Vapor-phase adsorption of a mixture of benzene and chlorobenzene on the carbon adsorbent obtained by pyrolysis of hypercrosslinked polystyrene

Adsorption of a mixture of benzene and chlorobenzene from the gas phase on the carbon adsorbent D4609 (Purolite Int.) obtained by the pyrolysis of hypercrosslinked polystyrene was studied. The adsorption of the binary vapor mixture is satisfactorily described in terms of the theory of ideal adsorption solution. Specific features of the adsorption behavior of mixtures on this adsorbent are discussed.     

The thermodynamics of benzene adsorption on carbon obtained by the pyrolysis of hypercrosslinked polystyrene

The Glukauf chromatography method was used to study the adsorption of benzene on a microporous carbon material prepared by the pyrolysis of hypercrosslinked polystyrene. The thermodynamic characteristics of adsorption were determined as functions of the degree of pore filling. Over the range of relative pressures studied (<0.005), adsorption was shown to occur in ultramicropores by the mechanism of primary filling without condensed phase formation. Original Russian Text ? L.D. Asnin, V.A. Davankov, A.V. Pastukhov, K. Kaczmarski, 2009, published in Zhurnal Fizicheskoi Khimii, 2009, Vol. 83, No. 7, pp. 1356–1359.     

Adsorption of hexane, cyclohexane, and benzene on microporous carbon obtained by pyrolysis of hypercrosslinked polystyrene

The relationships of adsorption of hexane, cyclohexane, and benzene on a D4609 microporous carbon adsorbent obtained by the pyrolysis of hypercrosslinked polystyrene are compared. It is shown that in the range of relative pressures corresponding to the filling of ultramicropores, the adsorption behaviors of cyclohexane and benzene are essentially identical, in contrast to hexane, which is characterized by higher adsorption values and isosteric heat of adsorption. The observed relationships are explained by the steric features of the distribution of molecules of various structures in ultramicropores.     

Description of adsorption equilibrium of PAHs on hypercrosslinked polymeric adsorbent using Polanyi potential theory

In this research,static adsorption of three polycyclic aromatic hydrocarbons(PAHs),naphthalene,acenaphthene,and fluorene,from aqueous solutions onto hypercrosslinked polymeric adsorbent within the temperature range of 288-308 K is investigated.Several isotherm equations are correlated with the equilibrium data,and the experimental data is found to fit the Polanyi-Dubinin-Manes model best within the entire range of concentrations,providing evidence that pore-filling is the dominating sorption mechanism for PAHs.The study shows that the molecular size of adsorbates has distinct in-fluence on adsorption capacity of hypercrosslinked polymeric adsorbent for the PAHs;the larger the adsorbate molecular size,the lower the adsorption equilibrium capacity.Based on the Polanyi-Dubinin-Manes model,the molecular size of adsorbates was introduced to adjust the adsorbate molar volume.Plots of qv vs.(σε /Vs) are collapsed to a single correlation curve for different adsorbates on hypercrosslinked polymeric resin.     

The adsorption of organic compounds on a modified carbon adsorbent Carbopack B

The thermodynamic characteristics of adsorption of several organic compounds on the carbon adsorbent Carbopack B before and after its modification by a monomolecular layer of cholesteryl-n-pentyl oxybenzoate were determined by gas chromatography. The initial adsorbent was close in its properties to graphitized carbon black. Modification weakened adsorbate-adsorbent attraction and increased the mobility of adsorbed molecules, to a greater extent for nonpolar adsorbents and to a lesser extent for compounds capable of specifically interacting with modifier molecules.     

Methane adsorption on AUK microporous carbon adsorbent

The isotherms of absolute methane adsorption on AUK microporous carbon adsorbent are measured at pressures of 1 Pa–6 MPa and temperatures of 177.65–393 K. The pattern of the isotherms remains unchanged when passing through the critical temperature of methane (T _cr = 190.77 K) and, as the temperature is elevated, the isotherms are shifted toward higher pressures in an almost symbate manner. Isosteres plotted for methane adsorption on AUK microporous carbon adsorbent within the same pressure and temperature ranges are adequately approximated by straight lines, with their slopes remaining unchanged when passing into the region of supercritical temperatures under the conditions of a pronounced imperfection of the gas phase. The Henry constant is determined for the system under consideration. It is shown that the Henry constants have close magnitudes for different methane-carbon adsorbent systems.     

Carbon dioxide adsorption on the microporous ACC carbon adsorbent

Adsorption isotherms of carbon dioxide on the microporous ACC carbon adsorbent and the adsorption deformation of the adsorbent were measured. The heats of adsorption at temperatures raising from 243 to 393 K and pressures from 1 to 5⋅10⁶ Pa were measured. In the low-temperature region (243 K), an increase in the amount adsorbed is accompanied by adsorbent contraction, and at high micropore fillings (a > 10 mmol g⁻¹) the ACC carbon adsorbent expands. At high temperatures, adsorbent expansion is observed in the whole region of micropore filling. At 243 K in the low filling region (a < 1 mmol g⁻¹), the heat of adsorption decreases smoothly from 27 to 24 kJ mol⁻¹. The heat of adsorption remains virtually unchanged in the interval 2 mmol g⁻¹ < a < 11 mmol g⁻¹ and then decreases to 8 kJ mol⁻¹ at a = 12 mmol g⁻¹. Taking into account the nonideal character of the gas phase and adsorbent deformation the heats of adsorption are strongly temperature-dependent in a region of high pressures. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1331–1335, June, 2005.     

Thermodynamics of methane adsorption on the microporous carbon adsorbent ACC

The behavior of the thermodynamic functions (differential molar isosteric heat of adsorption, entropy, enthalpy, and heat capacity) of the adsorption system methane—microporous carbon adsorbent ACC was analyzed at different adsorption equilibrium parameters in the temperature interval from 177.65 to 393 K and in the pressure range from 1 Pa to 6 MPa. The influence of the nonideal character of the gas phase and noninertness of the adsorbent were taken into account, which resulted in the appearance of the temperature dependence of the isosteric heat of adsorption, especially in the region of high pressures of the adsorptive. For the system studied, nonideality of the gas phase exerts the main effect on the thermodynamic functions of the adsorption system. In this interval of the parameters of the adsorption system, the correction to the noninertness of the adsorbent is not higher than 2.5%. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1765–1771, September, 2008.     

Kinetics of the sorption of triterpene saponin by hypercrosslinked polystyrene

The kinetics of sorption of triterpene saponin by the polymer sorbent NM-200 is considered. The influence of the surface activity of glycoside on the rate of formation and structure of the adsorption layer on the sorbent’s surface is established. The rate-determining step of sorption is found to be diffusion into the sorbent grain. The value of the activation energy demonstrates the determining role of dispersion forces in the interaction between triterpene saponin and the polymer sorbent MN-200.     

Deformation of AUK microporous carbon adsorbent induced by methane adsorption

The dependence of the relative linear deformation of AUK microporous carbon adsorbent on pressure is studied upon the adsorption of methane in the pressure range of 1 Pa to 6 MPa at 177.65, 216.2, 243.3, 273.15, 313, 333, and 393 K. It is found that the curves of adsorption-induced deformation show similar behavior; except for in the initial pressure range (p < 0.2 MPa), the adsorption-induced deformation increases with pressure and drops as the temperature rises. At low temperatures, a shrinkage region is observed in the initial part of the deformation curves that narrows with a rise in temperature. At temperatures above 350 K, the initial shrinkage is absent and the adsorbent expands with an increase in methane pressure. In the pressure and temperature ranges under investigation, the contribution of deformation to the differential isosteric heat of adsorption of AUK carbon adsorbent does not exceed 2%. It is shown that, upon the adsorption of CO₂, N₂, Ar, and CH₄ at 273 K and pressures below 6 MPa, the maximum deformation of AUK adsorbent varies cymbately with variations in the Lennard-Jones (6–12) potential constants for the pair interaction of gas molecules.     

Chromatographic behavior of benzimidazole derivatives on hypercrosslinked polystyrene by reverse-phase HPLC

Abstract

An important part in the research of separation of various compound classes is the study of relationship between structure and property by describing the effect of structure on compounds’ chromatographic retention. The aim of this work was to study the chromatographic retention of the firstly synthesized benzimidazoles from water-acetonitrile and water-methanol solutions on hypercrosslinked polystyrene (HCP) by high-performance liquid chromatography (HPLC). The effect of water-methanol and water-acetonitrile solutions’ composition on the benzimidazole derivative retention factors on HCP was studied. The thermodynamic characteristics of sorption of benzimidazoles’ transition from water-organic solutions onto the surface of HCP phase were obtained. The thermodynamic compensation effects were studied. It has been shown that the benzimidazole nitro derivative realizes additional specific interactions with the aromatic network of HCP. The slope ratio of the Soczewiński–Wachtmeister equation was calculated. It was shown that 1-hydroxymethylbenzimidazole and 2-aminobenzimidazole characterized by small volumes and containing hydrophilic substituents do not subordinate Soczewiński–Wachtmeister model under ranging from 75 to 85% concentrations of acetonitrile.     

Sorption of caffeine and theophylline on hypercrosslinked polystyrene

The sorption of caffeine and theophylline from water solutions on hypercrosslinked polystyrene MN-200 was studied. It is shown that sorption is described by the Langmuir equation. The conditions of the dynamic sorption concentration of caffeine and theophylline on a concentrating column and the conditions of its desorption were found. A procedure for spectrophotometric determination of caffeine and theophylline with a dynamic preconcentration is proposed.     

Ethane adsorption on microporous carbon adsorbent with a wide pore size distribution

Russian Chemical Bulletin - A microporous carbon adsorbent MPU-007 with a wide pore size distribution (specific micropore volume W0 calculated within the framework of the theory of micropore volume...     

Study of carbon black obtained by pyrolysis of waste scrap tyres

Waste scrap tyres were thermally decomposed under various conditions. Decompositions were followed by the TGA method. Specific heating regimes were tested to obtain optimal structural properties of resulting pyrolytic carbon black produced by pyrolysis of scrap tyres and the process was characterized in temperature interval from 380 to 1,200 °C and heating rate 10, 20 and 50 °C min^?1 under nitrogen atmosphere. The original scrap tyres and pyrolytic carbon black were characterized by Raman and Fourier transform infrared spectroscopy methods. Textural properties were also determined. Effect of temperature and heating rate on process of pyrolysis of scrap tyres was observed. Shifting of temperature of maximum pyrolysis rate to lower value and spreading of DTG peak is caused by increasing heating rate. Temperature 570 °C was sufficient for total scrap tyres pyrolysis. Graphitic and disordered structure was distinguished in the formed carbon black by Raman spectroscopy. With increasing temperature, heating rate and weight loss, the amount of the graphitic structure was reduced at the expense of disordered structure. Destruction of nonporous scrap tyres and formation of porous structure took place at higher temperature. Porous carbon black is formed above 380 °C, specific surface area increased up to 88 m² g^?1 .     

Spectrophotometric determination of the total concentration of sulfonamides in milk after adsorption separation using magnetic hypercrosslinked polystyrene

An approach is proposed to the estimation of the total concentration of sulfonamides in milk based on their adsorption isolation and preconcentration from whole milk with magnetic hypercrosslinked polystyrene followed by the spectrophotometric determination in an acetonitrile eluate by the reaction with p-dimethylaminocinnamaldehyde. The procedure was used for the determination of the total concentration of sulfonamides in milk at a level of the maximum residue limits.     

间氨基酚修饰超高交联吸附树脂的合成及吸附性能

合成了间氨基酚修饰超高交联吸附树脂(MMAR)。用红外光谱等进行表征,并用于吸附水溶液中2-氨基吡啶的研究。热力学研究结果表明,Freundlich吸附等温方程能够对静态吸附等温线进行很好的拟合。吸附焓变ΔH0,其绝对值小于46 KJ.mo-l1,表明以物理吸附为主以及该吸附剂容易脱附的特征;△G0,说明吸附是自发行为;△S0,表明吸附质分子在树脂表面上的运动受到了限制。动力学研究结果表明,吸附符合一级动力学方程,吸附速率随着温度的升高而增大,颗粒内扩散是速率控制步骤之一。表观活化能Ea10 KJ.mo-l1,说明吸附较容易进行。