XRD characterization of the ashes from a burned cellulosic fabric impregnated with magnesium bromide hexahydrate as flame-retardant

The effect of magnesium bromide hexahydrate [MgBr₂·6H₂O] as a nondurable finish on the flammability of 100% cotton fabric, (woven construction, massing 150 g m⁻²) has been investigated. The laundered bone-dried, massed fabrics were impregnated with various concentrations of the aqueous above-mentioned salt solutions by means of squeeze rolls and drying in an oven at 110°C for 30 min. The specimens were then cooled in a desiccator, re-massed with an analytical balance and kept under standard conditions before the fulfillment of the vertical flame spread test. After several experiments the optimum add-on values to impart flame-retardancy expressed in g anhydrous magnesium bromide hexahydrate per 100 g fabric were determined to be about 5.6%. The ashes of the treated specimens were subjected to X-ray diffraction analysis (XRD), and the result was compared with data for pure MgO powder and/or MgBr₂ specimens. Consequently the existence of MgO was detected in the ashes.     

Dynamic and controlled rate thermal analysis of attapulgite

We have investigated the effect of magnesium chloride hexahydrate [MgCl₂·H₂O] as a nondurable finish on the flammability of 100% woven cotton fabric, (plain construction, with a density of 144 g m⁻², the number of yarns 21/10 mm). The laundered bone-dried, massed fabrics were impregnated with suitable concentrations of aqueous solution of the above-mentioned salt, by means of squeeze rolls. They were then dried horizontally in an oven at 110°C for 30 min. The optimum add-on value after the fulfillment of vertical flame spread test to donate flame-retardancy onto cotton fabric was obtained to be in the range of 6.73–8.30 g of the salt per 100 g fabric. Thermogravimetry (TG) of pure cotton, treated cotton and the salt was accomplished, and their TG curves were compared and commented. The results obtained are in favor of the ‘gas dilution theory’, chemical action theory and also in compliance with the ‘free radical theory’. The formation of sal ammoniac was proven by sprinkling concentrated ammonia upon the inflamed treated specimen.     

TG studies of synergism between red phosphorus (RP)–calcium chloride used in flame-retardancy for a cotton fabric favorable to green chemistry

The combined effect between calcium chloride and red phosphorus (RP) on the flame-retardancy of a cotton fabric (woven construction massing 152 g/m²) has been studied in this work. The laundered bone-dried massed samples were impregnated with suitable concentrations of individual aqueous red phosphorus suspensions and/or calcium chloride solutions and some bunches were impregnated with appropriate admixed solutions of the both chemicals. An acceptable synergistic effect was then experienced by using an admixed bath containing 0.20 F red phosphorus and 0.20 M calcium chloride for impartation of flame-retardancy to a cotton fabric. By using a vertical flame spread test the optimum mass of the mixture needed to donate flame-retardancy was obtained to be about 5.88 g anhydrous additives per 100 g dry fabric. Thermogravimetry (TG/DTG) results concerning untreated and treated cotton fabrics at the optimum addition were obtained and their curves were compared and commented, fortifying the flame spread tests outcomes. It can be deduced that the applied treatment functioned as a catalyst at the combustion’s temperature of the polymeric substrate and, thermosensibilized the combustion process. This synergism is in favor of green chemistry as well as the economical and industrial view points.     

在NaCl和SCN~-存在下浮选铜(Ⅱ)间接测定十六烷基三甲基溴化铵

研究了NaCl和NH4SCN浮选Cu(Ⅱ)间接测定十六烷基三甲基溴化铵的新方法。在水溶液中,Cu(Ⅱ)与SCN-和CTMAB缔合生成沉淀,在NaCl存在下,此沉淀被浮选。实验表明,Cu(Ⅱ)的浮选率与CTMAB的量在3.6~54.7 mg/L范围内呈良好的线性关系。CTMAB的检出限为1.8μg/mL。方法已用于合成水样和自来水中CTMAB的测定。     

Detection of copper(II) sulfate’s uniformity and its thermal behavior in flammability of cotton fabric

Blue vitriol (copper(II) sulfate pentahydrate), CuSO₄·5H₂O has been chosen and investigated for its effectiveness as a flame-retardant, when impregnated into cotton fabric (cotton with a plain structure; woven 180 g m⁻², with 22 numbers of yarns per 10 mm). Using the vertical flame test, the extent of resistance to burning of the specimens has been determined. The impregnation was accomplished via dipping and stirring of bone-dried, weighed fabrics into the individual and suitable concentrations of the salt at room temperature. Afterwards the samples were squeeze rolled and dried horizontally at 110°C for 30 min in an oven and cooled in a desiccator and reweighed with an analytical precision. They were then kept under ordinary conditions overnight prior the fulfillment of the vertical flame test. The efficient quantities of the aforesaid salt expressed in g per 100 g dry fabric have been determined in an average figure of 12.75%. Estimation of uniformity in a selected sample was carried out via a spectrophotometer and results are in favor of the heterogeneous distribution of the salt in the fabric’s middle sectors. However initial and final parts of specimen showed to be rather uniformed. Thermogravimetric analysis of the pure cotton and the treated ones with insufficient and effective amounts of the salt were fulfilled and their thermograms were compared and commented. The results obtained for the effect of copper(II) sulfate comply with ‘The Dust or Wall Effect Theory’. This action is also assigned to the condensed phase retardation.     

Thermal parameters associated to micellization of dodecylpyridinium bromide and chloride in aqueous solution

Electrical conductivity of aqueous solutions of dodecylpyridinium chloride and bromide have been determined. From these data the critical micelle concentration (cmc) was determined. The thermal properties as standard Gibbs free energy, enthalpy and entropy of micellization was estimated from a uncharged-phase separation model and enables to obtain another properties like heat capacity of micellization and the relevant parameters in the minimum of temperature dependence of cmc. The enthalpy-entropy compensation was shown for the studied compounds. This revised version was published online in July 2006 with corrections to the Cover Date.     

Fluorescence enhancement effect for the determination of DNA with calcein-cetyl trimethyl ammonium bromide system

A new spectrofluorimetric method was developed for the determination of trace amounts of DNA using the calcein as a fluorescent probe. In the presence of appropriate amounts of the cationic surfactant cetyl trimethyl ammonium bromide (CTAB), the anionic dye calcein dimerizes. The weak fluorescence intensity of the dimer was enhanced by adding DNA at pH 6–7. The interaction between calcein–CTAB and DNA was studied on the basis of this behavior and a new method was developed for determining DNA. Under the optimal conditions, the enhanced fluorescence intensity was in proportion to the concentration of DNA in the range of 4.0 × 10⁻⁶ to 8.0 × 10⁻⁵ g L⁻¹ for fsDNA and thermally denatured ctDNA (4.5 × 10⁻⁶ to 9.0 × 10⁻⁵ g L⁻¹). The detection limits (S/N = 3) were 2.0 × 10⁻⁶ and 2.2 × 10⁻⁶ g L⁻¹, respectively. This method was used for determining the concentration of DNA in synthetic samples with satisfactory results.     

CO2 capture from binary mixture via forming hydrate with the help of tetra-n-butyl ammonium bromide

Hydrate formation rate and separation effect on the capture of CO2 from binary mixture v/a forming hydrate with 5 wt% tetra-n-butyl ammonium bromide (TBAB) solution were studied.The results showed that the induction time was 5 min,and the hydrate formation process pressure of 7.30 MPa.The CO2 recovery was about 45% in the feed pressure range from 4.30 to 7.30 MPa.Under the feed pressure of 4.30 MPa,the maximum separation factor and CO2 concentration in hydrate phase were 7.3 and 38.2 tool%,respectively.The results demonstrated that TBAB accelerated hydrate formation and enriched CO2 in hydrate phase under the gentle condition.     

Volume behavior of mixed micelles of dodecyltrimethylammonium chloride and bromide

Densities of aqueous solutions of mixtures of dodecyltrimethylammonium chloride (DTAC) and dodecyltrimethylammonium bromide (DTAB) have been measured as a function of total molality at constant composition and the apparent molar volumes of the mixtures were derived from the density data. The partial molar volumes of monomeric surfactant mixtures, the molar volumes of mixed micelles, and the volumes of formation of mixed micelles were evaluated and are compared with those for decyltrimethylammonium bromide (DeTAB) and DTAB mixtures. The partial molar volumes of monomeric surfactant mixtures and the molar volumes of mixed micelles are observed to depend linearly on the monomer and micelle compositions, respectively. Although the volume of formation of mixed micelles of the DeTAB-DTAB mixture depends on the micellar composition, that of the DTAC-DTAB mixture is observed to be almost independent of the micellar composition. This suggests that the volumes of the counter ions in the micellar solutions are almost equal to those in the monomeric solutions.     

溴化铵改性膨润土脱除气态单质汞的特性及机理分析

采用溴化铵对钠基膨润土进行改性制得脱汞吸附剂,在固定床实验装置上对所制备的吸附剂进行脱汞性能测试。脱汞实验结果表明,钠基膨润土较钙基膨润土在脱汞性能上提高不大,而溴化铵改性的钠基膨润土(Br-Ben/Na)脱汞性能得到明显提高,脱汞效率达到97.7%。吸附温度的升高有利于对Hg0的脱除,在140℃下,10%Br-Ben/Na吸附剂的脱汞率能长时间保持在90%以上,说明在此吸附过程中化学吸附占主导性作用。通过N2吸附/脱附、X射线衍射(XRD)、元素分析仪和傅里叶变换红外光谱(FT-IR)分析等结果表明,改性后的膨润土比表面积下降,平均孔径增大;铵根离子进入到膨润土的层间置换出层间钠离子,煅烧活化过程中层间的铵根离子并未分解,而在层间与膨润土结合为某吸附活性组分协助Br-与Hg0反应,提高了膨润土的脱汞性能。     

氯化钠-硫氰酸铵-氯化十四烷基吡啶体系浮选分离铜

在水溶液中Ｃｕ(Ⅱ )与硫氰酸铵、氯化十四烷基吡啶形成不溶于水的三元缔合物 ,在少量氯化钠存在下此三元缔合物沉淀浮于水相上层并与水分成界面清晰的两相 ,分相过程中Ｃｕ(Ⅱ )被定量浮选。而Ｆｅ(Ⅲ )、Ｃｏ(Ⅱ )、Ｎｉ(Ⅱ )、Ｍｎ(Ⅱ )、Ｃｄ(Ⅱ )等离子在该体系中不能被浮选 ,借此可实现Ｃｕ(Ⅱ )与这些离子的分离。1　实验部分1 1　仪器与试剂氯化钠 (Ａ .Ｒ .,洛阳市化学试剂厂 ) ;1 .0×1 0 - 2 ｍｏｌ·Ｌ- 1 氯化十四烷基吡啶溶液 (ＴＢＰＣ)(ｐａｃｋｅｄｉｎＳｗｉｔｚｅｒｌａｎｄ) ;0 .2ｍｏｌ·Ｌ- 1 硫氰酸铵标准溶液按文…     

Reaction kinetics of glycidyl trimethyl ammonium chloride and chitosan in 1-allyl-3-methylimidazolium chloride

The modification of chitosan in ionic liquids through homogeneous reactions has advantages including shorter time and simple post-treatment and the generated chitosan derivatives have high degrees of subsititution and good reproducibility. In this paper, we studied the reaction kinetics of glycidyl trimethyl ammonium chloride and chitosan in 1-allyl-3-methylimidazolium chloride. Chitosan concentration, temperature, and reaction time were studied to determine their influence on reaction kinetics. The results indicated that reaction rate increased with increases of both chitosan concentration and temperature. A first-order kinetics equation was generated, where the relationship between reaction rate constant and temperature was determined.     

Enthalpy and heat capacity parameters of ammonium bromide interaction with hexamethylphosphotriamide in water

Thermal effects of solution of ammonium bromide in hexamethylphosphotriamide (HMPT)-water mixtures at 4° C, 15°C, and 46°C in the region of minor additions of the nonaqueous component were investigated for the first time by calorimetry. Variations of heat capacity in the course of solution were calculated using previous data for 25°C and 40°C. The curves of the heat capacity of solution (transfer) and temperature variation of transfer entropy versus composition have a minimum near the region of the existence of the 1:20 HMPT:water clathrate. The enthalpy, heat capacity, and temperature variations of the entropy coefficients of electrolyte amide pair and three-particle interactions in water were calculated in terms of MacMillan-Mayer theory. Within the framework of the group additivity method it is shown that the heat capacity coefficient of the bromide ion-HMPT pair interaction is negative and dictates temperature variations of enthalpy for ammonium bromide and tetraalkylammonium interactions with HMPT in water.     

Interactions of Cationic Surfactant Cetyl-trimethyl ammonium bromide with Ammonium nitrate: Surface and Thermodynamic Studies

The study of interactions between surfactant and salt in aqueous solutions has attracted significant interest in recent years because of their widespread applications and relatively complex behavior. This work reports the systematic study of surface phenomenon and self-aggregation behavior of cationic surfactant cetyltrimethyl ammonium bromide (CTAB) with ammonium nitrate (NH\begin{document}$ _4 $\end{document}NO\begin{document}$ _3 $\end{document}) salt. Surface and thermodynamic properties of cationic surfactant CTAB with NH\begin{document}$ _4 $\end{document}NO\begin{document}$ _3 $\end{document} were investigated at different temperatures using different techniques such as conductometry and surface tensiometery. The surface tension measurement was carried out to find out the critical micelle concentration, free energy of adsorption, free energy of micellization, minimum area per molecule, and surface excess concentration. The study reveals that the process of micellization is spontaneous and exothermic in nature. Conductance measurement was carried out to determine critical micelle concentration, degree of ionization and degree of counter ion binding. Addition of NH\begin{document}$ _4 $\end{document}NO\begin{document}$ _3 $\end{document} to the surfactant solutions increase the values of degree of ionization and degree of counter ion binding, although it lowers the values of critical micelle concentration showing that the process of micellization is more favorable and spontaneous. The study is very helpful to develop better understanding about interaction between electrolyte and surfactant, which are used in many applications and in different processes (e.g., pharmaceutical, industrial foaming, drug solubilization, oil recovery, and medium for metal nanoparticle formation).     

Radical-type addition of benzyl bromide to vinyl chloride: the kinetics and activation energy of the process

Radical telomerization of vinyl chloride with benzyl bromide and the competitive reaction of benzyl bromide with vinyl chloride and trimethylvinylsilane have been studied. The relative rate constant for the addition of C₆H₅C · H₂ to vinyl chloride,k _rel (with respect to trimethylvinylsilane), is close to unity, whereas the activation energy of the addition of C₆H₅C^.H₂ to vinyl chloride is considerably lower (by 7 kcal mol^–1) than in the reaction involving trimethylvinylsilane. The possible fragmentation of the radical-adduct C₆H₅CH₂CH₂C^.HCl was suggested as one of the possible reasons of underestimation ofk _rel. The activation energy was estimated by the MPDO/3 method.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 886–888, May, 1993.     

Higher hydrates of lithium chloride,lithium bromide and lithium iodide

For lithium halides, LiX (X = Cl, Br and I), hydrates with a water content of 1, 2, 3 and 5 moles of water per formula unit are known as phases in aqueous solid–liquid equilibria. The crystal structures of the monohydrates of LiCl and LiBr are known, but no crystal structures have been reported so far for the higher hydrates, apart from LiI·3H₂O. In this study, the crystal structures of the di‐ and trihydrates of lithium chloride, lithium bromide and lithium iodide, and the pentahydrates of lithium chloride and lithium bromide have been determined. In each hydrate, the lithium cation is coordinated octahedrally. The dihydrates crystallize in the NaCl·2H₂O or NaI·2H₂O type structure. Surprisingly, in the tri‐ and pentahydrates of LiCl and LiBr, one water molecule per Li⁺ ion remains uncoordinated. For LiI·3H₂O, the LiClO₄·3H₂O structure type was confirmed and the H‐atom positions have been fixed. The hydrogen‐bond networks in the various structures are discussed in detail. Contrary to the monohydrates, the structures of the higher hydrates show no disorder.     

Enthalpies of solution oft-butyl chloride and bromide and carbon tetrachloride and tetrabromide in alcohols

Standard enthalpies of solution of t-BuX and CX₄ (X=Cl and Br) in several alcohols are reported as measured by a calorimetric method. The corresponding transfer functions from the gas phase were calculated.     

Enthalpies of solution oftert-butyl chloride and bromide in butanols and pentanols

The solution enthalpies at infinite dilution, _sH°, of the compounds t-BuCl and t-BuBr in 2-BuOH, i-BuOH, 2-PeOH and t-PeOH have been determined by solution calorimetry, between 25 and 40°C. The new results are discussed and compared with published values for other isomeric alcohols.     

Physicochemical investigation on interactions of some amino acids with aqueous tetra-butyl ammonium bromide solution at 298.15 K

Apparent molar volumes, viscosity B-coefficients, and apparent molar isentropic compressibilities of glycine, L-alanine, L-valine and L-leucine in 0.062, 0.125 and 0.256 mol kg^?1 aqueous tetra-butyl ammonium bromide (TBAB) solution have been determined at 298.15 K from their experimental density, flow time and sound speed measurements, respectively. The standard partial molar volumes and compressibilities are used to calculate the corresponding volume of transfer at infinite dilution, from water to aqueous TBAB solutions. The linear correlation of partial molar volumes for a homologous series of amino acids has been utilised to calculate the contribution of charged end groups and other alkyl chains of the amino acids to partial molar volumes. The hydration numbers of amino acids have also been determined. Viscosity B-coefficients have been calculated using the Jones–Dole equation. The values of the charged end groups contribution to the viscosity B-coefficients of the amino acids are calculated.     

Volumetric Properties of Tetra-n-butyl ammonium bromide in Aqueous Solutions of Magnesium sulphate in the Temperature Range 298.15 to 318.15K and under the Atmospheric Pressure

Density and sound speed measurements have been carried out for the ternary systems consisting of tetra-n-butyl ammonium bromide (TBAB) in 0.1 m aqueous magnesium sulphate heptahydrate (MgSO₄.7H₂O)-water over the full range of composition from T = 293.15 to 318.15 K by using volumetric method. Using this experimental data, various physical and thermodynamical parameters such as adiabatic compressibility, apparent molal compressibility, apparent molal volume, apparent and limiting partial molar volumes of the electrolytes and ions in these mixtures have been evaluated and split into respective ionic contributions. The results have been discussed in terms of ion–ion and ion–solvent interactions occurring between TBAB and aqueous MgSO₄ solutions. Further, structure making/breaking behaviour of MgSO4 has been reported in terms of sign of the partial molar expansibility at infinite dilution.