Carbon Tetrachloride Vapor Research Articles

Изучение процесса адсорбции паров бензола активированными углями марок АР-А, АР-Б и углями компании Baojun Activated Carbon

We presented the results of a study of the adsorption capacity of domestic activated carbon grades AR-A and AR-B, and a coal from Baojun Activated Carbon (China) with respect to benzene vapor. All used adsorbents are designed to purify air from vapors of volatile organic compounds, but differ in production technology and physicochemical characteristics. It has been established that the efficiency of Baojun Activated Carbon’s activated carbon in the adsorption of benzene vapor is higher than that of domestic samples of AR-A and AR-B grades. At the same time, among foreign-made coal, the most effective sample was Baojun 4.0/90, which has a high adsorption capacity, declared in relation to carbon tetrachloride vapor. It has been experimentally shown that in all cases the kinetics of the adsorption process is well described by the Ho and MacKay pseudo-second order equation. Similar results were obtained using the Morris --- Weber model, which takes into account the role of diffusion processes in the adsorption of benzene vapor by activated carbons. The use of the Lagergren equation and the simplified Elovich model for processing experimental data showed less significant results

Label-free high performance optical CCl4 sensor based on MIL-101(Cr) photonic crystals

Label free detection with high sensitivity, selectivity and reliability is crucial for monitoring carbon tetrachloride (CCl4) vapor, which is a kind of hazardous vapor to human health even at low concentration. In this work, we synthesized the MIL-101(Cr) through a hydrofluoric acid-free (HF-free) method and proposed a label-free high performance optical refractive index CCl4 vapor sensor based on MIL-101(Cr)/TiO2 one-dimensional photonic crystals (1DPC). The application of the MIL-101(Cr)/TiO2 1DPC in CCl4 vapor optical detection was investigated due to the excellent selectivity and ultrahigh adsorption capacities of MIL-101(Cr) for CCl4 vapor. The results illustrate that the MIL-101(Cr)/TiO2 1DPC vapor sensor shows high sensitivity of 0.11 nm/ppm with a good linear relationship in the concentrations range of 0–100 ppm CCl4 vapor and great selectivity with the value of selectivity(S) varied from 2.63 to 18 comparing CCl4 vapor with toluene (C7H8), acetone (C3H6O), n-hexane (C6H14) and dichloromethane (CH2Cl2) vapor. Meanwhile, the MIL-101(Cr)/TiO2 1DPC sensor presents a fast optical response and recovery time of 1.2 s and 12.1 s with exceptional repeatability and reliability for 100 ppm CCl4 vapor detection, which are important for practical applications.

Decomposition of сarbon tetrachloride under the action of a dielectric barrier discharge of atmospheric pressure in an oxygen atmosphere

In this study, the process of decomposition of carbon tetrachloride (CCl4) vapor in oxygen DBD at atmospheric pressure and its kinetic regularities have been studied. In the course of the experiments, it was shown that the efficiency of the decomposition of carbon tetrachloride in DBD can reach 100%. Depending on the conditions of the experiments, the effective rate constants were equal to (0.16–0.59) s−1, and the decomposition energy yields were (0.001–0.012) molecules per 100 eV of the inputed energy. The main decomposition products were CO2 and Cl2 molecules. The formation of a solid on the internal electrode of the reactor was also found. The substance contains atoms of carbon, oxygen, chlorine (C:O:Cl) = 1:0.38:0.01, as well as hydrogen atoms. The substance also contains functional groups –CH, –CH2, –OH and dimers of carboxylic (chlorocarboxylic) acids. Based on the solution of the Boltzmann equation for electrons, it is shown that for the compositions of a gas containing O2 molecules, ССl4, and decay products, the kinetic and transport characteristics of electrons are the same as in a pure oxygen discharge. Using the kinetic characteristics of electrons and the reaction rate constants the mechanisms of reactions leading to the found reaction products are proposed. It was shown that the primary reaction of destruction is the reaction of dissociation of CCl4 by electron impact, leading to the formation of CCl3• and Cl and the reaction with the O (1D) atom, as a result of which CCl3• and ClO• are formed.

Carbon tetrachloride vapor sensing based on ZIF-8@ZnO/TiO2 one-dimensional top-defect photonic crystals

This paper is devoted to an investigation of the carbon tetrachloride (CCl4) sensing properties of the microporous zeolitic-imidazolate framework-8 (ZIF-8) composite with one-dimensional top-defect photonic crystals(1DTDPC) structure. We propose the ZIF-8@ZnO/TiO2 1DTDPC gas sensor for the first time derived from ZIF-8 composite (ZIF-8@ZnO) and titanium dioxide (TiO2) by a spin-coating method. Comparing with the ZIF-8/TiO2 1DTDPC, the ZIF-8@ZnO/TiO2 1DTDPC shows the better quality and sensing property with the sensitivity to be 0.008 nm/ppm toward the water (H2O) vapor. It is found that the ZIF-8@ZnO/TiO2 1DTDPC exhibit a highly selective detection toward carbon tetrachloride (CCl4) vapor during the experiment of the carbon tetrachloride (CCl4), dichloromethane(CH2Cl2), methanol (CH3OH), formaldehyde (HCHO), and water(H2O) vapor. The relationship between the maximum reflectance peak’s shift of the ZIF-8@ZnO/TiO2 1DTDPC sensor and the increasing concentration of CCl4 vapor is investigated to be linear with the sensitivity of 0.05 nm/ppm, and the optical response time is obtained to be ∼300 ms with the concentration of 320 ppm. Moreover, the great reversibility and stability were also demonstrated, which are beneficial for practical applications.

Modification and functional properties of detonation nanodiamond

Original termination of the detonation nanodiamond (DND) was changed by active chemical media interaction. Oxidation in boiling chloric acid, by hydrogen and chlorination by carbon tetrachloride vapor was applied. FTIR, TGA, and photoluminescence techniques revealed the DND functional termination changing. At hydrogenation treatment monofunctionally of the surface demonstrated. The totality of presented results demonstrates the possibility of substantial and controlled changes in the DND functional properties, for their subsequent use in the self-organization processes, at nanocomposites preparation and for other aims.

Mechanisms of synthesis reaction of pure anhydrous indium(III) chloride

The chlorination process of anhydrous indium(III) oxalate with carbon tetrachloride vapour in an argon stream was studied at different temperatures (200, 250, 300, 350, 400 and 450 °C) and times (5, 10, 15, 20 and 25 h) each. The reaction products were analysed by determination of indium and chlorine content aimed at their purity control. From the results obtained, a new simple method was developed for preparation of pure anhydrous indium(III) chloride.

From destructive CCl4 adsorption to grafting SO3H groups onto activated carbon fibers

Nanoporous activated carbon fibers (BusofitTM, BACF) showed effective adsorption of carbon tetrachloride (CTC) vapors. About 2.50 mmol × g−1 of chlorine, in the form of trichloromethyl and chlorine groups, can be grafted onto BACF surface by thermal decomposition of CTC at 450 °C. To obtain solid acids, this chlorinated BACF, the brominated and pristine BACFs, taken for comparison, were subjected to progressive sulfidation, hydrolysis and oxidation reactions for grafting sulfonic groups. By this wet route, sulfonic groups can substitute only 1.1–1.4 mmol × g−1 of the grafted chlorine groups. Nevertheless, solid acids obtained in this way have high catalytic performance in the 2-propanol dehydration to propene. For these catalysts, in the range from 180 to 220°C, a 100% alcohol conversion with 100% selectivity to propene could be reached. Thermoprogrammed desorption and thermal analysis revealed that the pyrolytic chlorination triggers the highest thermal stability of grafted sulfonic groups, and, they can repeatedly act in the dehydration reaction.

Sorbostriction of FAS-3 microporous carbon adsorbent upon vapor adsorption from a flow of nitrogen carrier gas

Sorbostriction (adsorption-induced deformation) of FAS-3 microporous carbon adsorbent is investigated under dynamic conditions upon adsorption of benzene, carbon tetrachloride, and n-hexane vapors from a flow of nitrogen carrier gas at 573 K. The values of maximum deformation and corresponding times depend on the amount of an adsorptive. The peak time of sorbostriction curves is different for each substance under study, which makes it possible to use the effect of wavelike sorbostriction for the development of sensors for the control of qualitative and quantitative compositions of gas mixtures.

Emission characteristics of pulse-periodic barrier-discharge plasma in a mixture of krypton with argon and liquid freon vapor

Radiation of a nanosecond barrier discharge in a mixture of krypton, argon, and carbon-tetrachloride vapor is studied in the spectral range of 150–300 nm. The plasma radiation spectra and the dependences of the intensities of the 258 nm Cl2(D′ → A′), 222 nm KrCl(B → X), and 175 nm ArCl(B → X) bands on the partial pressure of liquid freon vapor, argon, and krypton, as well as on the discharge excitation conditions, are studied. The optimal compositions of gas mixtures for creating a broadband UV-VUV emitter based on the band system of argon chloride, krypton chloride, and chlorine molecule are determined.

Analysis of Soil Vapor Extraction Data to Evaluate Mass‐Transfer Constraints and Estimate Source‐Zone Mass Flux

Methods are developed to use data collected during cyclic operation of soil vapor extraction (SVE) systems to help characterize the magnitudes and timescales of mass flux associated with vadose zone contaminant sources. Operational data collected at the Department of Energy's Hanford site are used to illustrate the use of such data. An analysis was conducted of carbon tetrachloride vapor concentrations collected during and between SVE operations. The objective of the analysis was to evaluate changes in concentrations measured during periods of operation and non-operation of SVE, with a focus on quantifying temporal dynamics of the vadose zone contaminant mass flux, and associated source strength. Three mass-flux terms, representing mass flux during the initial period of a SVE cycle, during the asymptotic period of a cycle, and during the rebound period, were calculated and compared. It was shown that it is possible to use the data to estimate time frames for effective operation of an SVE system if a sufficient set of historical cyclic operational data exists. This information could then be used to help evaluate changes in SVE operations, including system closure. The mass-flux data would also be useful for risk assessments of the impact of vadose-zone sources on groundwater contamination or vapor intrusion.

Chlorination methods applied to recover refractory metals from tin slags

Cassiterite, the principal ore of tin, contains a considerable amount of niobium and tantalum, which are rejected in the tin smelter slag. Therefore, the tin slag should be considered as an important source of niobium and tantalum, particularly when the reserves of the principal ores of these two metals, are very limited in nature. Because of the increasing demand and very high value of these two metals, it has been necessary to develop a suitable process to recover niobium and tantalum from tin smelting slag. In view of certain advantages of chloride metallurgy, the authors have carried out some studies on chlorination of tin slag by gaseous chlorine in presence of carbon, hydrochloric acid leaching and chlorination by carbon tetrachloride vapor, at a comparatively low temperature and partial pressure, to recover the metal values, particularly niobium and tantalum. In this paper, based on thermodynamics and kinetics of these chlorination processes, the recovery of Nb and Ta and some associated metals has been briefly described and discussed. Based on the findings of the chlorination studies made, some further investigations for recovering niobium and tantalum from tin slags have been suggested.

Abrogation of the Antifibrotic Effects of Natural Killer Cells/Interferon-γ Contributes to Alcohol Acceleration of Liver Fibrosis

Chronic alcohol drinking accelerates liver fibrosis in patients with viral hepatitis that cannot be fully explained by ethanol-enhanced liver damage. Here, we identified a novel mechanism by which alcohol accelerates liver fibrosis: inhibition of the antifibrotic effects of natural killer (NK) cells and interferon-gamma (IFN-gamma). Alcohol administration was achieved by feeding mice with a liquid diet containing 5% ethanol for 8 weeks. Liver fibrosis was induced by administration of carbon tetrachloride (CCl(4)) for 2 weeks. Hepatic stellate cells (HSCs) were also isolated and cultured for in vitro studies. CCl(4) treatment induced greater fibrosis and less apoptosis of HSCs in ethanol-fed mice compared with pair-fed mice. Polyinosinic-polycytidylic acid (Poly I:C) or IFN-gamma treatment inhibited liver fibrosis in pair-fed but not in ethanol-fed mice. Poly I:C activation of NK cell cytotoxicity against HSCs was attenuated in ethanol-fed mice compared with pair-fed mice, which was due to reduced natural killer group 2 member D (NKG2D), tumor necrosis factor-related apoptosis-inducing ligand, and IFN-gamma expression on NK cells from ethanol-fed mice. In vitro, HSCs from ethanol-fed mice were resistant to IFN-gamma-induced cell cycle arrest and apoptosis compared with pair-fed mice. Such resistance was due to diminished IFN-gamma activation of signal transducer and activator of transcription 1 (STAT1) in HSCs from ethanol-fed mice caused by the induction of suppressors of cytokine signaling proteins and the production of oxidative stress. Finally, HSCs from ethanol-fed mice were resistant to NK cell killing, which can be reversed by transforming growth factor-beta1 (TGF-beta1) neutralizing antibody. Chronic ethanol consumption attenuates the antifibrotic effects of NK/IFN-gamma/STAT1 in the liver, representing new and different therapeutic targets with which to treat alcoholic liver fibrosis.

Tribological Properties of Films Formed by the Reaction of Carbon Tetrachloride with Iron

The tribological properties of halide films grown on iron by reaction with carbon tetrachloride vapor at a temperature of 617 K and a pressure of 1.7 Torr are compared, in ultrahigh vacuum, with FeCl2 films evaporated onto the surface. It is found that the reactively formed film has a slightly lower limiting friction coefficient than the evaporated layer (~0.06 compared to ~0.08), which may be due either to the diffusion of some carbon into the substrate or the formation of a more oriented layer when this is formed reactively. The major difference between the reactively grown and evaporated film is that the evaporated layer attains the minimum friction when ~40 A of FeCl2 has been evaporated, while the reactively formed layer has a minimum friction coefficient when a film of 6±2 A has been deposited. In the case of the evaporated FeCl2 film, the growth of second and subsequent layers proceeds before the first layer is complete. It has been shown that the friction coefficient reaches its minimum value after completion of the first monolayer, a process that is complete after the evaporation of ~40 A of FeCl2. In the case of the film formed by reaction with CCl4, the halide film grows directly on the surface implying that the FeCl2 monolayer thickness is ~6 A. This value is in good agreement with the layer thickness in bulk ferrous chloride.

Kinetics of low-temperature chlorination of vanadium pentoxide by carbon tetrachloride vapor

Low-temperature chlorination of vanadium pentoxide by carbon tetrachloride vapor in dilution with nitrogen has been carried out. The effect of time, particle size, partial pressure of CCl4 vapor (0.1 to 0.6 atm), and temperature (553 to 788 K) on the extent of chlorination of V2O5 has been investigated. The extent of chlorination of the oxide is found to increase with a decrease in its particle size. In all cases, the reaction followed a topochemical reaction model, obeying the following relationship: $$1 - (1 - \alpha )^{{1 \mathord{\left/ {\vphantom {1 3}} \right. \kern-\nulldelimiterspace} 3}} = kt$$ where α is the fraction of V2O5 chlorinated in time t and k is the rate constant. The rate constant has been found to be directly proportional to the partial pressure of CCl4 (PCCl4). The activation energy values between 553 and 643 K and that between 683 and 788 K have been calculated and found to be 38.9 and 11.5 kJ/mole, respectively. Based on the kinetics results, mechanisms of reaction in the two temperature ranges have been suggested. It has been possible to chlorinate V2O5 at 753 K to about 87 pct in 30 minutes, using a very low partial pressure of CCl4 of 0.15 atm.

Linearization of calibration curves by aerosol carrier effect of CCl 4 vapor in electrothermal vaporization inductively coupled plasma mass spectrometry

Carbon tetrachloride vapor as gaseous phase modifier in a graphite furnace electrothermal vaporizer (GFETV) converts heavy volatile analyte forms to volatile and medium volatile chlorides and produces aerosol carrier effect, the latter being a less generally recognized benefit. However, the possible increase of polyatomic interferences in inductively coupled plasma mass spectrometry (GFETV–ICP-MS) by chlorine and carbon containing species due to CCl 4 vapor introduction has been discouraging with the use of low resolution, quadrupole type MS equipment. Being aware of this possible handicap, it was aimed at to investigate the feasibility of the use of this halogenating agent in ICP-MS with regard of possible hazards to the instrument, and also to explore the advantages under these specific conditions. With sample gas flow (inner gas flow) rate not higher than 900 ml min −1 Ar in the torch and 3 ml min −1 CCl 4 vapor flow rate in the furnace, the long-term stability of the instrument was ensured and the following benefits by the halocarbon were observed. The non-linearity error (defined in the text) of the calibration curves (signal versus mass functions) with matrix-free solution standards was 30–70% without, and 1–5% with CCl 4 vapor introduction, respectively, at 1 ng mass of Cu, Fe, Mn and Pb analytes. The sensitivity for these elements increased by 2–4-fold with chlorination, while the relative standard deviation (RSD) was essentially the same (2–5%) for the two cases in comparison. A vaporization temperature of 2650 °C was required for Cr in Ar atmosphere, while 2200 °C was sufficient in Ar + CCl 4 atmosphere to attain complete vaporization. Improvements in linear response and sensitivity were the highest for this least volatile element. The pyrolytic graphite layer inside the graphite tube was protected by the halocarbon, and tube life time was further increased by using traces of hydrocarbon vapor in the external sheath gas of the graphite furnace. Details of the modification of the gas supply for HGA-600MS furnace and the design of the volatilization device are described.

P-Type Carbon Nitride Synthesized by a Gas-Solid Reaction

Amorphous carbon nitride with high nitrogen content (N/C = 1.14) was first successfully synthesized via a novel gas-solid reaction between carbon tetrachloride (CCl4) vapor and melamine (C3N6H6) at 600°C under atmospheric pressure. The product has been characterized by X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, X-ray powder diffraction, and simultaneous thermogravimetry-differential scanning calorimetry. It was revealed that the carbon nitride is sp3-dominated and the reaction-driven sp2 to sp3 transformation in the material was proposed. The electrical properties of the material were also investigated, showing high p-type conductivity.

Electrical and Optical Properties of Carbon-Doped GaN Grown by MBE on MOCVD GaN Templates Using a CCl4 Dopant Source

AbstractCarbon-doped GaN was grown by plasma-assisted molecular-beam epitaxy using carbon tetrachloride vapor as the dopant source. For moderate doping mainly acceptors were formed, yielding semi-insulating GaN. However at higher concentrations p-type conductivity was not observed, and heavily doped films (<5×1020 cm-3) were actually ntype rather than semi-insulating. Photoluminescence measurements showed two broad luminescence bands centered at 2.2 and 2.9 eV. The intensity of both bands increased with carbon content, but the 2.2 eV band dominated in n-type samples. Intense, narrow (∼6 meV) donor-bound exciton peaks were observed in the semi-insulating samples.

Studies on the kinetics of carbon tetrachloride chlorination of tantalum pentoxide

Studies on the kinetics of chlorination of tantalum pentoxide powder by carbon tetrachloride vapor in dilution with nitrogen have been carried out by weight-loss measurements in two temperature ranges, i.e., 698 to 773 K and 793 to 853 K. The effect of time, temperature, and partial pressure of CCl4\((P_{CCl_4 } )\) on the kinetics of chlorination of the powder Ta2O5, (−105+74 µm) has been investigated. In both the temperature ranges, the chlorination results have been found to fit the following relationship during the “initial periods:” $$ - \ln (1 - \alpha ) = k_1 t$$ where α is the fraction of the oxide reacted in time t and k1 is the rate constant. In the low- and high-temperature ranges, the activation-energy (E) values have been calculated and were found to be 145 and 71 kJ/mole, respectively. The k1 value was found to be proportional to PCCl41.5 in the lower-temperature range, while in the higher-temperature range, it was found to be proportional to PCCl40.9.

The electronic nature of the Cl adatom at GaAs(1 1 0) surfaces due to Cl 2 dissociative adsorption and CCl 4 photodecomposition

Clean, well defined GaAs(1 1 0) surfaces at room temperature, were exposed to carbon tetrachloride vapor. Only when illuminated during the exposure (with 400 mW/cm 2 of 532 nm light) could adsorbed species be observed with scanning tunneling microscopy (STM) on flat terraces. The features in the STM images were compared to those due to exposure to Cl 2 gas in the dark, and the CCl 4 decomposition products were shown to be identical to chlorine adatoms which are bound to surface Ga atoms (A-type). Since the Cl adatoms appear dark at low positive sample bias, and bright at high bias, and from the absence of localized contrast in atomically-resolved surface photovoltage images, we deduce that the Cl adatom interacts with the Ga-induced C 3 surface resonance, that it (or the Cl–Ga complex) is not charged, and it does not give rise to any surface state in the GaAs band gap that could pin the Fermi level.

Influence of intestinal flora on the development of fibrosis and cirrhosis in a rat model1

The gut flora play a significant role in the disposition of many foreign substances, as well as producing nutrients and toxins that may be absorbed and reach the liver. This study examines the influence of antibiotic-induced alterations in gut flora on the development of hepatic fibrosis in a rat model. Thirty-six male Porton rats were fed alcohol (3.9 g/kg per day) in the drinking water and exposed to carbon tetrachloride (CCl4) vapor (80 p.p.m.) for 6 h each night, five nights per week. Half were also given neomycin (330 mg/kg per day) and polymyxin B (105 mg/kg per day) in the drinking water. Fecal cultures were carried out at 0, 3, 8 and 13 weeks; rats were killed at 14 weeks. Coded liver section were assessed for fibrosis using a graded scale (0, no abnormal fibrosis to 4, early or established cirrhosis). Rats that received antibiotics had significantly higher fibrosis scores than those that did not (mean score 2.4 vs 1.4, P < 0.01, ordinal logistic regression). Three rats, all of which were in the antibiotic group, were cirrhotic. Rats that had received antibiotics fell into three groups. Four had overgrowth of Proteus mirabilis; in these the fibrosis scores (mean 1.5) were similar to those in the rats that did not receive antibiotic. In six, no organisms could be cultured; fibrosis scores of these (mean 2.3) were slightly elevated (P = 0.03), but this was mainly because of a single rat in this subgroup being cirrhotic. The remaining eight had overgrowth of Morganella morganii; these had significantly (P < 0.001) elevated fibrosis scores. Furthermore, in this subgroup, fibrosis scores were significantly correlated (Spearman's r = 0.82, P = 0.01) with the number of weeks of Morganella colonization. Antibiotic treatment exacerbated fibrosis in the alcohol/CCl4 rat model; this effect appeared to be related to the type of gut flora and may be endotoxin-mediated.