Thermodynamic parameters of adsorption of isomeric chloronaphthalenes on graphitized thermal carbon black

Henry's constants and the heats of adsorption of isomeric chloronaphthalenes on graphitized thermal carbon black were calculated by the semiempirical molecular statistical method. The calculated data were compared with experimental results. The best agreement was achieved when corrections for the interaction of the Cl atom with the C atom of the adjacent benzene ring and the presence of other Cl atoms inortho-positions are introduced in calculations of the atom-atomic potential. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 8, pp. 1484–1489, August, 1999.     

Calculation of henry constants for the adsorption of isomeric phenylenediamines on graphitized thermal carbon black

Henry constants for the adsorption of o- and p-phenylenediamines on the surface of graphitized thermal carbon black within the temperature range 433–479 K were calculated by the molecular statistical method. The parameters of the atom-atom potential function of intermolecular interaction between the nitrogen atom in aniline and isomeric phenylenediamines and the carbon atom of the basal face of graphite were determined. It was shown that an intramolecular H bond influenced the geometry and adsorption properties of o-phenylenediamine.     

Adsorption and Vibration of Carbon on Low Index and Defect Nickel Surface

The 5‐parameter Morse potential of interaction between carbon and the nickel surface was constructed. We studied the adsorption and vibration of carbon atom on Ni(100), Ni(110) and Ni(111) single crystal low index surfaces and obtained the data of adsorption sites, adsorption geometry, binding energy and eigenvibration etc., which were in good agreement with the experimental results. Meanwhile, the influence of step defect on Ni(100) surfaces for carbon adsorption was also investigated.     

Hydroalumination of a Chlorotrialkynylsilane: Spontaneous Stepwise 1,3‐Dyotropic Rearrangement via an Intermediate Silyl Cation

A new functionalised alkynylsilane, Cl‐Si(C?C‐CMe₃)₃ ( 3 ), was obtained by a facile multistep synthesis. Treatment of 3 with equimolar quantities of the hydrides H‐M(CMe₃)₂ (M=Al, Ga) gave the mixed alkenyl‐di(alkynyl)silanes, in which the chlorine atom adopts a bridging position between the aluminium and silicon atoms. Dual hydrogallation of 3 resulted in the formation of a di(alkenyl)‐alkynylsilane containing two gallium atoms, one of which is coordinated to the chlorine atom, and the second is bonded to the α‐carbon atom of the remaining alkynyl group. A tert‐butylsilane was unexpectedly formed by a unique 1,3‐dyotropic chlorine–tert‐butyl exchange for the corresponding dialuminium compound. One aluminium atom is bonded to a tert‐butyl group, a terminal chlorine atom and the α‐carbon atom of the ethynyl moiety; the second is coordinatively unsaturated, with two terminal tert‐butyl substituents. High‐level quantum‐chemical calculations favour a stepwise dyotropic rearrangement with an intermediate cationic silicon species over a simultaneous tert‐butyl–chlorine migration via a five‐coordinate silicon atom in the transition state.     

Theoretical study of the atrazine pesticide interaction with pyrophyllite and Ca2+‐montmorillonite clay surfaces

Atrazine, a pesticide belonging to the s‐triazine family, is one of the most employed pesticides. Due to its negative impact on the environment, it has been forbidden within the European Union since 2004 but remains abundant in soils. For these reasons, its behavior in soils and water at the atomic scale is of great interest. In this article, we have investigated, using DFT, the adsorption of atrazine onto two different clay surfaces: a pyrophyllite clay and an Mg‐substituted clay named montmorillonite, with Ca²⁺ compensating cations on its surface. The calculations show that the atrazine molecule is physisorbed on the pyrophyllite surface, evidencing the necessity to use dispersion‐corrected computational methods. The adsorption energies of atrazine on montmorillonite are two to three times larger than on pyrophyllite, depending on the adsorption pattern. The computed adsorption energy is of about −30 kcal mol⁻¹ for the two most stable montmorillonite‐atrazine studied isomers. For these complexes, the large adsorption energy is related to the strong interaction between the chlorine atom of the atrazine molecule and one of the Ca²⁺ compensating cations of the clay surface. The structural modifications induced by the adsorption are localized: for the surface, close to substitutions and particularly below the Ca²⁺ cations; in the molecule, around the chlorine atom when Ca²⁺ interacts strongly with this basic site in a monodentate mode. This study shows the important role of the alkaline earth cations on the adsorption of atrazine on clays, suggesting that the atrazine pesticide retention will be significant in Ca²⁺‐montmorillonite clays. © 2016 Wiley Periodicals, Inc.     

Thermodynamic parameters of adsorption of adamantane and its derivatives on graphitized thermal carbon black

The adsorption equilibrium constants for adamantane, 1-fluoro-, 1-chloro-, 1,3-difluoro-, 1,3-dichloro-, 1,3-dibromo-, and 1-hydroxyadamantane, and methyl 1-adamantyl ketone were determined by gas chromatography. The results were compared with molecular statistical calculations based on the known atomic-atomic potentials of the interaction of atoms of the sorbate molecule with the C atom of graphitized thermal carbon black (GTCB). The experimental adsorption heats exceed the calculated values by 3-10 kJ mol^-1. The reasons for this divergence are discussed. The changes in the adsorption entropy show that the molecules of the studied compounds form a layer of the ideal dimeric gas on the GTCB surface upon adsorption.     

Ab Initio Calculation of the Structure of 5-Chloro-1,2,4-triazole

Three tautomeric forms of 5-chloro-1,2,4-triazole were calculated using the Hartree-Fock (ab initio) and Meller-Plesset methods in the 6-31G(d) basis. The ³⁵Cl NQR parameters were calculated using the occupancies of the 3p-components of the valence p-orbitals of the chlorine atom. The structure of this triazole was derived from the data obtained.     

Carbon-13 NMR spectra of DDT,its analogues and related compounds

Carbon-13 NMR spectra of mono- and disubstituted aromatic compounds including DDT, its analogues, homologues, derivatives and certain model compounds have been studied. The Savitsky scheme of carbon chemical shifts in disubstituted benzenes is applicable to these compounds. The data obtained show that in mono- and disubstituted aromatic compounds containing two different substituents in the α- and β-positions of the side chain, the substituted ring carbon atom shifts follow the additivity rule and can be calculated from substituent increments. Mutual effects of substituents in the ring and in the side chains are analysed. The chlorine atoms in α-position to the phenyl ring give rise to an additive α-effect of about 25 ppm, as in perchloroalkanes. The influence of a β-chlorine atom in the side chain on the substituted carbon atom in the ring is, however, only 3 ppm as against the usual value of about 10 ppm for the β-effect in alkyl chains. Moreover, the first β-chlorine substituent has no noticeable influence on the substituted ring carbon chemical shift: the effect of 3 ppm is transferred to the para-carbon atom almost without attenuation. The ring substituted carbon atom signal shifts caused by the γ-effect of chlorine in the side chain are similar to those observed in aliphatic chains. The ortho-chlorine substituents shift the side chain α-carbon atom signal by 3.6-5.2 ppm to high field compared to para-chlorophenyl compounds. This is similar to the chlorine γ-effect in aliphatic chains.     

Adsorption Energetics of NO and CO on Pt(111)

The adsorption energetics of NO and CO on Pt(111) are studied using an ab initio embedding theory. The Pt(111) surface is modeled as a three-layer, 28-atom cluster with the Pt atoms fixed at bulk lattice sites. Molecular NO is adsorbed at high symmetry sites on Pt(111), with the fcc threefold site energetically more favorable than the hcp threefold and bridge sites. The calculated adsorption energy at the fcc threefold site is 1.90 eV, with an N-surface distance of 1.23 Å. The NO molecular axis is perpendicular to the Pt(111) surface. Tilting the O atom away from the surface normal destablizes adsorbed NO at all adsorption sites considered. On-top Pt adsorption has been ruled out. The Pt(111) potential surface is very flat for CO adsorption, and the diffusion barriers from hcp to fcc sites are 0.03 eV and less than 0.06 eV across the bridge and the atop sites, respectively. Calculated adsorption energies are 1.67, 1.54, 1.51, and 1.60 eV at the fcc threefold, hcp threefold, bridge, and atop sites, respectively. Calculated C-surface distances are 1.24 Å at the fcc threefold site and 1.83 Å at the atop site. It is concluded that NO and CO adsorption energetics and geometries are different on Pt(111).     

大孔交联聚(对乙烯基苄基苯胺)树脂对苯酚的吸附

由氯甲基化聚苯乙烯合成了大孔交联聚(对乙烯基苄基苯胺)树脂, 测定了其对正己烷和水中苯酚的吸附等温线, 计算了吸附焓. 结果表明, 苯胺基树脂主要是通过氢键吸附正己烷中苯酚的, 树脂负载的功能基氮原子和苯环都作为氢键受体与苯酚的羟基氢原子形成氢键, 而其对水中苯酚的吸附是基于氢键和疏水作用.     

Adsorption of Nitrogen on Silica Gel Over a Large Range of Temperatures

To study the mechanism of physical adsorption of supercritical gases, the adsorption equilibria of N₂ on silica gel for 103–298 K using 20 K increments and pressures up to 10 MPa were measured. A transition of the adsorption mechanism was proven on crossing the critical temperature, but the transition way observed is different from that observed with activated carbon. This causes a difference in the locations of the linear section of the n- _g isotherm at the near-critical temperature. Although the isotherm type is different on silica gel and on activated carbon in the sub-critical region, all isotherms in the supercritical region can be well modeled by a single model. It leads to the argument that the adsorption mechanism of supercritical gases is identical no matter what kind of adsorbent is used.     

Adsorption of helium on zeolite NaA

Isotherms of helium adsorption on zeolite NaA were measured by the volumetric method under static conditions at 23–50 K and pressures from 1 Pa to 65 kPa. The Henry constants and the initial heat of helium adsorption were calculated; the isosteric heat was calculated, and its dependence on the adsorption was determined.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1291–1292, May, 1996.     

Adsorption on nonporous and supermicroporous adsorbents

The mean values of the characteristic energy of C₆H₆ adsorption in large micropores were calculated from the adsorption isotherms of benzene vapor on carbon blacks. The supermicropores are characterized by the significant dispersion of the adsorption potential resulted from the pore-size distribution, which imparts the polymolecular character to adsorption. The effect of enhancement of the characteristic energy of adsorption was analyzed, which was caused by the overlap of the force fields of the opposite pore walls and the reduction of the adsorption film surface with micropore volume filling. The both factors are comparable by magnitude and depend on the micropore sizes.     

The adsorptivity of organic substances with various physico-chemical properties

The adsorption isotherms of benzene,n-hexane, cyclohexane, and 1,2-dibromo-1,1,2,2-tetrafluoroethane on a nonporous carbon adsorbent, carbon black, were calculated from the results of a gas-chromatographic experiment at 373 K. A general equation of adsorption isotherm for vapors of organic substances on nonporous sorbents that was proposed earlier is shown to be valid in the range of relative pressures,p/p _s, of 10^–7–1 and temperatures of 293–373 K.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1381–1383, August, 1993.     

碳纳米管复合微球修饰L-色氨酸及其对LDL的吸附性能

本文以多孔碳纳米管/活性炭复合微球为载体, 以L-色氨酸为配基, 采用环氧氯丙烷偶联法, 制得修饰L-色氨酸的碳纳米管/活性炭复合微球(L-CNTs/AC)。采用扫描电镜、氮气吸附、傅立叶红外光谱、热分析、X射线光电子能谱等对复合微球进行表征;通过体外静态吸附法对其低密度脂蛋白(LDL)吸附能力进行初步研究。结果表明:环氧氯丙烷偶联法可接枝上L-色氨酸。复合微球中碳纳米管加入量越多, 对LDL的吸附能力越强;当碳纳米管加入量为45wt%时, 对LDL的吸附量达4.623 mg·g^-1, 是未添加碳纳米管的2.3倍多。这是因为碳纳米管不仅可促进复合微球中20~100 nm孔的形成, 而且还可促进复合微球配基修饰量的增多, 从而大大增强了复合微球对LDL的吸附能力。此复合微球可望开发成一种新型的血液灌流LDL吸附剂。     

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.     

The cell effect in adamantane adsorption on graphitized thermal carbon black

Nonequivalence of the nodal and bridging carbon atoms of the adamantane molecule during adsorption on graphitized thermal carbon black was shown. The nonequivalence is related to a special type of intermolecular interaction, the cell effect. Based on the experimental data and the molecular statistical calculations of Henry's constants, the parameters of atomatom potentials for the nodal carbon atoms in the adamantane molecule were found. This atom-atom potential differs from that known for the carbon atom in the sp³-hybridization. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 849–853, May, 2000.     

Donor—acceptor interactions of substituted benzenes with molecular chlorine and carbon disulfide

CNDO molecular orbital calculations have been performed to analyze donor—acceptor interactions between molecular chlorine and benzene, toluene, mesitylene and hexamethylbenzene and the, as yet, unreported chlorine—hexafluorobenzene and carbon disulfide—benzene pairs. The stabilization energy and the dipole moment and its derivative (?p/?R_CICI) calculated for the benzene—chlorine complex are in good agreement with the estimated experimental values. The trends in the experimental stabilization energies and the Cl-Cl vibrational frequencies with increasing methyl substitution appear to be well reproduced by the calculations. The charge transferred from the benzene donor is polarized toward the outer chlorine atom or sulfur atom. For hexafluorobenzene-chlorine the direction of electronic charge polarization is reversed from that of the benzene and methylbenzene complexes. The calculated results are discussed within the framework of Muliiken's simplified resonance theory for complexes.     

金属Pt表面水蒸汽分子吸附的量子力学计算

基于电子与振动近似方法和密度泛函B3LYP理论, 氧和氢原子选择6-311G**基函数, Pt选择赝势基组LanL2DZ, 优化得到Pt-OH₂结构和微观性质, 稳态结构Pt-H₂O分子中, Pt与H₂O不在同一平面, Pt倾向于与O原子结合. 计算了100～898.15 K温度下, 水蒸汽分子在Pt表面吸附反应的热力学函数值和平衡压力, 拟合得到ΔS⁰,ΔH⁰, ΔG⁰, ln p与温度的函数关系. 室温以上ΔG⁰＞0 kJ•mol^－1, 水蒸汽分子在Pt表面不能稳定吸附; 200 K以下, ΔG⁰＜0 kJ•mol^－1, 能够稳定吸附. 计算了不同温度下水蒸汽分子在Pt表面发生解离反应的ΔG⁰和平衡压力, 室温以上ΔG⁰＞0 kJ•mol^－1. 100～898.15 K温度下, 水蒸汽分子在Pt表面不容易发生解离, 实际反应过程中以完整分子形式参与反应.