Trichloroethylene Adsorption by Fibrous and Granular Activated Carbons:  Aqueous Phase, Gas Phase, and Water Vapor Adsorption Studies

Karanfil, Tanju; Dastgheib, Seyed A.

doi:10.1021/es0497936

Cited by 105 publications

(49 citation statements)

References 19 publications

(19 reference statements)

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“…GAC is milled away for production of PAC and some of the macropores are lost during this process. Since desorption is expected to be easier from macropores compared with mesoand micropores with greater adsorption energies, 12 desorption from the GAC particles was easier. But this effect should be limited since adsorption on macropores was very low due to the fact that macropores adsorb phenol by surface area and the contribution of macropores to the total surface area is limited.…”

Section: Desorption Studiesmentioning

confidence: 99%

“…This finding was obviously due to the significant change in the overall concentration range over which the hysteresis effect was quantified. In the literature it is stated that the sorption energy onto micropores is greater 12 than onto meso-or macropores. In our case, this excess phenol at the carbon dose of 4000 mg dm −3 should be certainly adsorbed with a smaller energy onto meso-or macropores rather than micropores.…”

Section: Desorption Studiesmentioning

confidence: 99%

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Effect of type of carbon activation on adsorption and its reversibility

Aktaş

Çeçen

2005

J of Chemical Tech & Biotech

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In biological treatment processes combined with the use of activated carbon, adsorbability and desorbability receive special attention. In particular, desorbability is of crucial importance for bioregeneration of activated carbon in these systems. This study aims to clarify the effect of the type of activated carbon on the extent of adsorption of phenol and the reversibility of adsorption. For this purpose, four different types of activated carbon: thermally-activated and chemically-activated powdered carbons (PAC), and their granular countertypes (GAC) with similar physical characteristics, were used. Adsorption and desorption isotherms showed that thermally-activated carbons, either in powdered or granular form, were better adsorbers for phenol than chemically-activated ones. However, apparently higher degrees of hysteresis (higher adsorption irreversibility) were calculated in the case of thermallyactivated carbons. Chemisorption was the dominant adsorption mechanism for thermally-activated carbons, whereas physisorption was dominant for chemically-activated ones. Degrees of hysteresis for the PACs were found to be only slightly higher than their GAC countertypes, but desorption was faster from the PACs. The results suggest that, rather than the physical form, the type of carbon activation and the chemical characteristics of the surface play a more important role on the adsorbability of phenol and its reversibility.

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Section: Desorption Studiesmentioning

confidence: 99%

Section: Desorption Studiesmentioning

confidence: 99%

Effect of type of carbon activation on adsorption and its reversibility

Aktaş

Çeçen

2005

J of Chemical Tech & Biotech

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“…Whereas, water adsorption result was obtained the surface hydrophilicity information, which is water adsorption range was only hydrophilic surface. [21][22][23] Accordingly, it was suggested that differences in affinity for water of the powder surface between products.…”

Section: )mentioning

confidence: 99%

Comparison of the Dissolution Rate of Ceftriaxone Sodium Preparations for Injection

Tange

Hattori

Otsuka

et al. 2013

CHEMICAL & PHARMACEUTICAL BULLETIN

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This study aimed to compare the dissolution rate of eight different formulations of ceftriaxone sodium preparation for injection, the original product and seven generic versions. The dissolution time was measured precisely as the point at which the freeze-dried ceftriaxone sodium preparation became a transparent solution on the addition of 0.9% sodium chloride solution. To investigate whether differences in the crystalline structure may explain the differences in dissolution rates, the eight products were subjected to X-ray diffraction (XRD) and differential scanning calorimetry (DSC). Powder surface characteristics were examined, including surface area, amount of water adsorbed, water interactions and morphology. The measurement of near-infrared spectroscopy of powder preparations was conducted, and we predicted dissolution time by partial least squares (PLS). The dissolution time of the eight products were different. There were no differences in XRD and DSC findings between the original and generic products, surface characteristics, i.e., surface area, morphology etc., were different between preparations. On near-infrared (NIR) spectroscopy, a good relationship was demonstrated between the actual and predicted dissolution time for each ceftriaxone preparation. The difference in dissolution time between the eight products was due to differences in powder surface characteristics, such as water interaction and crystal shape. Finally, it was shown that the dissolution rates of the products could be predicted by NIR analysis.Key words dissolution rate; near-infrared spectroscopy; X-ray diffraction; differential scanning calorimetry; generic drug; powder property Dissolution properties are important in the formulation design of pharmaceutical preparations, and improvement in dissolution rate is a critical issue in drug development for nonparenteral preparations. There are a number of mathematical models for dissolution profile.

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“…Karanfil and Dastgheib (2004) examined the adsorptive removal of trichloroethene from water by several activated carbons. They correlated the capacities to the proportion of micropores and hydrophilic surface groups.…”

Section: Introductionmentioning

confidence: 99%

Adsorption of aromatic trace compounds from organic solvents on activated carbons—experimental results and modeling of adsorption equilibria

et al. 2012

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Liquid phase adsorption is an important process for the removal of trace compounds from liquid matrices. Until today, research on liquid phase adsorption is less substantial than work on other thermal separation processes. The description of relevant mechanisms and interactions is difficult mainly because of lacking experimental data. This paper presents extensive isotherm measurements for the adsorption of organic trace compounds from organic solvents on activated carbons. A systematic variation of molecular structure of adsorptives and solvents enabled the identification of main structural factors dominating adsorption in these systems. The factors are polarity, extension and density of π electrons and sterical complexity. An analysis of the measured isotherms revealed incremental effects of functional groups and structural elements being characteristic for the adsorption capacities on activated carbons. Three consecutive empirical prediction models of adsorption equilibria are developed and compared. The empirical Freundlich equation appeared to be best suited for fitting the experimental data. The models apply an incremental concept permitting the calculation of adsorption isotherms on the basis of the structural increments of solvent and adsorptive molecules. The three models have a different extent of underlying data, a different number of parameters and a different range of application. The experimental data are predicted with satisfying accuracy for many engineering applications. The most sophisticated model has the most extensive range of application and manages on the smallest number of parameters.

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Trichloroethylene Adsorption by Fibrous and Granular Activated Carbons: Aqueous Phase, Gas Phase, and Water Vapor Adsorption Studies

Cited by 105 publications

References 19 publications

Effect of type of carbon activation on adsorption and its reversibility

Effect of type of carbon activation on adsorption and its reversibility

Comparison of the Dissolution Rate of Ceftriaxone Sodium Preparations for Injection

Adsorption of aromatic trace compounds from organic solvents on activated carbons—experimental results and modeling of adsorption equilibria

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