Amount Of NaBr Research Articles

Effect of acidic conditions on electrochemical desulfurization of clean coal

ABSTRACT In this study, the electrochemical indirect oxidation desulfurization of organic sulfur in coal was carried out using a diaphragmless electrolytic cell. The desulfurization effect of NaBr, HCl, HNO3, and H2SO4 in the electrolysis system with different acid concentrations of pH = 1–6 was investigated, and the reaction mechanism and desulfurization were analyzed. After the impact on coal quality. In the experiment, the clean coal with high organic sulfur content after washing from Shanxi’an Yi Coal in China was used as the raw material. After grinding, it was suspended in three different electrolyte systems of NaBr-HCl, NaBr-HNO3, and NaBr-H2SO4 to control different pH values. Desulfurization of coal particles suspended in the electrolyte is carried out by generating active oxides through electrode reaction, and the influence of desulfurization conditions on coal quality is analyzed using the whole industry analysis index and the test results of TGA, FTIR and EDS. The results show that a certain amount of NaBr and acid have different electrochemical desulfurization effects in different environments with pH = 1–6. The same acid has different desulfurization effects at different pH and different acids at the same pH, which has different effects on coal quality. There are also significant differences. The relative content of oxygen in coal samples increased after desulfurization, resulting in a decrease in the relative content of carbon, lowering the calorific value of the coal and improving the combustion performance; in the environment of HCl pH = 6, the electrolytic desulfurization reaction will cause Cl substitution reaction, H2SO4 under pH = 6 environment, the oxygen content increases significantly, causing serious deterioration of coal quality. Compared with HCl and H2SO4, HNO3 pH = 6 environment is better. It can effectively remove organic sulfur from clean coal and maintain the basic structure of coal without change, as ash content is reduced.

Effect of coexisting salt on TEMPO-mediated oxidation of wood cellulose for preparation of nanocellulose

The influence of coexisting salt in 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-mediated oxidation of wood cellulose in water at pH 10 for 100 min was investigated, in which Na2SO4 was partly used in place of NaBr in the conventional TEMPO/NaBr/NaClO oxidation system. The amount of NaBr could be reduced from 1 to 0.2 mmol/g-wood cellulose by adding 0.4 mmol/g Na2SO4. This introduced a carboxylate content of ~1.2 mmol/g, which is sufficient to prepare TEMPO-oxidized cellulose nanofibrils (TOCNs) by mechanical disintegration of the oxidized cellulose in water. When no NaBr was used and Na2SO4, Na2SO3, NaCl or CH3COONa was instead used as a coexisting salt in TEMPO/NaClO oxidation, the oxidized celluloses had carboxylate contents of 0.6–0.8 mmol/g, which are insufficient to prepare TOCNs with nanofibrillation yields >55%. The viscosity-average degrees of polymerization of the resulting TEMPO-oxidized celluloses were in the range 420–450, indicating that depolymerization of cellulose is not governed by the carboxylate content of the TEMPO-oxidized cellulose but rather by the oxidation time.

Preparation of water‐soluble oxidized starch with high carbonyl content by sodium hypochlorite

Water‐soluble oxidized starch with high carbonyl content (DOCO = 0.40) was prepared using a one‐step method with sodium hypochlorite (NaClO) as the primary oxidant and under the mediation of sodium bromide (NaBr) and hydroxylamine hydrochloride (NH2OH · HCl). The influences of pH, initial starch concentration, and the amount of NaBr and NH2OH · HCl on the carbonyl and carboxyl content were discussed. The molar ratio of carbonyl to carboxyl groups can be adjusted from 0.8 to 2.2 by controlling the dropping speed of NaClO. The formation of carbonyl and carboxyl groups on the oxidized starch was confirmed by Fourier‐transform infrared (FT‐IR) and 13C NMR spectroscopy. The molecular weight of the oxidized starch determined by SEC revealed modest degradation. Besides, a good solubility of the oxidized starch in cold water was also proved based on the study of its solubility and swelling properties.

A Simple, non‐Destructive Method for Bromide Analysis in Plasma for Field Body Composition Studies

ObjectiveExpansion of extracellular water (ECW) space serves as a measure of muscle loss, cachexia or inflammation. It is used to monitor frailty, depletion of muscle mass, and the efficacy of nutritional interventions. ECW is measured by bromide dilution, where a known amount of NaBr is administered and a plasma (or urine) sample is analyzed, after equilibrium, by instrumental neutron activation analysis (INAA) or high‐performance liquid chromatography (HPLC). The objective of this work is to develop an alternative, automated method of analysis that does not require the complexity of INAA or HPLC.MethodWe tested a non‐destructive energy dispersive X‐ray fluorescent (XRF) device which uses a Cd‐109 radioactive source, a miniature (25 mm2), electronically cooled, high resolution (<150 eV) silicon detector and a microprocessor‐controlled sample‐positioning system to obtain X‐ray spectra from plasma samples. The method requires no sample preparation and preserves 100% of each specimen.ResultsSensitivity: 0.1ug/cc, reproducibility for Br in plasma or urine <0.8%, accuracy <1.0%. Validated against INAA (R2=0.994).ConclusionThe method can be used in the field for repeated measurements. The lack of sample preparation eliminates the opportunity for bromide loss due to filtering. Being non‐destructive, XRF allows for full preservation of the specimen. Support: USDA contr. 51000–071

Facile and controllable incorporation of gold nanoparticles within one-dimensional self-assemblies of hyperbranched polymers

Using a mono-pyrene terminated hyperbranched polyglycidol (mPTHP) as a building block, one-dimensional (1D) mPTHP and mPTHP/gold nanoparticle (Au NP) nanostructures are fabricated in the presence of HAuCl4. By simply mixing mPTHP and different concentrations of aqueous HAuCl4 solution at room temperature, mPTHP nanofibers and nanotubes are obtained through Au(III) ion induced self-assembly processes. Upon elevating the reaction temperature from room temperature to 60 °C, Au NPs are in situ generated within 1D mPTHP assemblies via an analogous “polyol process”, forming mPTHP/Au NP hybrid nanofibers and nanotubes. Careful control of the HAuCl4 concentration enables in situ generated Au NPs to be either distributed along the center-line of nanofibers or symmetrically aligned into a double-line along the nanofibers and the inner surface of nanotubes. Further investigation reveals that the involvement of a small amount of NaBr in the reaction system of mPTHP and different amounts of HAuCl4 results in the formation of pseudo-nanotubes decorated with double-lined Au NP chains along their inner surfaces. Moreover, the size of Au NPs can be effectively tuned in terms of HAuCl4 concentration. All 1D mPTHP and mPTHP/Au NP nanostructures described in our current work are achieved through one-pot aqueous reactions in the absence of any additional reducing agents, surfactants and organic solvents, so that they are facile, green and low-cost strategies. To the best of our knowledge, this is the first example to synthesize 1D hyperbranched polymer/metal NP hybrid nanostructures with controllable spatial distribution of NPs using such a facile and green protocol.

Influence of sodium bromide on the thermal decomposition of tetraphenylphosphonium montmorillonite

Tetraphenylphosphonium montmorillonite (TPP-MMT) was prepared from an aqueous solution of tetraphenylphosphonium bromide and a bentonite consisting primarily of sodium rich montmorillonite (Na-MMT) together with minor amounts of cristobalite, quartz and nontronite. The original bentonite, the TPP-MMT and mixtures of TPP-MMT with various amounts of NaBr were investigated by in-situ high-temperature X-ray diffraction and thermogravimetric analysis. The decomposition of TPP-MMT was strongly dependent on the presence of NaBr. NaBr took part in a retro-reaction to Na-MMT + TPP-Br, of which the latter decomposed into gaseous products. The decomposition temperature of pure TPP-MMT was about 100 °C higher than mixtures of TPP-MMT with NaBr. The TPP-ions in pure TPP-MMT decomposed continuously within the MMT interlayer space, so that there was probably nothing left but H +. Since NaBr is a by-product of the TPP-MMT synthesis from Na-MMT and since halogen ions strongly influence fire retardant properties of polymer-based composites, this reaction is a critical aspect in the evaluation of such materials. Cristobalite and quartz were inert during the reactions observed up to temperatures of 1000 °C.

Synthesis of silver nanocubes and nanorods through sodium-bromide-assisted polyol route

Silver nanocubes and nanorods were prepared with the assistance of sodium bromide (NaBr) through a developed polyol route. The addition of different amounts of NaBr could tune morphologies of silver nanostructures. Transmission electron microscopy, high-resolution transmission electron microscopy, selected areas electron diffraction and X-ray diffraction were employed to characterise silver nanocubes and nanorods. The growth mechanisms of silver nanocubes and nanorods were discussed by taking account of the formation of single crystal and multiply twinned seeds, respectively.

ChemInform Abstract: A Novel Catalytic Method for the Regeneration of Carbonyl Compounds from Oximes Using Aluminum Nitrate and NaBr as Catalyst.

Abstract A wide variety of aldoximes and ketoximes were regenerated to corresponding carbonyl compounds with Al(NO 3 ) 3 ·9H 2 O in presence of catalytic amounts of NaBr in CH 2 Cl 2 at room temperature.

Transitions of Organized Assemblies in Mixed Systems of Cationic Bolaamphiphile and Anionic Conventional Surfactants

The transition from vesicles to tubelike structures has been studied in mixed systems of cationic bolaamphiphile BPHTAB [biphenyl-4,4'-bis(oxyhexamethylenetrimethylammonium bromide)] and its oppositely charged conventional surfactants with transmission electron microscopy (TEM) and dynamic light scattering (DLS). This transition can be attributed to the fact that tube-like structures are more stable aggregates than vesicles because of the special molecular packing in the aggregates of the mixed systems. The effects of temperature and salt addition on this transition have also been investigated, and the rate of the transition was found to be strongly dependent on temperature. Addition of the appropriate amount of NaBr will accelerate the transition from vesicles to tube-like structures, but the vesicles will transform into micelles at higher salt concentration. Moreover, the micelle-vesicle transition can be realized by addition of n-octanol in the mixed system of BPHTAB/sodium caprate (SC) at higher salt concentrations.

Study of the parameters controlling the enantio-differentiating ability of asymmetrically modified solid catalysts for the hydrogenation of γ-ketoesters

The enantio-differentiating hydrogenation of γ-ketoesters was carried out over asymmetrically modified solid catalysts. The parameters affecting the enantiomer excess (ee) were investigated and the results were compared with those of the hydrogenation of methyl acetoacetate and 2-octanone reported in the literature. The highest value of enantiomer excess of 51% was attained for the hydrogenation of methyl 4-oxopentanoate over a tartaric acid (TA)-NaBr-modified reduced nickel catalyst prepared from nickel oxide. The amount of NaBr in the modification solution needed to be optimized according to the manufacturers of the nickel oxides. The addition of an appropriate amount of carboxylic acid to the reaction media increased the enantiomer excess of the hydrogenated products.

Azeotropic-like (congruent melting) phenomena of lamellar liquid crystals

The binary system of water and didecyldimethylammonium bromide (DDeAB), having a double hydrocarbon chain, was found to exhibit exhibit an azeotropic-like phase transition from lamellar liquid crystal to micellar solution. That is, the maximum limiting value of temperatures where the present system is allowed to exist in a lamellar liquid crystal corresponds to the socalled azeotropic point (AZP) or congruent melting point. At this temperature, the compositions of the liquid crystal and micellar solution phases become identical. Upon addition of a small amount of NaBr, the AZP shifts to a high temperature, but the point disappears above 0.375 wt% NaBr in water. The AZP is also increased by adding cholesterol. On the other hand, the transition enthalpies at AZPs are extremely small and almost constant, even if NaBr and cholesterol are added. The sharp DSC peak is observed in the presence of salt, whereas it is broad in the presence of cholesterol. It is considered that salt induces a closely packed state of the liquid crystal phase. Although cholesterol also has an ordering effect on the surfactant aggregates its hydrophobic property increases the phase transition temperature. The phase transition occurs due to a packing change of the hydrocarbon chains of DDeAB molecule from the lamellar to micellar states. The correlation between the movement of AZP and the phase behavior in the presence of salt is also discussed.

The Application of Radiochemical Techniques to the Study of the Interaction of Hair Fibers with Aqueous Solutions

Radioactive tracer techniques have proved to be uniquely adaptable to the study of the inter action of hair fibers with various aqueous solutions including dye baths. NaBr solutions, NaBr- HBr solutions, NaCl solutions, and an acid dye bath containing a sulfur-labelled acid dye for wool were used. It was found that appreciable amounts of NaBr were absorbed by hair from solution with a linear relationship existing between the equilibrium amount absorbed and the molarity of the treating solution. If acidic or basic solutions were used, additional absorption resulting from the well-known amphoteric properties of keratin was observed. In a preliminary experiment, the absorption of each of three componen's of an acid dye bath was followed by taking advantage of differences in radioactive behavior of the three species. Certain rate processes have also been followed.