EFFECTS OF MICROPORE AND FUNCTIONAL GROUPS OF ACTIVATED CARBON ON ADSORPTION BEHAVIOR OF FORMALDEHYDE

Adsorption of formaldehyde on activated carbon with different surface area and microspore volume was investigated, the saturated adsorption capacity of formaldehyde of the activated carbon was accurately measured by the gravity method and the adsorption effect between the activated carbons and modified activated carbons was compared. It was found that the adsorption capacity of formaldehyde was related with the micropore surface area and functional groups of the surface of activated carbon. As the micropore surface of activated carbon increased, the adsorption capacity of formaldehyde increased, and mesopore surface is only correlated to the time of adsorption equilibrium. In addition, the X-ray photoelectron spectroscopy (XPS) was applied to the activated carbon modified by nitric acid, hydrogen peroxide and ammonium solution, respectively. The compositions of elements contained as well as the types of surface groups on activated carbon were studied. Results show that the activated carbon modified by nitric acid and hydrogen peroxide had the better capacity of formaldehyde, while the one modified by ammonium solution deceased. It can be concluded from the XPS measurement that the increased contents of C O and O— C O groups effect the adsorption ability of formaldehyde.