Adsorption behavior of propylamine on activated carbon fiber surfaces as induced by oxygen functional complexes.
In this study, the surfaces of activated carbon fibers (ACFs) were modified by nitric acid to introduce surface oxygen complexes and to observe the influence of those complexes on the propylamine adsorption of the ACFs. It was found that the oxygen complexes including carboxylic and phenolic groups were predominantly increased, resulting in the increase of total surface acidity. However, the specific surface areas and the total pore volumes of the modified ACFs were decreased by 5-8% due to the increased blocking (or demolition) of micropores in the presence of newly introduced complexes. Despite the decrease of textural properties, it was found that the amount of propylamine adsorbed by the modified ACFs was increased by approximately 17%. From the XPS results, it was observed that propylamine reacted with strong or weak acidic groups, such as COOH or OH, on the ACF surfaces, resulting in the formation of pyrrolic-, pyridonic-, or pyridine-like structures.
Comparative odor control performance of activated carbon and permanganated alumina
Abstract Activated carbon and permanganated alumina were compared with regard to their effectiveness in reducing the odor levels of air streams containing olefin. ester, aldehyde, ketone, amine, sulfide, mercaptan, decomposed crustacean shell vapor, or state tobacco vapor. In all cases, the odor-reducing effect of the activated carbon was much faster than that of the permanganated alumina. For the odors of stale tobacco and decomposed crustacean shells, the permanganated alumina, after it was reduced to MnO2, gave evidence of prolonged partial odor reduction, probably by serving as a catalyst for oxidation by air.
Ozonation of pyrimidines in aqueous solutions
Abstract The ozonation of nitrogenous heterocyclic compounds (uracil, barbituric acid, iso-dialuric acid, dialuric acid and hydantoin) as examined for the oxidation products in aqueous solution (pH 3–8). It has been demonstrated in all cases that the oxidative attack takes place on C5 or C6 while, depending on the pH, stable six-ring compounds, such as alloxan, five-ring compounds, such as parabanic acid and alloxanic acid, as well as ring-opening products, such as formyloxaluric acid, oxaluric acid and formic acid are formed. In some cases, hydrogen peroxide was detected as the inorganic product. The oxidation of hydantoin causes a quantitative production of parabanic acid in acid solution, whereas at pH 7 ring-opening takes place and oxaluric acid has been detected as the product of oxidation. From the carbon balances made it can be assumed that more than 90% of the products have been detected.