In an investigation of the reaction of chlorine with carbon surfaces and the relationship between chlorine fixation and other heteroatoms (such as oxygen and hydrogen) on the surface, various porous carbons have been treated with gaseous chlorine. The diversity of the carbons was depicted not only by precursor material (coal, coconut shell, sugar, polymer) and porosity, but also by pretreatment which altered the surface oxide concentration or ash content. After chlorination, all of the samples showed a reduced uptake of water vapour at saturation, but calorimetric studies showed that the molar enthalpy of adsorption of water is unaffected by the presence of chlorine on the surface and remains dependant on the concentration of surface oxide sites. However, the chlorinated samples were determined to be more acidic than the surface oxide concentration indicated, suggesting an inductive effect of chemisorbed chlorine. The fixation of chemisorbed chlorine on the carbon surface showed no correlation with the ash content of the original carbon. (C) 1998 Elsevier Science Ltd. All rights reserved. References: 19
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