硝酸表面氧化改性木质活性碳纤维

采用2~14mol/L的硝酸,在23~83℃下,对木质活性碳纤维(WACF)浸渍氧化改性1~8h后,通过Raman、XPS、水吸附和汞吸附等表征表面官能团的结构性能。结果表明,硝酸氧化能力强,可以增加氧原子浓度。酚基、醇基、羟基、羧基官能团随着硝酸浓度增大而增多,酚基和醇基随着浸渍时间的延长而减少,羟基随着浸渍时间的延长而显著增多。WACF表面的石墨化程度随硝酸浓度增大而提高,芯部石墨化程度整体提高但不随浓度梯度的变化而变化。硝酸改性后WACF的水吸附孔容降低,水吸附比表面积显著增加。WACF对HgCl2的吸附量随着硝酸浓度的增大、温度的升高和浸渍时间的延长而增大。以WACF的吸附能力为研究目标,通过对其形貌、晶体结构、表面官能团等进行表征,揭示影响水吸附、汞吸附性能的表面结构特性和化学特性的内在规律,研究结果对WACF功能化利用有指导意义。

Surface Oxidation Modification of Wooden Activated Carbon Fibers with Nitric Acid

The surface oxidation of wooden activated carbon fibers (WACF)by nitric acid can increase the content of oxygen-containing functional groups and contribute to the functional utilization of WACF.Samples were treated with different nitric acid con-centration,temperature and soaking time,and then the performance characteristics were characterized by Raman,XPS,water ad-sorption and mercury adsorption.The results showed the enhancement of nitric acid oxidation increased the proportion of oxygen atoms.The content of phenol and alcohol functional groups rose with the increase of nitric acid concentration,and reduced with the increase of soaking time.The content of hydroxyl group increased significantly with the increase of soaking time.The graphitization degree on the surface of WACF rose with the increase of nitric acid concentration,and the graphitization degree in the core increased as a whole,but it was not affected by the concentration gradient.The water adsorption pore volume of WACF decreased and the spe-cific surface area of water adsorption rose remarkably after nitric acid modification.The adsorption amount of WACF on HgCl2 grew with the increase of nitric acid concentration,temperature and oxidation time.On the basis of the adsorption capacity of WACF,the internal rules of surface structure and chemical properties of water adsorption and mercury adsorption are revealed through the cha-racterization of morphology,crystal structure and surface functional groups,which have significant guidance for the functional utilization of WACF.