Acid buffering capacity of basic carbons revealed by their continuous pK distribution

Conţescu, Adriana; Vass, Mihail; Contescu, Cristian I.; Putyera, Karol; Schwarz, John H.

doi:10.1016/s0008-6223(97)00168-1

Cited by 100 publications

(50 citation statements)

References 21 publications

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“…If these basic structures were present in C0 and C20, it should be expected that the TPD profiles show larger amounts, particularly of CO (28). Therefore, it can be concluded that the basic character of samples C0 and C20 is mainly due to π electrons on graphytic planes which can produce donor-acceptor interactions (3,(29)(30)(31)(32).…”

Section: Resultsmentioning

confidence: 99%

On the Characterization of Chemical Surface Groups of Carbon Materials

Domingo-Garcı́a¹,

López-Garzón²,

Pérez-Mendoza³

2002

Journal of Colloid and Interface Science

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Section: Resultsmentioning

confidence: 99%

On the Characterization of Chemical Surface Groups of Carbon Materials

Domingo-Garcı́a¹,

López-Garzón²,

Pérez-Mendoza³

2002

Journal of Colloid and Interface Science

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“…(Source: biochar from Cornell University; picture from EMU UNSW.) as a result of the oxidation of exposed C rings with a high density of p-electrons (Contescu et al 1998) and free radicals (MontesMorán et al 2004). If biochar is mixed with decomposable organic material, such as compost, weathering reactions (e.g.…”

Section: Methods Of Storage and Incorporationmentioning

confidence: 99%

“…However, in leaching environments, the pH will tend to decrease as these salts are lost from the system (Yao et al 2010); the magnitude of this decrease is determined by the intensity of the leaching and the acid-buffering capacity of the system. The pH around biochar particles would also initially increase due to the Lewis basicity of p-electrons (Contescu et al 1998) and then decrease as acidic functional groups are formed on biochar surfaces (Cheng et al 2006;Cheng and Lehmann 2009). In high-ash biochars, the pH increase due to basic salts may be larger than the pH decrease induced by surface oxidation even over longer time scales (Nguyen and Lehmann 2009).…”

Section: Dissolution-precipitation Reactionsmentioning

confidence: 99%

“…The oxidation of biochar is largely initiated through abiotic reactions boosted by the electron-donating properties of areas with a high density of p-electrons (Contescu et al 1998), and followed by the subsequent formation of O-containing functional groups at the surface of the biochar, some of them acidic in nature (see next section). The presence of free radicals in biocharsthe amount being dependent on pyrolysis process conditions (Feng et al 2004)-increases the reactivity towards oxidation, often to the point of being pyrophoric (Amonette and Joseph 2009).…”

Section: Redox Reactionsmentioning

confidence: 99%

“…While the nature of the acidic surface sites is well understood, the nature of basic sites on C surfaces is a controversial issue (Leon y Leon et al 1992;Contescu et al 1998;Montes-Morán et al 2004). Traditionally, oxygen-containing groups (e.g.…”

Section: Acidic and Basic Surface Charge Of Biocharsmentioning

confidence: 99%

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An investigation into the reactions of biochar in soil

et al. 2010

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Abstract.Interactions between biochar, soil, microbes, and plant roots may occur within a short period of time after application to the soil. The extent, rates, and implications of these interactions, however, are far from understood. This review describes the properties of biochars and suggests possible reactions that may occur after the addition of biochars to soil. These include dissolution-precipitation, adsorption-desorption, acid-base, and redox reactions. Attention is given to reactions occurring within pores, and to interactions with roots, microorganisms, and soil fauna. Examination of biochars (from chicken litter, greenwaste, and paper mill sludges) weathered for 1 and 2 years in an Australian Ferrosol provides evidence for some of the mechanisms described in this review and offers an insight to reactions at a molecular scale. These interactions are biochar-and site-specific. Therefore, suitable experimental trials-combining biochar types and different pedoclimatic conditions-are needed to determine the extent to which these reactions influence the potential of biochar as a soil amendment and tool for carbon sequestration.

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Carbons

Schlögl

2008

Handbook of Heterogeneous Catalysis

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The element carbon plays a multiple role in heterogeneous catalysis. In homogeneous catalysis it occurs of course as the most prominent constituent of ligand systems and will be treated as such there. Carbon-containing molecules are, in most catalytic applications, the substrates of the process under consideration. Deposits and polymers of carbon often occur as poisons on catalysts. Carbon deposition is the most severe problem in certain zeolite applications. In hydrogenation reactions carbon deposits are thought to act as modifiers for the activity of the catalyst and to provide selectivity by controlling the hydrogenationdehydrogenation activity of the metal part of the catalyst. Carbon deposits are even thought to constitute part of the active sites in some cases. Carbon is a prominent catalyst support material as it allows the anchoring of metal particles on a substrate which does not exhibit solid acid-base properties. Carbon is finally a catalyst in its own right allowing the activation of oxygen and chlorine for selective oxidation, chlorination and de-chlorination reactions. These multiple roles of the element carbon are in parallel with a complex structural chemistry giving rise to families of chemically vastly different modifications of the element. It is a special characteristic of carbon chemistry that many of these modifications cannot be obtained as phase-pure materials. This limits the exact knowledge of physical and chemical properties to a few archetype modifications, namely graphite and diamond. The reason for this poor definition of materials is found in the process of its formation. This is comprised of difficult to control polymerisation reactions. Such reactions will occur also in catalytic reactions with small organic molecules. The nature of carbon deposits will therefore reflect all the complexity of the bulk carbon materials. It is one aim of this article to describe the structural and chemical complexity of "carbon" or "soot" in order to provide an understanding of the frequently observed complexity of the chemical reactivity (e.g. in re-activation processes aiming at an oxidative removal of deposits). The surface chemistry of carbon which determines its interfacial properties is a rich field as a wide variety of surface functional groups are known to exist on carbon. The by far most important family of surface functional groups are those involving oxygen. Other prominent heteroatoms on the surface are hydrogen and nitrogen. This article focusses on the description and characterisation of oxygen surface functional groups. In the final section, selected case studies of carbon chemistry in catalysis will be discussed in order to illustrate characteristic properties of carbon materials as wanted or unwanted components in catalytic systems. Regarding the literature on basic properties of carbon materials, the reader is referred to the extensive collection of review papers published in the series Chemistry and Physics of Carbon. Editors P.L.

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Acid buffering capacity of basic carbons revealed by their continuous pK distribution

Cited by 100 publications

References 21 publications

On the Characterization of Chemical Surface Groups of Carbon Materials

On the Characterization of Chemical Surface Groups of Carbon Materials

An investigation into the reactions of biochar in soil

Carbons

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