A photoionization study of the van der Waals molecule C2H4 · HCl

The dissociation energy of the C₂H₄ · HCl van der Waals complex was determined to be 3.18±0.73 kcal mol^?1 by a dissociative photoionization technique. C₂H₄ · HCl was produced by free expansion of a 1:4 mixture of C₂H₄ in HCl and the clusters were ionized with tunable synchrotron radiation. The photoionization efficiency function of (C₂H₄ · HCl)⁺ from C₂H₄ · HCl was determined between 600 and 1,300 Å and the onset for (C₂H₄ · HCl)⁺ was established as 1,163±2 Å = 10.66±0.02 eV; these values give ΔH _f ⁰ (C₂H₄ · HCl) = ?10.7±0.7 kcal mol^?1 and ΔH _f ⁰ (C₂H₄·HCl⁺)=235.1±0.9 kcal mol^?1. A complex ion dissociation energyD ₀(C₂H₄ · HCl⁺) = ?0.3±0.9 kcal mol^?1 was calculated from the results. The major features on the PIE curve for C₂H₄ · HCl⁺ can be analyzed in terms of the known energetic features of C₂H ₄ ⁺ and HCl. An extended energy diagram for the C₂H₄ + HCl system is presented.     

Kinetics and possible mechanism of hydrogen chloride oxidation over supported copper-containing salt catalysts: II. Kinetics of HCl oxidation in the deacon and methane oxychlorination reactions over the CuCl2-KCl-LaCl3 catalyst

The kinetics of HCl oxidation at 350–425°C over the supported CuCl₂-KCl-LaCl₃ catalyst has been investigated using a gradientless technique. The HCl oxidation kinetics in the Deacon and methane oxychlorination reactions has been studied in order to substantially extend the \(Cl_2 \left( {P_{Cl_2 } } \right)\) partial pressure variation range. When the reaction rate is independent of P _HCl, HCl oxidation on the copper-potassium catalysts is described by the same rate equation, irrespective of whether the catalyst contains lanthanum or not. The introduction of lanthanum chloride increases the HCl oxidation rate by one order of magnitude. The rate equation obtained has significant advantages over the equation corresponding to the Kenney-Slama equation. The kinetic features of HCl oxidation over the lanthanum-containing catalyst, whether the process depends on P _HCl or not, can be explained in terms of the superposition of the Kenney-Slama dissociative mechanism and the catalytic mechanism suggested here. The role of lanthanum chloride in both HCl oxidation pathways is considered.     

Extraction and separation of60Co and65Zn halides from H2SO4 with TBP and amberlite LA-2

A systematic study is presented on the extraction of⁶⁰Co and⁶⁵Zn bromides and chlorides from H₂SO₄ with tri-n-butyl phosphate (TBP) and Amberlite LA-2. It has been found that the presence of a little HBr or HCl enhances the extraction of the two isotopes with both solvents. The extractions of⁶⁰Co and⁶⁵Zn have been studied as functions of the acidity (HBr, HCl or H₂SO₄) in the aqueous phase, and of the diluent and solvent concentrations in the organic phase. The presence of water-miscible alcohols or acetone enhances extraction. A suggested extraction mechanism is presented in the light of the obtained results.     

Separation of tin from some metals by extraction chromatography

Much attention has been devoted to Sn (IV) strongly retained on the TBP-Daiflon column from 2M HCl in extraction chromatography. The separations of Sn?Cu, Zn, As, Cd, Sb, Pb,¹¹³Sn-¹²⁵Sb,¹¹³Sn-^113mIn (^113mIn milking) and Sn?Hg?Fe were successfully achieved without any contamination. In the separations, except for the last, only tin was retained separately on the column upon passing the mixed solution. The daughter indium was eluted with 0.5M HCl. In the last separation, iron was eluted with 0.5 M HCl, tin with 0.1M HCl and mercury with 2M HNO₃, for these metals retained on the column. Radioactive tracers for tin, iron, mercury and antimony were used.     

Preparation and evaluation of PANI/PTT electromagnetic shielding fabric by in-situ chemical polymerization

To prepare the flexible and stretchable electromagnetic shielding (EMS) fabric with environmental stability, this paper uses polytrimethylene terephthalate (PTT) fabric as substrate, the aniline monomer as raw material, hydrochloric acid (HCl) as the doping agent, ammonium persulfate (APS) as the oxidant to produce polyaniline (PANI)/PTT electromagnetic shielding fabric by in-situ chemical polymerization. It studies the influence of APS and HCl concentration on the surface electrical resistance and the absorption loss of electromagnetic shielding fabric. It can be observed that an increasing APS and HCl facilitate the absorption and spread of PANI into PTT fabric to form a conductive network, and improve the absorption loss efficiency, while the excess APS and HCl will hinder the PANI polymerization. The high electrical conductivity and absorption loss of the PANI/PTT fabric are obtained at the concentration of An 0.4 M, APS 0.4 M, HCl 1.25 M, and polymerization reaction time 120 min. Meanwhile, in-situ polymerization of PANI does not introduce new impurities and destroy the molecular structure of PTT.     

Penning ionization electron spectrometry of hydrogen chloride

An electron spectrometric study has been performed on HCl using metastable helium and neon atoms as well as neon resonance photons. High resolution electron spectra were obtained with two different beam apparatuses for a mixed He(2¹ S, 2³ S) beam, a pure He(2³ S) beam, and, for the first time, state-selected pure Ne(3s ³ P ₂) and pure Ne(3s ³ P ₀) beams, and for NeI resonance photons. For the system He(2³ S)+HCl the vibrational populationsP(υ′) of the formed HCl⁺ (X ²∏ _i , υ′) and HCl⁺ (A ²Ω⁺, υ′) ions are found to differ from the Franck-Condon factors for unperturbed potentials, indicating slight bond stretching in HCl upon He(2³ S) approach. For He(2¹ S)+HCl the vibrational peak shapes and vibrational populations are substantially different from the He(2³ S) case, pointing to an additional, charge exchanged interaction (He⁺+HCl^?) in the entrance channel of the former system. For the first time, we have detected the electrons in both the He(2¹ S)+HCl and He(2³ S)+HCl spectra associated with the major mechanism for the formation of Cl⁺ ions: energy transfer to repulsive HCl** Rydberg states, dissociating toH(1s) and autoionizing Cl**(¹ D ₂ nl) atoms. For both Ne(³ P ₂)+HCl and Ne(³ P ₀)+HCl, the populationsP(υ′) of both final molecular states HCl⁺ (X, A) agree closely with the Franck-Condon factors at the average relative collision energyē _coll=55 meV and, for HCl⁺ (A ²Ω⁺), also atē _coll=130 meV.     

Effect of Cl substituent in the aromatic tetracycline ring on its reactivity with solvated electrons

Decomposition yields of tetracycline hydrochloride /TC.HCl/ and chlorotetracycline hydrochloride /ClTC?HCl/ in methanol solution saturated with Ar or N₂O were determined. Rate constants of the reaction e_s with some antibiotics were obtained: $$\begin{gathered} k/e_s^ - + ClTC \cdot HCl/ = 2 \cdot 49 \times 10^8 dm^3 \cdot mole^{ - 1} \cdot s^{ - 1} ; \hfill \\ k/e_s^ - + TC \cdot HCl/ = 2 \cdot 86 \times 10^8 dm^3 \cdot mole^{ - 1} \cdot s^{ - 1} \cdot \hfill \\ \end{gathered} $$ On the basis of the diffence between decomposition yields: ΔG=G_?TC.HCl^?G?ClTC.HCl′ 7-C?Cl group decomposition yield and the rate constant $$k/e_s^ - + Cl - C - 7/ = 7 \cdot 94 \times 10^8 dm^3 \cdot mole^{ - 1} \cdot s^{ - 1} $$ were determined. It was demonstrated by¹H NMR that the radical formed by degradation of 7-C?Cl group is recombined with the H atoms leading to ClTC.HCl being converted into tetracycline hydrochloride /TC.HCl/.     

The role of octanol in the extraction of hydrochloric acid by trilaurylamine dissolved in benzene

The extraction of hydrochloric acid by trilaurylamine (TLA) dissolved in benzene was studied in the presence and in absence of n-octanol. The extraction of HCl was found to be enhanced by the addition of octanoi to the organic phase. In order to explain this effect by means of the law of mass action, the systems TLA-HCL-benzene and n-octanol-HCl-benzene as well as TLA-octanol-benzene were also studied. It was found that TLA reacts with octanol to form a complex, TLAROH, while the octanol itself associates in benzene to form dimers and tetramers, although it does not extract HCl alone from the dilute solutions used in the present study. The enhancement of the extraction of HCl by TLA upon the addition of n-octanol could be described by the formation of the species TLA·ROH·HCl and its stability constant was determined.     

On the determination of HCl+ (A,v′) vibrational populations from HCl+ (A→X) fluorescence spectra: direct comparison between photoionization and penning ionization

Using a beam apparatus, we have measured the HCl⁺ (A,v′→X,v″) fluorescence spectra of HCl⁺ (A,v′) ions formed in HeI (58.4 nm), and NeI (73.6 nm) photoionization and, for the first time, in He (2³ S) Penning ionization under single collision conditions with a wavelength bandwidth around 1 nm. In addition, we have studied Ne (3s ³ P _{2, 0}) Penning ionization of HCl at three different collision energies. The procedure and the problems in extracting HCl⁺ (A,v′) vibrational populations from the data are discussed in some detail. Thedirect comparison of photoionization and Penning ionization data allows definitive conclusions to be drawn on the question whether final state interactions in the Penning reaction change the “nascent” vibrational population (determined by electron spectrometry); for He (2³ S)+HCl, such changes are shown to be absent within the experimental uncertainty (<±10%). For Ne (3s ³ P _{2, 0})+HCl, the HCl⁺ (A,v′=0, 1) populations are also found to be close to those measured by electron spectrometry and essentially independent of collision energy in the range 34–96 meV. From measurements of the fluorescence intensity as a function of HCl density, we have evidence for a fast loss of HCl⁺ (A,v′) ions in collisions with HCl (rate constant around 5·10^?9 cm³s^?1).     

Solvent extraction of hafnium(IV) by TBP and topo from acidic organic-aqueous solutions

Tracer concentrations of Hf(IV) were extracted by 60% TBP solution in benzene from 5M HClO₄, 5M HCl, 6M HNO₃ and 8M H₂SO₄ solutions, and by 1·10^?4 M TOPO solution in benzene from 2M HClO₄ and 2M HCl solutions in the presence of a variety of organic solvents miscible with the aqueous phase. Whereas for TBP these solvents caused an increase of HF(IV) extraction, an opposite effect was observed for TOPO. The results were discussed from the point of view of various solute-solvent and solvent-solvent interactions.     

Influence of HCl on the stability of liquid lamellae between two colliding bubbles in aqueous solutions ofn-fatty acids

The effect of HCl on life time of liquid lamellae created between two colliding bubbles in aqueous solutions ofn-fatty acids were studied. The results show, that the addition of HCl has a pronounced influence on life time of the lamellae. At low fatty acid concentration the lifetime of the lamellae in the acidified solution is higher than in the nonacidified solution, but at higher fatty acid concentration the effect reverses. The analysis of these experimental results show that the characteristic influence of HCl on lamellae lifetime can be explained by the formation of distinct association states of the fatty acids in the liquid phase at different concentration ranges. The results are discussed with respect to bubble coalescence in gas-liquid contactors.     

Isolation and alpha-particle spectrometric determination of238Pu and239,240Pu in sediments

A simple method is described for the isolation and determination of plutonium isotopes in sediments. The method involves leaching of sample with nitric acid and subsequent separation of plutonium on an anion-exchange column. Major matrix elements and several potential radiochemical interferences are removed during 8M HNO₃ sample loading on the column. Thorium is removed by thorough washing with 10M HCl. Plutonium (IV) is eluted with 4M HCl. Source for alpha-particle spectrometry is prepared by LaF₃ coprecipitation technique at which stage a complete separation from uranium(VI) is also achieved. The entire analytical procedure is completed in about two days.     

Kinetics and possible mechanism of hydrogen chloride oxidation over supported copper-containing salt catalysts: I. Kinetics of HCl oxidation in the deacon and methane oxychlorination reactions over a copper-potassium salt catalyst

The kinetics of HCl oxidation at 350–425°C over a (CuCl₂-KCl)/support catalyst in two complementary processes—Deacon and methane oxychlorination reactions—has been investigated using a gradientless technique. This has allowed the range of \(P_{Cl_2 }\) in the reaction mixture to be markedly extended. New kinetic features of HCl oxidation under conditions such that this process does and does not depend on P _HCl have been discovered. The kinetic equations obtained in this study fit experimental data in a wider range of conditions than the equations proposed earlier. The results of this study suggest the existence of two HCl oxidation pathways in the Deacon reaction.     

Transference numbers and phenomenological transport coefficients for concentrated aqueous hydrochloric acid solutions at 25°C

The transference numbers of HCl in water at 25°C have been determined up to 8 mol-kg^?1 by using cells with transference. The problem of the solubility of AgCl from Ag/AgCl electrodes was avoided by employing dilute chlorine gas/iridium electrodes for T _H and hydrogen gas/platinum electrodes for T _Cl . The sums of the independently measured T _H and T _Cl values never differed from unity by more than 0.9%. The cation constituent transference number of HCl was also measured at 1M by the recently modified moving boundary method, but at higher concentrations the Soret effect produced unacceptably large current dependences. Combination of these transference numbers with literature conductances, diffusion coefficients and activity coefficients led to a new set of phenomenological transport coefficients l _ij . The resulting curve for l₁₂/c vs. c behaves more normally than did the curve based on previous transference numbers.     

Sorption of Ponceau 4R anionic dye from aqueous solutions on aluminum oxide and polyurethane foam

The sorption of Ponceau 4R (E-124) anionic dye on polyurethane foam based on ethers and γ-Al₂O₃ from aqueous solutions is studied. It is established that sorption is highest in the range of 0.5 M HCl, pH 2 on polyurethane foam and 0.2 M HCl, pH 6.5 on γ-Al₂O₃. Under optimum conditions, the degrees of recovery on polyurethane foam and γ-Al₂O₃ are 20–30 and 70–85%, respectively. A possible scheme of interactions between the dye and the surfaces of sorbents is proposed.     

Activity coefficient of hydrochloric acid in aqueous solutions of sodium chloride

Electromotive-force measurements of the cell $$Pt;H_2 \left( {g,1{\text{ }}atm} \right)|HCl\left( {{\text{m}}_A } \right),NaCl\left( {{\text{m}}_B } \right)|AgCl;Ag$$ have been made at temperatures between 5 and 45°C at values ofm _A+m _B of 0.1, 0.3809, 0.6729, and 0.8720 mole-kg^?1. The activity coefficients of HCl in HCl/NaCl mixtures and the Harned coefficients α₁₂ have been obtained. The change of α₁₂ with total molality is consistent with the existence of binary interactions between H⁺ and Na⁺ ions. The linear variation of the relative partial molal heat content with the fraction of NaCl in the mixture suggests that an analog of the Harned rule exists for this thermodynamic quantity.     

TiO2 and TiO2/SiO2 nanoparticles obtained by sol–gel method and applied on dye sensitized solar cells

In this work we show the synthesis and characterization of TiO₂ and TiO₂/SiO₂ nanoparticles synthesized by sol–gel method using HF and HCl as catalysts. The obtained nanoparticles were analyzed by N₂ adsorption–desorption isotherms, transmission electronic microscopy, Ultraviolet–visible spectroscopy and X-ray diffractometry. Mesoporous, homogeneously polycondensed TiO₂/SiO₂ materials, containing nanocrystalline anatase phase with band gap similar to pure titania were obtained. Films of the powdered oxides were applied to assemble dye sensitized solar cells that presented electrical parameters, Fill Factor and efficiencies similar to devices obtained by only TiO₂. The sol–gel route arises as an alternative way to prepare TiO₂/SiO₂ materials for solar cells.     

Separation of metallic impurities from uranium by anion exchange on Dowex 1×8 resin

The separation of metallic impurities from uranium by anion exchange with a Dowex 1×8 resin has been investigated. The following elements can be quantitatively separated from 400 mg uranium using a 1 cm diameter 15 or 30 cm long column. The elements Ag, Al, Ba, Ca, Cr, Cs, K, Mg, Mn, Na, Ni, Rb, REE, Sc, Th, Ti and Y can be separated by eluting the elements with conc. HCl. Uranium is retained by the resin. Al, Ca, Cd, Co, Cr, Cu, Fe, Mg, Mn, Na, REE and V can be separated by eluting with 0.01 N H₂SO₄. Uranium is retained by the resin. Cd and Zn can be separated by first eluting uranium with 0.5 N HCl and then eluting Cd and Zn with 1 N NH₃. Hf, Zr and V can be separated by eluting with 5 N HCl but some uranium contamination is unavoidable.     

Molecular beam study of the system Kr + HCl

Angular distributions of HCl scattered off Kr have been measured at collision energiesE ranging from 66.3 to 208.7 meV. The curves exhibit a clearly resolved damped rainbow structure. In addition time-of-flight distributions of scattered HCl were measured indicating significant energy transfer. To a part of these data (E=99 meV) the parameters of the M5 potential energy surface of Hutson and Howard [3] were fitted using the infinite order sudden approximation (IOSA) and quasi classical trajectories (QCT). A comparison of QCT and IOSA results suggests applicability of the IOSA to the present system atE=99 meV. We find a well depth of ?31.8 meV (compared to Hutson and Howard's value of ?26.5 meV) at the collinear Kr ... HCl conformation and strong indication for the existence of a secondary potential minimum at the collinear Kr ... ClH conformation. The analysis of the angular distributions based on a one channel scattering calculation leads to an isotropic potential similar to the full potential energy surface cut along the 90°-conformation rather than to the spherical average or spherical limit of the surface.     

Chemical separation of molybdenum from uranium and fission product nuclides

A very rapid method for the separation of molybdenum(VI) from neutron irradiated uranium and its fission products is described. The procedure is based on the selective extraction of molybdenum(VI) by a 0.1M solution of 2-hexylpyridine in benzene from 4M HCl+0.04M KSCN. Decontamination factors were estimated to be >10⁴ for the radionuclides of niobium, zirconium, ruthenium, lanthanum, cerium, promethium, yttrium, strontium and barium.