The Role of Pore Size Distribution in Competitive Adsorption on Activated Carbon PDF Download

Author: Costas Pelekani
Publisher:
ISBN:
Category :
Languages : en
Pages : 588

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Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Roles of background compound molecular size and adsorbent pore size distribution in competitive adsorption on activated carbon.

Author: Costas Pelekani
Publisher:
ISBN:
Category :
Languages : en
Pages : 208

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Author: John W. Patrick
Publisher: John Wiley & Sons
ISBN:
Category : Science
Languages : en
Pages : 352

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Book Description
Porosity in carbons often means different things to different people depending largely on the different applications of the various carbon materials. On the one hand, users involved in gas purification or respiratory protection are concerned primarily with microporosity, and at the other extreme, the user of carbon in the form of metallurgical coke is concerned with macroporosity because of its influence on the mechanical properties of the coke. Between these extremes there is a range of applications which rely on different aspects of the nature of the porous structure and the characterization required reflects the particular application in mind. This characterization of a wide diversity of porous structures presents some problems. However recent developments have produced some solutions, for example computerized image analysis has facilitated the measurement of pore shape and size. The eleven chapters in this book present an analysis of the current methods of characterization and the role of various aspects of carbon porosity in some representative and diverse applications.

Author: Mohammed Y. Osman
Publisher:
ISBN:
Category : Carbon, Activated
Languages : en
Pages : 438

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Author: Colorado. University. Chemical Engineering Department
Publisher:
ISBN:
Category : Carbon, Activated
Languages : en
Pages : 108

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Author: Eduardo J. Bottani
Publisher: Elsevier
ISBN: 0080559425
Category : Technology & Engineering
Languages : en
Pages : 773

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Book Description
Adsorption by Carbons covers the most significant aspects of adsorption by carbons, attempting to fill the existing gap between the fields of adsorption and carbonaceous materials. Both basic and applied aspects are presented. The first section of the book introduces physical adsorption and carbonaceous materials, and is followed by a section concerning the fundamentals of adsorption by carbons. This leads to development of a series of theoretical concepts that serve as an introduction to the following section in which adsorption is mainly envisaged as a tool to characterize the porous texture and surface chemistry of carbons. Particular attention is paid to some novel nanocarbons, and the electrochemistry of adsorption by carbons is also addressed. Finally, several important technological applications of gas and liquid adsorption by carbons in areas such as environmental protection and energy storage constitute the last section of the book. The first book to address the interplay between carbonaceous materials and adsorption Includes important environmental applications, such as the removal of volatile organic compounds from polluted atmospheres Covers both gas-solid and liquid-solid adsorption

Author: Detlef R. U. Knappe
Publisher: IWA Publishing
ISBN: 1843398419
Category : Science
Languages : en
Pages : 100

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Many water treatment plants need to remove objectionable trace organic compounds, and activated carbon adsorption is often the best available technology. Utilities face the challenge of having to choose from a large variety of activated carbons, and iodine number or BET surface area values are often utilized in the selection process. Although neither parameter correlates well with adsorption capacities, alternative activated carbon selection criteria based on fundamental adsorbent and adsorbate properties are lacking to date. The first objective of this research was to systematically evaluate the effects of activated carbon pore structure and surface chemistry on the adsorption of two common drinking water contaminants: the relatively polar fuel oxygenate methyl tertiary-butyl ether (MTBE) and the relatively nonpolar solvent trichloroethene (TCE). The second objective was to develop simple descriptors of activated carbon characteristics that facilitate the selection of suitable adsorbents for the removal of organic contaminants from drinking water.Originally published by AwwaRF for its subscribers in 2003 This publication can also be purchased and downloaded via Pay Per View on Water Intelligence Online - click on the Pay Per View icon below

Author: Li Ding
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Activated carbon adsorption is widely used in water treatment for removal of various organic micropollutants; nonetheless, the presence of natural organic matter (NOM) in source water can reduce its efficiency for micropollutant removal. NOM has been shown to compete with target contaminant via different mechanisms: direct competition for available adsorption sites which reduces equilibrium capacity for target compounds, blocking of pore entrance which reduces diffusion rate of the target compounds, and covering of surface sites which may actually enhances diffusion rate of the target compounds. The objective of this dissertation study was to further elucidate the individual competitive effects, to investigate how pore sizes of adsorbents and molecular structure of competing compounds affect competition and to gain a comprehensive understanding of the competitive adsorption. Atrazine, a widely used herbicide in the United States, was used as the trace-level target contaminant and NOM from different source waters as well as NOM surrogates were used as the competing compounds. Powdered activated carbons (PACs) with different pore size distribution (PSD) were used. The PSD was found to have great influence on the pore blockage (PB) effect caused by NOM. The equilibrium capacity of the NOM used in this study was best correlated to the amount of pores of diameter 15-50 ©5, which was also inversely related to the magnitude of the pore blockage effect. Activated carbon that has more surface area in this pore size range had a smaller PB effect on atrazine adsorption kinetics at the same NOM loading. This finding indicated that mesopores are important in realizing adsorption capacity for trace compounds by alleviating the adverse PB effect. The site covering effect was confirmed with additional types of PACs and various competing compounds. More important, the correlation equation that describes the enhanced surface diffusion coefficient for atrazine as a function of the loading of the site-covering compounds was found to be independent of either the PAC type or the competing compound type. The key component was to quantify the competing compound as the equivalent background compound (EBC), which reflected the extent of active sites being covered. iii The site competing effect, the site covering effect and the pore blocking effect were evaluated for five NOM surrogates with different sizes. The smaller molecules were generally more effective in reducing the equilibrium capacity of the target compound. However, for molecules of similar molecular weight, elongated molecules tended to have more equilibrium effect than round molecules. From a kinetic perspective, the enhancement in diffusivity was within one order of magnitude for all five surrogates, while the extent of the PB effect was greatly relying on molecular size that large-sized surrogates caused a much stronger PB effect. Therefore, the overall kinetic effect was dependent on molecular size and the PB effect was usually dominant except for very small molecules. Consistent with the enhanced kinetics associated with pre-adsorbed site-covering competing compounds, atrazine preloading was found to also increase the diffusion coefficient of atrazine, and the extent of enhancement caused by atrazine was greater than that caused by competing compounds. Several explanations were proposed for the difference, which include the micropore filling hypothesis and the artifact associated with the EBC method that was used for site-covering loading quantification.

Author: E.M. Thurman
Publisher: Springer Science & Business Media
ISBN: 9789024731435
Category : Science
Languages : en
Pages : 524

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This book is written as a reference on organic substances in natural waters and as a supplementary text for graduate students in water chemistry. The chapters address five topics: amount, origin, nature, geochemistry, and characterization of organic carbon. Of these topics, the main themes are the amount and nature of dissolved organic carbon in natural waters (mainly fresh water, although seawater is briefly discussed). It is hoped that the reader is familiar with organic chemistry, but it is not necessary. The first part of the book is a general overview of the amount and general nature of dissolved organic carbon. Over the past 10 years there has been an exponential increase in knowledge on organic substances in water, which is the result of money directed toward the research of organic compounds, of new methods of analysis (such as gas chromatography and mass spectrometry), and most importantly, the result of more people working in this field. Because of this exponential increase in knowledge, there is a need to pull together and summarize the data that has accumulated from many disciplines over the last decade.