Activated carbon surface chemistry

J.S. Mattson and H.B. Mark, Activated Carbon Surface Chemistry and Adsorption from Solution, Marcel Dekker, 1971. 

Li, L., QuirJivan, P.A., and Knappe, D.R.U. (2002). Effect of activated carbon surface chemistry and pore structure on the adsorption of organic contaminants from aqueous solution. Carbon, 40, 2085—100. 

Mattson, J.S. and Mark, H.B., Jr. Activated Carbon — Surface Chemistry and Adsorption from Solution. M. Dekker, New York 1971. 

P, Matson and H.B. Mark, Activated carbon surface chemistry and adsorption from solution, Dekker, New York, 1971. 

The preparation of active carbons from different source raw materials and using different techniques, their porous and surface chemical structures, have been discussed in details in the book Active Carbon Because this book is concerned more with active carbon adsorption, a brief discussion about the more important aspects of active carbon surface chemistry are covered in this book. 

The analysis method of modified activated carbon surface chemistry functional groups... 

Li, L., Quinlivan, P., and Knapp, D.D.R.U., "Effects of Activated Carbon Surface Chemistry and Pore Structure on the Adsorption of Organic Contaminants from Aqueous Solution," Carbon. 2002 40 2085-2100. 

Activated Carbon Surface Chemistry and Adsorption from Solution... 

Ania CO, Bandosz TJ. Surface Chemistry of Activated Carbons and its Characterization In Activated Carbon Surfaces in Environmental Remediation, Bandosz, T J, Ed. Elsevier, Oxford, 2006.159-230. 

N-doping has already been reported for ACF and activated carbon [150,152], It is well known that the uptake pressure and the shape of the H20 isotherm are functions of both micropore size and surface chemical properties. In this case, however, the influence of micropore size can almost be excluded and the observed difference in the uptake pressure be attributed solely to carbon surface chemistry. It is therefore reasonable to conclude that the inner pore surface of the N-doped carbon is more hydrophilic than that of the undoped one. Since the O content of the former carbon is lower than that of the latter, the above results indicate that in this case the presence of N groups is more effective for H20 adsorption. 

The objective of this study is to evaluate which features of activated carbon surfaces are important for adsorption of acetaldehyde. The evaluation is based on the values of isosteric heats of adsorption, which reflect the strength of molecule interactions with the sorbent surface. After oxidation and urea modification the changes in surface chemistry and porous structure occurred. Those changes are expected to affect the dispersive and specific interactions of acetaldehyde with the activated carbon surfaces. 

In addition to pore size distribution, the surface chemistry of the activated carbon can have an important influence on the adsorption of certain compounds. As the adsorptive surface of most activated carbons is hydrophobic, they are best suited for the removal of neutral organic molecules, while polar and ionic compounds show much less affinity for adsorption. For the adsorption of polar compounds such as phenol, research has shown that the carbon surface chemistry is more relevant than the total available adsorption capacity or surface area [72-74]. It has been found that the presence of acidic surface oxides, whose concentration can be increased by oxygen adsorption or chemical treatment, leads to a decrease in adsorptive capacity for compounds such as phenols and increases the base adsorption capacity [75 [. 

Therefore the electrochemical response with porous electrodes prepared from powdered active carbons is much increased over that obtained when solid electrodes are used. Cyclic voltammetry used with PACE is a sensitive tool for investigating surface chemistry and solid-electrolyte solution interface phenomena. The large electrochemically active surface area enhances double layer charging currents, which tend to obscure faradic current features. For small sweep rates the CV results confirmed the presence of electroactive oxygen functional groups on the active carbon surface. With peak potentials linearly dependent on the pH of aqueous electrolyte solutions and the Nernst slope close to the theoretical value, it seems that equal numbers of electrons and protons are transferred. 

Which specific features of carbon surface chemistry need to be known, in both qualitative and quantitative terms, in order to be able to optimize an activated carbon for a specific pollution control task ... 

The historically popular concept of hydrolytic adsorption, which in fact obscures the key role of carbon surface chemistry, has often been used to account for the pH effects. Thus, for example, Rosene and Manes [622] used a Polanyi-based model of competitive adsorption between benzoic acid and sodium benzoate. They criticize the approach taken by Ward and Getzen [677], especially with regard to anion interaction with a positively charged surface, and essentially ignore the amphoteric character of the activated carbon. 

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