氯化锌活化生物质炭制备活性炭及其表征

Preparation and characterization of activated carbon from bio-char by chemical activation with ZnCl_2

以生物质炭为原料,采用氯化锌活化制备高比表面积微孔生物质活性炭,研究了浸渍比、活化剂浓度、活化温度与活化时间等条件对生物质活性炭吸附性能的影响,利用氮气吸附脱附、扫描电子显微镜、傅里叶红外光谱、X射线衍射等技术对生物质活性炭表面微观结构、形貌特征及化学结构进行了分析。结果表明,制备生物质活性炭的适宜工艺条件为:浸渍比为3,活化剂质量分数为40%,活化温度为600℃,活化时间为90min。在该条件下制备的生物质活性炭对亚甲基蓝的吸附值为213mg/g,超过国家水处理用活性炭一级品标准。经测试生物质活性炭的BET比表面积高达631.2m2/g,平均孔径2.23nm,总孔容为0.352cm3/g;孔隙结构发达,孔径分布狭窄,孔形状为排列整齐的蜂窝状结构,含有大量的微孔,84.4%的孔集中在2nm以内;表面存在醇羟基、羰基、醚、酚等含氧官能团。

High surface area activated carbons were prepared with bio-char as raw material and ZnCl2 as activating agent. Effects of impregnation ratio,activator concentration,activation temperature,and activation time on the adsorptive capacity of activated carbon were studied. The properties and pore structure of the carbon were characterized with nitrogen adsorption-desorption,scanning electron microscopy （SEM）,infrared spectroscopy （FT-IR）,power X-ray diffractometry （XRD）. The suitable preparation condition was obtained as follows：impregnation ratio of 3,activator concentration of 40%, activation temperature of 600℃and activation time of 90min. The results show that the methylene blue adsorption on activated carbon,which was obtained under above condition,reaches to 213mg/g,which was much higher than the national first level for activated carbon. The activated carbon has a large apparent surface area （SBET=631.2m^2/g）,relatively concentrated pore （2nm pore is more than 84.4%） and high adsorption power volume （V=0.352cm^3/g）.