture. The data suggest that the osmotic pressure differences between soda and NaCl solutions might be responsible for the difference observed in compatible solutes production. This may have important implications in overall energetic metabolism of high salt adaptation.

Interaction of Glycosphingolipids with Signal Transducers and Membrane Proteins in Glycosphingolipid-Enriched Microdomains

Publisher Summary This chapter focuses on the interaction of glycosphingolipids with signal transducers and membrane proteins in glycosphingolipid-enriched microdomains (GEMs), and describes the isolation, chemical composition, and functional characterization of GEMs or glycosynapses from a few types of cells. The general procedure for preparation of GEMs is discussed. Two conditions are used for the lysis and homogenization of cells: (i) in a medium containing 1% Triton X-100 and (ii) in hypertonic sodium carbonate medium followed by sucrose density gradient ultracentrifugation to separate low-density buoyant fraction from high-density soluble fraction. The chapter also discusses the interaction of GalNAcDSLc 4 ganglioside with cSrc and RhoA in GEM from the renal cell carcinoma cell line TOS1; the interaction of GalNAcDSLc 4 and signal transducer molecules from the GEM Fraction of TOS1 cells; the coordinated interaction of GM3 with cSrc and Csk the physiological inhibitor of cSrc,in Neuro2a cells; and the interaction of GM3 ganglioside with tetraspanin CD9/Integrin α3 complex in ldlD/CD9 cells.

Desulfonatronovibrio hydrogenovorans gen. nov., sp. nov., an Alkaliphilic, Sulfate-Reducing Bacterium

A new alkaliphilic, sulfate-reducing bacterium, strain Z-7935T (T = type strain), was isolated from a soda-depositing lake, Lake Magadi in Kenya. This organism is a motile vibrio which utilizes only hydrogen and formate as electron donors and sulfate, sulfite, and thiosulfate, but not sulfur, as electron acceptors. Thiosulfate is dismutated. Strain Z-7935T is an obligately sodium-dependent alkaliphile which grows in sodium carbonate medium and does not grow at pH 7; the maximum pH for growth is more than pH 10, and the optimum pH is 9.5 to 9.7. The optimum NaCl concentration for growth is 3% (wt/vol). The optimum temperature for growth is 37 degrees C. The G + C content of the DNA is 48.6 mol%. 16S ribosomal DNA sequence analysis revealed that strain Z-7935T represents a new lineage with genus status in the delta subclass of the Proteobacteria. The name Desulfonatronovibrio hydrogenovorans gen. nov., sp. nov. is proposed for this organism; the type strain of D. hydrogenovorans is strain Z-7935 (= DSM 9292).

Studies on sorption of plutonium on inorganic ion exchangers from sodium carbonate medium

Sorption of Pu(IV) from sodium carbonate medium has been investigated by using three inorganic ion exchangers, viz. alumina, silica gel and hydrous titanium oxide (HTO). Distribution ratios (D) of Pu(IV) for its sorption on these ion exchangers have been determined. The values are 700, 103 and 104 for alumina, silica gel and hydrous titanium oxide, respectively, from 0.1M sodium carbonate medium. The high distribution ratios indicate their suitability for the removal of Pu(IV) from sodium carbonate waste streams. Pu(IV) breakthrough capacities have been determined with 5 ml bed at a flow rate of 30 ml per hour. The 10% Pu(IV) breakthough capacities for alumina and silica gel are 3 g l−1 and 14 g l−1, respectively. The capacity of HTO is 60 g of Pu(IV) per liter of exchanger at 4% Pu(IV) breakthrough.

Studies on gold elution and electrowinning using sodium carbonate media

Laboratory-scale experiments on gold elution and electrolysis in sodium carbonate media were performed. The effect of solution composition, flow rate, and acid washing on the elution of gold from loaded carbons was studied. Both laboratory and plant loaded carbons were evaluated for their elution behaviour. It was found that the percent of gold eluted was greatly influenced by the temperature, acid concentration, and residence time of the acid washing step.The concentration of sodium carbonate affects the elution of the gold. In some cases, a mixture of sodium carbonate and sodium hydroxide was more effective than sodium carbonate alone.The electrolysis behaviour of some plant was studied to ascertain whether problems with anode corrosion, scale formation and poor gold deposition kinetics were associated with the medium properties or the process practice. It was found that the solution composition had to be compatible with both elution and electrowinning to avoid disruption of the gold mill circuit.

The conversion of lead sulphate to lead carbonate in sodium carbonate media

The reaction of sized PbSo 4 powders with Na 2CO 3 media has been investigated over a broad range of experimental conditions. The reaction obeys the shrinking core model incorporating diffusion through the product layer formed on the particles. The rate increases as the first power of the Na 2CO 3 concentration and decreases with increasing concentrations of the Na 2SO 4 reaction product. The rate is independent of NaNO 3 additions, but decreases with increasing concentrations of NaCl or KCl. At a given Na 2CO 3 concentration, the rate decreases as the pH decreases because of the conversion of CO 3 2− ions to HCO 3 −. The rate decreases significantly when the pH raised from 11.5 to 12.0, and this decrease is attributed to changes in the reaction products/product morphologies. At pH values > 12, the PbSO 4 dissolves in the solution. The PbSO 4 conversion rate increases with increasing temperature, and the apparent activation energy is 15.8 kJ/mol. Hydrocerussite, Pb 3(CO 3) 2(OH) 2, is formed under mild reaction conditions, but the formation of NaPb 2(CO 3) 2(OH) is favoured by long retention times, high Na 2CO 3 or NaCl concentrations and elevated temperatures. The experimental results support a mechanism based on rate control by the diffusion of carbonate ions through the solution trapped in the pores of the constantly thickening product layer formed on the agglomerated PbSO 4 particles.

The behaviour of plutonium in aqueous basic media

Behaviour of Pu(IV) and Pu(VI) in basic media has been investigated by studying their stabilities and quantitative determination by spectrophotometry. Beer's law was found to be obeyed in the range of 1·10−3 to 5·10−3 M Pu(IV) at 485 nm peak with a molar absorption coefficient of 95M−1· cm−1 in sodium carbonate medium. In case of Pu(VI), in the same medium Beer's law was obeyed in the concentration range of 2·10−3 to 1·10−2M at 550 nm with a molar absorption coefficient of 50M−1·cm−1. Distribution ratios of Pu(IV) and Pu(VI) for their sorption on Al2O3 and Amberlyst A-26 (MP) resin from bicarbonate and carbonate media have been determined. High distribution ratios obtained indicate the feasibility of decreasing the plutonium content of basic carbonate streams in reprocessing. 10% breakthrough capacities for Pu(IV) and Pu(VI) with these exchangers during column operations have also been determined.

Spectrophotometric Determination of Bismuth(III) and Indium(III) with 2,4,6-Tris(2-hydroxy-4-sulfo-1-naphthylazo)-1,3,5-triazine Trisodium Salt (THT)

Abstract Reaction behavior of bismuth(III) and indium(III) with 2,4,6-tris(2-hydroxy-4-sulfo-1-naphthylazo)-1,3,5-triazine trisodium salt (THT) is established under various conditions. Bismuth(III) forms a 2 : 3 dark red complex (absorption maximum at 530 nm) with the reagent at pH 4–6.5. Indium(III) reacts with THT to form a 1 : 2 dark red complex at pH 3–4.7 (λmax 530 nm) and a 1 : 3 purple blue complex at pH ca. 10.5 (λmax 620 nm). The molar absorptivities for the color reactions are 5.5×104 for bismuth(III), 8.4×104 for indium(III) at pH 3.5 and 7.9×104 L·mol−1·cm−1 for indium(III) at pH ca. 10.5 (in sodium carbonate medium). Other physicochemical characteristics of the complexes are established. A number of foreign ions are tested for their interference and the use of masking agents wherever necessary is tabulated.

Potentiometric determination of 8-chlorotheophylline

Two methods are described for the potentiometric determination of 8-chlorotheophylline in aqueous solution. Both methods are based on the reaction of 8-chlorotheophylline with silver ions. In the first, the nitric acid produced in the reaction is titrated with sodium hydroxide. In the second, the 8-chlorotheophylline is titrated directly with silver nitrate in sodium carbonate medium. Both methods give reasonably accurate and reproducible results, and are suitable for the assay of 8-chlorotheophylline in pharmaceutical preparations.

Oxidation of residuum in aqueous sodium carbonate medium and use of oxidized product to improve adhesion properties of asphalt

Oxidation of residuum in aqueous sodium carbonate medium and use of oxidized product to improve adhesion properties of asphalt

The determination of organic substances by the oxidation with permanganate: XVIII. The oxidation of malonic acid

The oxidation of malonic acid with permanganate was studied under various acidity conditions. Analytical procedures, based on oxidation with excess reagent in a sodium carbonate medium and titration of the oxalate or manganese dioxide formed or of unconsumed permanganate, are proposed. On the basis of successive oxidation in sodium carbonate and sulfuric acid media, a titration determination, involving complete oxidation of malonic acid to carbon dioxide and water, was developed.