Physico-chemical applications of HPLC

El'tekova, N. A.; Eltekov, Yu. A.

doi:10.1007/bf02258994

Cited by 5 publications

(5 citation statements)

References 14 publications

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“…12 The effect of the relation of the number of molecules of water and the organic component of the solution in the adsorbed phase on the selectivity of adsorption from solution by activated carbon was recently investigated by Koganovski. 13 Eltekova et al 14 studied the adsorption of benzene from aqueous solutions on activated carbon. They applied the DR and DS (Dubinin-Stoeckli) equation to describe the adsorption data; however, for the DS equation a considerably better fit was observed.…”

Section: Introductionmentioning

confidence: 99%

Effect of the Carbon Surface Layer Chemistry on Benzene Adsorption from the Vapor Phase and from Dilute Aqueous Solutions

et al. 2005

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We present a complex study of benzene adsorption on chemically modified commercial activated carbons. The porosity of studied carbons is almost the same, whereas the chemical composition and the acid-base properties of surface layers differ drastically from amphoteric (initial de-ashed carbon D43/1, Carbo-Tech, Essen, Germany) and acidic (carbon modified with concentrated HNO3 and fuming H2SO4) to strongly basic (carbon modified with gaseous NH3). Benzene adsorption isotherms measured from aqueous solution at three temperatures (298, 313, and 323 K) and at the neutral pH level are reported. They are supported by studies of water and benzene adsorption from the gaseous phase (volumetric and calorimetric data) and the data of benzene temperature-programmed desorption (TPD). Moreover, the data of the enthalpy of immersion in water and benzene are also presented. Obtained data of benzene adsorption from the gaseous phase are approximated by applying the method of Nguyen and Do (ND) and the Dubinin-Astakhov (DA) equation. The data of adsorption from solution are described by the hybrid DA-Freundlich (DA-F) model. We show that there are similarities in the mechanisms of benzene adsorption from the gaseous phase and from aqueous solutions and that the pore-blocking effect is the main stage of the adsorption mechanism. This effect strongly depends on the polarity of the carbon surface. The larger the ratio of the enthalpy of carbon immersion in water to the enthalpy of immersion in benzene, the larger the reduction in adsorption from solution, compared to that in the gaseous phase, that is observed.

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Section: Introductionmentioning

confidence: 99%

Effect of the Carbon Surface Layer Chemistry on Benzene Adsorption from the Vapor Phase and from Dilute Aqueous Solutions

et al. 2005

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“…Comparative characteristics of the retention of the test compounds at the surface of Silochrom S-80 [13], the PG-101 porous pyrocarbon [14], and mesoporous cellulose are given in Table 3. Apart from the ä ç val- ELTEKOVA, ELTEKOV ues, the retention of the test compounds was characterized by the partition coefficient ä  of arene molecules between the adsorbent and the bulk phase and the Gibbs energy change ∆ F in the adsorption:…”

Section: Resultsmentioning

confidence: 99%

“…In gas chromatography with packed columns, graphitized soot with particles containing inclusions of virtually ideal graphite layers has found wide use as an adsorbent [1,3,4,7]. In gas chromatography with packed columns, graphitized soot with particles containing inclusions of virtually ideal graphite layers has found wide use as an adsorbent [1,3,4,7].…”

Section: Introductionmentioning

confidence: 99%

10.1007/s11124-008-2012-8

2000

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Competitive adsorption of anisole, benzaldehyde, benzoic acid, benzene, toluene, and phenol from dilute solutions in n -heptane at three chemically different porous adsorbents was studied by high-performance liquid chromatography (HPLC). The retention times of these compounds were used to calculate the equilibrium constants of the adsorption isotherms, the partition coefficients, and the Gibbs energy changes. The results obtained made it possible to estimate the Gibbs energy changes in the competitive adsorption of arenes leading to the formation of supramolecular surface compounds at cellulose and silica and the formation of arene clusters at the pyrocarbon surface from dilute solutions in n -heptane.

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“…Adsorption isotherms of different compounds on hydrophobic [8,9,17,20,[32][33][34][35] and hydrophilic [4,8,12,18,19,34,36] silicas are reported. There are in the literature few works [19,39] dealing simultaneously with both NP and RP-HPLC silicas.…”

Section: Introductionmentioning

confidence: 99%

“…Chromatography, is firmly established as an essential technique for physicochemical investigations [9][10][11][12][13][14], however, research by the liquid chromatographic method on adsorption of binary mobile phases solutions, has not considered the most used in the HPLC practice stationary phases: hydrophobic and hydrophilic silicagel. HPLC can be successfully applied to determine adsorption isotherms [6,7,9,12,[15][16][17], by different procedures [18] which lead to practically identical results [19,20] and it has been demonstrated that in the case of adsorbents used in HPLC, the derived adsorption data are in good agreement [8,9,18,21] with those obtained by using the static methods [2,22] for adsorption studies. A common feature of the HPLC procedures is speed.…”

Section: Introductionmentioning

confidence: 99%

HPLC study of the adsorption from solutions on two silicagels

1997

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SummaryIn this paper, we report and discuss the adsorption isotherms of hydro-organic mixtures and of compounds used as mobile phase in reversed phase and normal phase high performance liquid chromatography (RP-HPLC and NP-HPLC, respectively). This work is the first attempt to study the solid-liquid interface between two types of chromatographic silica surfaces and pure organic adsorbates from water and from organic eluents by HPLC. Frequently, among the dynamic techniques the method of choice for the measurement of an adsorption isotherm is frontal analysis. We suggest here the combination of the technique based on peak asymmetry calibration and peak profiles, which allows calculations directly from integration data. The group of systems studied permits the analysis of the intermolecular interactions on the silica surface. Particular attention was given to the system methanol-water and the measurement of the adsorption of n-octanol from methanol on RP-silica was also carried out.

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Physico-chemical applications of HPLC

Cited by 5 publications

References 14 publications

Effect of the Carbon Surface Layer Chemistry on Benzene Adsorption from the Vapor Phase and from Dilute Aqueous Solutions

Effect of the Carbon Surface Layer Chemistry on Benzene Adsorption from the Vapor Phase and from Dilute Aqueous Solutions

10.1007/s11124-008-2012-8

HPLC study of the adsorption from solutions on two silicagels

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