Cycling system for decomposition of gaseous benzene by hydrogen peroxide with naturally Fe-containing activated carbon

Abstract

For the removal of volatile organic compounds (VOCs) from environmental systems, gaseous benzene, a model VOC, was adsorbed on naturally Fe-containing activated carbon and subsequently, decomposed in the presence of de-ionized water, and low (0.03%, pH 6.5) and high (30%, pH 2.5) concentration H₂O₂ solutions. The intermediates produced during benzene decomposition were analyzed and compared using gas chromatography-mass spectrometry. After the decomposition process, the activated carbon sample was air dried. Three cycles were carried out with de-ionized water and low and high concentration H₂O₂ solutions as oxidants. The adsorption capacity of the activated carbon sample treated with DI water gradually decreased as the number of cycles increased. On the other hand, the benzene adsorption capacity of the activated carbon samples treated with the H₂O₂ solutions was improved due to the relatively higher specific surface areas of these samples. After treatment with the low-concentration H₂O₂ solution, intermediates such as glyoxylic acid, oxalic acid, phenol, malonic acid, and pyrocatechol were observed. After treatment with high-concentration H₂O₂ solution, intermediates such as glyoxylic acid, formic acid, and acetic acid were formed. With increasing H₂O₂ concentration, the number and the molecular weight of the intermediate formed by the oxidative degradation of benzene, simultaneously decreased. The Fenton reaction induced by naturally Fe-containing activated carbon and H₂O₂ could lead to more efficient decomposition of benzene.