Adsorption Of Carbon Tetrachloride Research Articles

Sorptive Deformation of Porous Sorbents

Deformations of granulated recuperative activated carbon AR-V (produced in granulated form from coal dust (coals mixture) and adhesion agents by steam treatment at the temperature of 1100 — 1200K) upon carbon tetrachloride adsorption has been studied. To solve this problem a dilatometer was used. Its main part was a line differential transformer, the core of which was connected to the adsorbent by means of a rod. Any changes in the adsorbent height caused a change in the core position in the transformer, which influenced the signal recorded from its secondary winding. These results were compared with the adsorption isotherms.Also deformations of cation – substituted vermiculite (Na form) upon water vapor sorption have been studied. The sorbent used was plate – formed, anisotropic, and swelled only in the direction perpendicular to the plane of the plates. The results obtained were compared with the sorption, calorimetry (a Calvet – type microcalorimeter with a microbalance attachment was used) and X-ray data. High sensitivity of the dilatometric method to the structural changes of the laminated silicates whose cell structures expand upon hydration has been shown. The dilatometer used allowed the measurement of absolute deformations in the range 1(10-7 to 3(10-3 m.

A re-assessment of the isosteric heat for CCl4 adsorption on graphite

We have carried out molecular simulations of carbon tetrachloride adsorption on graphite, in order to investigate the role of the octopole in potential models for the CCl4/graphite system, and the temperature dependence of the first-order gas-liquid transition in the first adsorbate layer. Two classes of potential model for carbon tetrachloride were considered: the first has 5 LJ sites and the second includes five partial charges to model the leading octopole. Both models are adequate to represent the vapour-liquid equilibrium, suggesting that the octopole makes an insignificant contribution to the properties of the bulk phase. Both models show that adsorbed CCl4 molecules are delocalized on a graphite surface because of the strong intermolecular interactions. It is found that the LJ sites on the chlorine atoms, not the octopole, play the most important role in matching the experimental isotherm and isosteric heat data with simulation. The heat is constant, across the first-order transition of the first adsorbate layer. The simulation results show that both the magnitude of the density jump, and the isosteric heat across the first-order transition, decrease as the temperature increases. This is in qualitative agreement with the 1972 experimental data of Avgul and Kiselev, but these experimental data exhibit an unusually strong decrease in the isosteric heat, and the coexistence region between the two phases displays an unusual asymmetrical shape. Detailed analysis of our simulation results, together with the calculated isosteric heat from the experimental isotherms of Machin and Ross, show that there may be errors associated with the heat data of Avgul and Kiselev at high temperatures.

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.

树叶提取液制备纳米零价铁及处理含四氯化碳废水的研究

利用紫叶小檗树叶提取液绿色制备的纳米零价铁。采用正交试验探究紫叶小檗树叶提取液最佳提取条件，结果表明，提取因素的重要性依次为浸提温度 > 固液比 > 浸提时间 > 乙醇浓度。最佳试验组合为浸提温度50℃、乙醇和树叶的液固比为60:1 mL/g、浸提时间为30 min、乙醇浓度为40%。采用XRD、SEM、TEM及FT-IR对紫叶小檗树叶提取液和合成的纳米零价铁进行了分析表征。以四氯化碳废水为目标吸附物，检测合成的纳米零价铁对四氯化碳的吸附还原性能。考察了初始浓度、pH和投加量对吸附还原性能的影响。结果表明：当pH和投加量一定时，初始浓度为4 mg/L时，反应时间110 min时，合成的纳米零价铁对四氯化碳的降解率最高为98.19%。当四氯化碳初始浓度和零价铁的投加量不变的条件下，pH = 6.1，反应110 min时，降解率为99.6%。当四氯化碳初始浓度和pH一定时，投加量为0.12 g/L，降解率为97.89%。该还原反应符合一级反应动力学模型。 Nano zero-valent iron was synthesized by green methods based on purple leaf barberry leaves extract as a reducing agent and stabilizer. In order to explore the best extraction conditions of the purple leaf barberry leaves extract, we used orthogonal test. The results showed that the contributions of the factors to the polyphenols extracting could be list in descending order as follows: extraction temperature > solid-liquid ratio > extraction time > ethanol concentration. In addition, the best extracting conditions were temperature of 50˚C, ethanol and liquid solid ratio of leaves was 60:1 ml/g and leaching time was 30 min and ethanol concentration was 40%. Purple leaf barberry leaves extract and synthesis nano zero valent iron were analyzed and characterized by XRD, SEM, TEM and FTIR. Green synthesis of nano zero-valent iron adsorption performance was detected, by aiming at carbon tetrachloride adsorption. The influences of adsorption performance by the initial concentration, pH and dosing quantity were investigated. The result show that under the constant as pH and additive quantity, initial concentration of 4 mg/L, 110 min degradation reaction rate effect was 98.19%. When the initial concentration of carbon tetrachloride and zero-valent iron dosing quantity invariable condition, the optimum condition for pH is 6.1, the reaction of 110 min, the degradation rate was 99.6%. When carbon tetrachloride under the constant initial concentration and pH, the best dosing quantity is 0.12 g/L, the degradation rate is 97.89%. This reduction reaction is in line with the first order reaction kinetics model.

Adsorption of Aqueous Carbon Tetrachloride by a Novel TCAS-Loaded Resin

Through the method of the static tests, the removal rate of aqueous carbon tetrachloride onto a new TCAS-loaded resin was researched. This TCAS-loaded resin was made of a novel supramolecular acceptor compound named thiacalix [arenetetrasulfonate (TCAS) and anion exchange resin, and the adsorption mechanism was discussed preliminarily. The results of adsorption indicated that the pH value was an important factor for the removal of carbon tetrachloride and it would be better for the adsorption if the pH value was greater than 6. The operating temperature should be controlled in 5 to 15°C for the adsorption of carbon tetrachloride onto TCAS-loaded resin while the removal rate decreased with the temperature increasing and the best time for reaction was 40min. The removal rate of carbon tetrachloride in aqueous solution was better when 25mL aqueous solution of carbon tetrachloride (1.0mg/L) was adsorbed by 0.5g TCAS-loaded resin. The carbon tetrachloride can be resolving and TCAS-loaded resin can be reused.

Oxidation of magnesium with carbon tetrachloride in aprotic solvents

Formal kinetic regularities and the end products of oxidation of magnesium with carbon tetrachloride in the environment of dipolar aprotic solvents were revealed. The effective equilibrium constant, enthalpy and entropy of adsorption of carbon tetrachloride and N,N-dimethylformamide at a metal surface, the rate constant and activation energy of the investigated reaction were determined. The effect of temperature on the dependence of the process on the donor properties of the used coordinating solvents was established and justified. A probable scheme of the process was suggested.

Synthesis and characterization of mesoporous carbon with narrow pore size distribution derived from rare earth–macromolecule complexes

AbstractMesoporous carbon with narrow pore size distribution was novelly derived from rare earth–macromolecule complexes, which were formed by the coordination between grafted novolac‐type phenolic resin and rare earth ions (Ce3+). The as‐made resins or carbons were characterized by infrared spectrum, thermogravimetry, carbon tetrachloride adsorption, nitrogen adsorption, and scanning electron microscope. The results showed that the rare earth–macromolecule complexes were formed successfully, which could promote the dispersion of rare earth elements in the precursor and further control the pore structure and pore size distribution of as‐made mesoporous carbon during steam‐activation process. The as‐made mesoporous carbon exhibited typical mesoporous structure and relatively narrow pore size distribution, and the mesoporosity of it was up to 88%. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Effect of air humidity on the removal of carbon tetrachloride from air using Cu–BTC metal–organic framework

We have used interatomic potential-based simulations to study the removal of carbon tetrachloride from air at 298 K, using Cu-BTC metal organic framework. We have developed new sets of Lennard-Jones parameters that accurately describe the vapour-liquid equilibrium curves of carbon tetrachloride and the main components from air (oxygen, nitrogen, and argon). Using these parameters we performed Monte Carlo simulations for the following systems: (a) single component adsorption of carbon tetrachloride, oxygen, nitrogen, and argon molecules, (b) binary Ar/CCl(4), O(2)/CCl(4), and N(2)/CCl(4) mixtures with bulk gas compositions 99 : 1 and 99.9 : 0.1, (c) ternary O(2)/N(2)/Ar mixtures with both, equimolar and 21 : 78 : 1 bulk gas composition, (d) quaternary mixture formed by 0.1% of CCl(4) pollutant, 20.979% O(2), 77.922% N(2), and 0.999% Ar, and (e) five-component mixtures corresponding to 0.1% of CCl(4) pollutant in air with relative humidity ranging from 0 to 100%. The carbon tetrachloride adsorption selectivity and the self-diffusivity and preferential sitting of the different molecules in the structure are studied for all the systems.

The system of carbon tetrachloride and closed carbon nanotubes analyzed by a combination of molecular simulations, analytical modeling, and adsorption calorimetry

Using the combined techniques of molecular simulation, simple analytical modeling, and adsorption calorimetry, we propose new models describing adsorption onto closed carbon nanotubes. The models are capable of describing the adsorption isotherms and calorimetric enthalpy of carbon tetrachloride adsorption measured on three different closed carbon nanotubes. It is shown that the assumption of the presence of two types of surface centers (high- and low-energy centers) on external tube surfaces is sufficient to describe experimental adsorption and calorimetric enthalpy data.

Photoemission study of CCl 4 adsorption on Si(1 1 1)-7 × 7

Adsorption of carbon tetrachloride (CCl 4) on Si(1 1 1)-7 × 7 at room temperature (RT) and low temperature (LT) was investigated by X-ray photoelectron spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS). It was demonstrated that at RT CCl 4 dissociates on the Si(1 1 1)-7 × 7 surface leaving the surface extensively adsorbed with atomic Cl species. The dissociated Cl shows site preference to Si restatoms resulting in quick extinction of dangling bonds at the Si restatoms. At LT (around 120 K), both molecular and dissociative adsorption of CCl 4 occurs, which produces Cl, CCl x ( x ⩽ 3), and CCl 4 on the surface. The dangling bonds at the restatoms and adatoms were simultaneously quenched upon the LT CCl 4 adsorption. The site selectivity of restatoms to adatoms for molecule adsorption on the Si(1 1 1)-7 × 7 surface is discussed.

Synthesis of linear alkylbenzene sulphonate intercalated iron(II) iron(III) hydroxide sulphate (green rust) and adsorption of carbon tetrachloride

AbstractGreen rusts, GRs, can act as both sorbents and reductants towards selected pollutants. Organo-GRs are expected to combine these properties with a high affinity for hydrophobic substances. A novel organo-GR, GRLAS, was synthesized by incorporating a mixture of linear alkylbenzenesulphonates (LAS) into the interlayer space of synthetic sulphate green rust, GRSO4 . Mössbauer analysis of GRLAS indicates that the structure of the organo-GR is very similar to that of the initial GRSO4 with regard to the FeII/FeIII ratio and local coordination of Fe atoms. X-ray diffraction demonstrates that the GRLAS formed was well ordered, although a mixture of surfactant was used for intercalation. The basal spacings of the GRLAS and the kinetics of the ion-exchange process were dependent on the initial surfactant loading; basal spacings of ~2.85 nm were obtained at LAS solution concentrations >10 mM. The ratio LASadsorbed/SO42–desorbed significantly exceeded the stoichiometric ratio of 2 during the initial part of the ion-exchange process (t = 5 h). However, this ratio was reached progressively with time. GRSO4 preferentially sorbed LAS homologues with long alkyl chains over short ones. Carbon tetrachloride was successfully adsorbed into GRLAS. The adsorption isotherm was linear with a distribution coefficient, Kd, of 505±19 litre kg–1.

Gaseous adsorption of carbon tetrachloride onto carbon nanofiber arrays prepared by template-assisted synthesis

Adsorption of carbon tetrachloride onto aligned carbon nanofiber (CNF) arrays, prepared by a template-assisted synthesis, in vapor phase is conducted in the present study. Porous structure analysis indicated that various pore size distributions of the CNF arrays are found to vary with their tubular sizes. The increasing tubular size is accompanied by a decreasing micropore fraction as well as a vapor-phase adsorption capacity. Freundlich and Dubinin–Radushkevich models were employed to analyze the equilibrium adsorption data. The surface accessibility of CNF arrays, i.e., adsorption capacity per surface area, was found to decrease with the pore size, according to these models. It is suggested on the basis of the present work that the micropore fraction of CNFs plays an important role in determining the adsorption coverage. Both the equilibrium constant and free energy for the vapor-phase adsorption increase with the micropore proportion, indicating that the micropores act as a high-energy site for adsorption of carbon tetrachloride.

Adsorptive Surface Coverage of Carbon Tetrachloride onto Carbon Nanofibers Array

This work explores an estimation of adsorptive surface coverage for carbon tetrachloride onto different carbon nanofibers (CNFs). Two kinds of CNFs with various pore characteristics are fabricated by template-based and thermal chemical vapor deposition methods, respectively. The pore size distributions of these carbons, determined according to the density functional theory model, are found to vary with synthesis methods. The results of adsorption experiments show that CCl4 adsorption isotherms of these CNFs are of Langmuir-type model during the restricted pressure of 0–0.2 atm at 30°C. The surface coverage capable of adsorbing CCl4 molecules onto the CNFs can be determined based on the monolayer adsorption model. Interestingly, the CCl4 capacity of these CNFs does not proportionally increase with their specific surface area, and the CNFs with more micropore fraction facilitate the adsorptive surface coverage. This finding attributes to a fact that micropores in the CNFs have stronger adsorption energies, thus, become a major provider for carbon tetrachloride adsorption.

Surface chemistry of polyacrylonitrile- and rayon-based activated carbon fibers after post-heat treatment

Polyacrylonitrile- and rayon-based activated carbon fibers (ACFs) subject to heat treatment were investigated by means of elemental analyzer, and X-ray photoelectron spectroscopy (XPS). The total ash content of all ACFs was also analyzed. The adsorption of benzene, carbon tetrachloride and water vapor on ACFs was determined to shed light on the role of surface chemistry on gas adsorption. Results show that different precursors resulted in various elemental compositions and imposed diverse influence upon surface functionalities after heat treatment. The surface of heat-treated ACFs became more graphitic and hydrophobic. Three distinct peaks due to C, N, and O atoms were identified by XPS, and the high-resolution revealed the existence of several surface functionalities. The presence of nitride-like species, aromatic N-imines, or chemisorbed nitrogen oxides was found to be of great advantage to adsorption of water vapor or benzene, but the pyridine-N was not. Unstable complexes on the surface would hinder the fibers from adsorption of carbon tetrachloride. The rise in total ash content or hydrogen composition was of benefit to the access of water vapor. Modifications of ACFs by heat treatment have effectively improved adsorption performance.

Adsorption of Carbon Tetrachloride on Graphitized Thermal Carbon Black and in Slit Graphitic Pores: Five-Site versus One-Site Potential Models

The performance of intermolecular potential models on the adsorption of carbon tetrachloride on graphitized thermal carbon black at various temperatures is investigated. This is made possible with the extensive experimental data of Machin and Ross(1), Avgul et al.,(2) and Pierce(3) that cover a wide range of temperatures. The description of all experimental data is only possible with the allowance for the surface mediation. If this were ignored, the grand canonical Monte Carlo (GCMC) simulation results would predict a two-dimensional (2D) transition even at high temperatures, while experimental data shows gradual change in adsorption density with pressure. In general, we find that the intermolecular interaction has to be reduced by 4% whenever particles are within the first layer close to the surface. We also find that this degree of surface mediation is independent of temperature. To understand the packing of carbon tetrachloride in slit pores, we compared the performance of the potential models that model carbon tetrachloride as either five interaction sites or one site. It was found that the five-site model performs better and describes the imperfect packing in small pores better. This is so because most of the strength of fluid-fluid interaction between two carbon tetrachloride molecules comes from the interactions among chlorine atoms. Methane, although having tetrahedral shape as carbon tetrachloride, can be effectively modeled as a pseudospherical particle because most of the interactions come from carbon-carbon interaction and hydrogen negligibly contributes to this.

Destructive adsorption of carbon tetrachloride on nanometer titanium dioxide

The reaction between nanometer TiO2 and CCl4 in the presence of oxygen has been studied in order to investigate the potential of nanometer TiO2 as a destructive reagent for chlorinated hydrocarbons. Two kinds of nanometer TiO2 of different size were synthesized. The properties of the destructive adsorption of CCl4 over nanometer TiO2 of about 40 nm in size were compared with that over nanometer TiO2 of about 80 nm in size. The reactivity toward CCl4 of nanometer TiO2 of about 40 nm in size was remarkably higher than that of nanometer TiO2 of about 80 nm in size. The products produced included CO2, COCl2, Cl2, titanium oxychloride, TiCl4, carbon, CO and HCl. HCl was a major gaseous product. Hydrogen of HCl came from traces of water in the carrier gas and surface OH groups of TiO2. The formation of TiCl4 made the interaction surface renew so that CCl4 could further interact with the bulk of the particles. TiO2 was regenerated through the exchange of chlorine with oxygen at 550°C in the carrier gas so that larger quantities of CCl4 are decomposed over nanometer TiO2 in the presence of oxygen. A mechanism has been proposed for the destructive adsorption and desorption of CCl4 over nanometer TiO2 in the presence of oxygen.

Physical adsorption of carbon tetrachloride on as-produced and on mechanically opened single walled carbon nanotubes

Adsorption properties of carbon tetrachloride (CCl 4) on single walled carbon nanotubes (SWNTs) before and after mechanical cutting were investigated by adsorption volumetry between 224 and 232 K. Physical adsorption of CCl 4 on the outer surface of bundles, in the grooves and inside opened tubes is discussed in the light of the results obtained under similar conditions for krypton and xenon. The amount adsorbed both in grooves and inside the opened tubes has been estimated as well as the CCl 4 isosteric heat of adsorption on the convex external walls.

Adsorption of Carbon Tetrachloride and Chloroform on Activated Carbon at (300.15, 310.15, 320.15, and 330.15) K

The adsorption equilibria for carbon tetrachloride and chloroform vapors on activated carbon (Sorbonorit B4) were measured using a gravimetric method. The equilibrium data were obtained at (300.15, 310.15, 320.15, and 330.15) K with the pressure up to 7 kPa for carbon tetrachloride and 4.9 kPa for chloroform, respectively. The Toth and Dubinin-Astakov equations were successful in correlating the experimental isotherms. The Toth equation was used to determine thermodynamic properties such as the isosteric enthalpy of adsorption and Henry's constant. By using the Dubinin-Astakov isotherm equation, the total micropore volume of the adsorbent was determined

Comparison of phosgene formation from adsorption of carbon tetrachloride on oxygen modified Ir(111) and oxygen modified Ir(110)

The production of phosgene was observed when a pure carbon tetrachloride molecular beam was impinged on the oxygen modified Ir (111) and Ir(110) surfaces. Although the mechanism of phosgene formation is believed to be identical on the two surfaces, important differences in reactivity were observed. The phosgene production of oxygen modified Ir(111) was greater than the oxygen modified Ir(110) surface. Oxygen atoms are more tightly bound to the Ir(110) surface making it less reactive for the production of phosgene. Formation of the surface oxide on Ir(110) (which begins to occur if the surface is heated above 550 K) reduces adsorption of carbon tetrachloride, which necessarily decreases phosgene formation. The Ir(110) surface may also cause a more rapid decomposition of the adsorbed CCl2 intermediate. Phosgene production on oxygen modified Ir(110) also demonstrated a maximum at 500 K, whereas phosgene production on oxygen modified Ir(111) decreased with increasing temperature.

Phosgene formation from adsorption of carbon tetrachloride on oxygen modified Ir(111)

The production of phosgene was observed when a pure carbon tetrachloride molecular beam was impinged on an oxygen modified Ir(111) surface. We propose a mechanism involving the partial surface decomposition of the CCl 4 molecule to CCl 2 which subsequently reacts with adsorbed oxygen to form phosgene. Phosgene formation was maximized at an oxygen surface coverage of approximately 0.3 ML. Increasing the surface temperature resulted in a decrease in formation of COCl 2, as competing reactions became important, especially the rapid and more complete decomposition of CCl 4 on the surface prior to reaction with oxygen.