Gas chromatographic investigation of adsorption equilibria on graphitized thermal carbon black

Summary Retention volumes and heats of adsorption at low surface coverages of graphitized thermal carbon black (GTCB) for C₆–C₁₄ aromatic hydrocarbons have been determined. The dependence of heats of adsorption of these molecules on their structure and the number of carbon atoms in the molecule have been investigated. Substitution in the ring in methylbenzenes is not equivalent to the lengthening of the side-chain in the isomers of n-alkylbenzenes and gives rise to a much greater increase in the retention volumes and heats of adsorption.     

Gas chromatographic analysis of water phenolic pollutants using acid-washed graphitised carbon black

Summary The fractionation of eleven phenols which may be contaminants in drinking water has been accomplished by using acid-washed graphitised carbon black modified with trimesic acid and PEG 20 M.     

Gas chromatographic properties of methacrylate polymers modified by silver nanoparticles

Russian Chemical Bulletin - The gas chromatographic properties of the porous methacrylate polymers, copolymers of 2,3-epoxypropyl methacrylate (2,3-EPMA) and ethylenedimethacrylate (EDMA), modified...     

Gas chromatography-mass spectrometry in the study of the adsorption of sulfur-containing amino acids on graphitized thermal carbon black

Summary Gas chromatographic — mass spectrometric study of the trifluoroacetyl-methyl esters of sulfur- and hydroxyl-containing amino acids such as methionine, cysteine, D-,-dimethylcysteine (D-penicillamine), serine, and threonine was carried out. Sterling hydrogen treated graphitized thermal carbon black (HTGTCB) was used as the adsorbent. The Henry's constants, and the initial differential adsorption heats of these amino acid derivatives were determined on the HTGTCB surface by gas chromatography.Introduction of two methyl groups into the -position of a cysteine molecule (,-dimethylcysteine) stimulates the intramolecular nonvalent interactions increasing the internal rotation barriers in the molecule. This is revealed in the sharply reduced retention of the ,-dimethylcysteine derivative on the HTGTCB surface (as compared to the cysteine derivative) and it also influences the fragmentation pathways under electron impact.Deceased.     

Styrene butadiene rubber/carbon black composites modified by imidazole derivatives

In this study, the imidazole derivatives such as 2-undecylimidazole (UI) and 2-mercapto-1-methylimidazole (MMI) are utilized to work as novel additives for modifying styrene butadiene rubber (SBR)/carbon black (CB) composites. The imidazole groups on UI and MMI can be hydrogen-bonded with oxygen-containing groups on the surface of CB, and the undecyl or thiol groups can be reacted with the SBR chains via physical entanglement or thiol-ene chemistry. The results demonstrate that the static and dynamic mechanical performances of SBR/UI and SBR/MMI composites are significantly improved over those of the SBR composite. Compared with blank SBR composite, the tensile strength, modulus at 300% elongation, and tear strength of SBR/MMI-1.0 are greatly improved by 30, 42, and 18%, respectively. The rolling resistance of SBR/MMI-1.0 is reduced by 10.4%, and the wet grip property is increased by 4.0%. The superiority of appropriate MMI content (1.0 phr in our work) in the enhancement for the overall performance of SBR composites is attributed to the promotion of a good dispersion of CB throughout the SBR matrix and the enhanced interfacial interactions between CB and the SBR matrix. This work may enlarge the potential applications of modified CB to fabricate high-performance rubber composites.     

A study of adsorption of some bicyclo [2.2.1] heptane derivatives on graphitized thermal carbon black

Retention volumes at zero sample size (Henry's constants of adsorption equilibrium), Kovats' indices and the changes in differential molar internal energy and entropy upon adsorption are found for bicyclo[2.2.1] heptane (norbornane), six isomeric dimethylnorbornanes and 7,7′-bisnorbornane by gas adsorption chromatography on packed columns with GTCB. A molecular statistical calculation of the thermodynamic characteristics of adsorption is carried out and the results are compared with experimental data.     

Adsorption of molecules of different structure on graphitized thermal carbon black IV. Gas chromatographic investigation of adsorption of aldehydes,ketones and alcohols on hydrogen-treated graphitized thermal carbon black

Summary Retention volumes (Henry constants) and differential molar change of internal energy at low surface coverages on hydrogen-treated graphitized thermal carbon black (HTGTCG) for aldehydes, ketones and alcohols have been determined. An additional hydrogen treatment of graphitized thermal carbon black at 1000°C (GTCB) was undertaken to remove chemical inhomogeneity of the surface. After this treatment the peaks of oxygenated hydrocarbon derivatives became more symmetrical. Reduction of retention volumes after this treatment was observed only for substances with short hydrocarbon chains. The dependence during adsorption on the structure of, and number of carbon atoms in, aldehydes, ketones and alcohols has been investigated. The Kovats' indices for the chromatography on HTGTCB were obtained and used for identification.     

Gas chromatographic study of acetyl derivatives of chlorinated 4-hydroxybenzaldehydes

Summary The GC retention times of 4-hydroxybenzaldehyde and its chloro derivatives have been measured on three nonpolar capillary columns. Multiple linear regression analysis has been used to explain the mobility of chlorinated compounds relative to the reference compound 4-hydroxybenzaldehyde. The most important effects have shown to be due to the number of chlorine atoms and the substituents ortho to the formyl group. Other effects have also been observed but found to be unable to explain the GC data.     

The tumour-localizing properties of porphyrin derivatives

The tumour-localizing abilities of various kinds of porphyrin derivatives in tumour-bearing hamsters were assessed by nitrogen-pulsed laser spectrofluorometry (N2-PLS). On examination of porphine derivatives (from haemoglobin), it was found that the dimer and acetylated and amidated compounds had a high affinity for tumour tissue; the dimer and hydroxylated compound of phorbine derivatives (from chlorophyll) also showed a high affinity. Furthermore, of the metalloporphines (gallium, zinc and indium complexes), those which contained hydrophilic groups showed a high affinity for tumour tissue; of the metallophorbines (gallium, zinc and indium complexes), those which contained hydrophobic groups showed a high affinity. A correlation was found between the side-chain structure of the porphyrins and metalloporphyrins and their affinity for tumour tissue.     

A study of the adsorption properties of modified layered silicate

The composition and structure of vermiculite samples modified successively with hydrochloric acid and chitosan are studied with the use of X-ray fluorescence and X-ray-diffraction analyses, as well as IR spectroscopy. The adsorption characteristics of the samples with respect to nitrogen and different dyes are determined, and the parameters of their porous structure are calculated. It is shown that the acid treatment of initial vermiculite drastically increases the content of silicon (in the form of amorphous silica), changes the layered structure of the silicate, and substantially enhances its specific surface area and pore volume.     

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.     

Thermodynamics of the adsorption of organic molecules on graphitized carbon black modified with a monolayer of 5-hydroxy-6-methyluracil

Thermodynamic characteristics of the adsorption of alkanes, alcohols, arenes, and esters on graphitized carbon black with a deposited monolayer (0.17%) of 5-hydroxy-6-methyluracil are studied by means of inverse gas chromatography at infinite dilution. It is established that size effects (violation of the additivity of molar changes in internal energy and the entropy of adsorption for pairs of molecules of one homologous series that differ by one methyl group) are observed when organic molecules are adsorbed on the surface of the resulting adsorbent. The size effects are similar to those observed when 1% 5-hydroxy-6-methyluracil is deposited on graphitized carbon black. It is concluded that the observed violation of additivity is associated with cavities in the supramolecular structure.