活性炭孔结构和表面官能团对吸附甲醛性能影响

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

通过对不同比表面积和孔结构的活性炭进行甲醛吸附的研究,以重量法精确测量活性炭对甲醛气体的饱和吸附量,比较各种活性炭和改性活性炭的吸附效果。实验表明,活性炭对甲醛分子的吸附与其孔结构和表面官能团密切相关,微孔比表面积大吸附效果明显,中孔比表面积大达到吸附平衡的时间短。此外,通过对活性炭浸渍改性的研究表明,强氧化性的HNO3和H2O2处理的样品均有利于对甲醛分子的吸附,而氨基改性过的样品吸附效果减弱,主要原因是HNO3改性增加了活性炭表面的CO、O—CO等含氧官能团的量,从而改善了对甲醛的吸附效果。

Adsorption of formaldehyde on activated carbon with different surface area and microspere 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.