摘要
用不同浓度的硝酸(NNO_3)和过二硫酸按((NH_4)_2S_2O_8)对煤基活性炭和椰壳活性炭进行了氧化改性,并用N_2吸附、Beohm's滴定、质量滴定和FT-IR进行了表面性质表征.实验结果表明,高浓度HNO_3处理使表面积和孔体积降低,表明强氧化的生成物堵塞细孔,而低浓度HNO_3的处理使表面和孔容有所增加,表明有氧化腐蚀打通封闭的细小微孔.值得注意的现象是(NH_4)_2S_2O_8的氧化改变了煤基炭的微孔孔径分布,但却对椰壳炭的微孔孔径分布几乎没有影响,这可能是酸性氧化溶解了煤基炭的灰分使孔隙结构发生改变.Beohm's滴定发现HNO_3氧化使表面羧基增加明显而(NH_4)_2S_2O_8氧化使表面酚羟基和内酯基含氧基团增加较多并由FT-IR图谱得以证实.质量滴定和Beohm's滴定结果表明通过测定PZC值可方便指示出表面的酸碱性.
Coal-base carbon and coconut shell carbon were chemically modified by oxidation with different concentration of nitric acid and ammonium peroxydisulfate. These carbons were characterized by using different techniques, such as N2 adsorption, the Beohm's titration, mass titration and FTIR. Results showed that, with high concentration HNO3 treatment, the surface area and pore volume of carbon decreased, for the strong oxidation probably obstructed the entrance of micropore. Contrastively, with the low concentration HNO3 treatment, the surface area and pore volume of carbon increased, which suggested that the modest oxidizing corrosion opened up the enclosed tiny hole. A interesting phenomena is that (NH4)2S2O8 treatment affected micorpore structure of coal-base carbon but little influenced on micropore structure of coconut shell carbon, because the acidic oxidant dissolved ash in coal-base AC and changed its porosity. Generally (NH4)2S2O8 treatment greatly increased surface lactones and phenolic groups, whereas nitric acid oxidation produced a greater amount of carboxyl groups, as detected by FT-IR. The result of Boehm's titration and mass titration indicated the PZC can be used as a convenient index for correlating changes in surface acidity of carbon.
出处
《中国矿业大学学报》
EI
CAS
CSCD
北大核心
2003年第6期729-733,共5页
Journal of China University of Mining & Technology
