氯化锌-水蒸气协同活化玉米芯制活性炭的研究

Study on preparation of activated carbon from corn cob by zinc chloride and water vapor

以宁夏农业废弃物玉米芯为原料,制备对亚甲基蓝(MB)吸附性能最优条件下的氯化锌活性炭(ZnAC),并在此条件基础上利用氯化锌-水蒸气来协同活化制备不同活化温度下的活性炭(ZnHAC)。利用BET、XRD、FT-IR和SEM分析ZnAC和ZnHAC的结构和表面特性,阐释活化机理。结果表明:ZnCl_(2)单独活化玉米芯的最佳条件为活化温度为500℃、活化时间为1 h、锌料质量比为1.5∶1;所制活性炭的比表面积为2299.75 m^(2)/g,累积总孔容为1.28 cm^(3)/g,对MB吸附量为531.56 mg/g;此活性炭介孔率高达95%以上,且随着温度的升高,介孔率都有所增加,说明提高温度有利于介孔的形成。相对于ZnAC_(T-1.5-1),通入水蒸气之后ZnHAC_(T-1.5-1)的比表面积和孔容都有明显增大,其中ZnHAC_(800-1.5-1)的比表面积比ZnAC_(800-1.5-1)增加了349 m^(2)/g,而介孔孔容、总孔容及孔径近乎增加1倍,ZnHAC_(800-1.5-1)活性炭表面含有更丰富的无定型碳。水蒸气的通入丰富了活性炭的结构,增加了活性炭表面的含氧官能团,提高了炭结构的无序化程度,使活化效果更为显著。

Zinc chloride activated carbon(ZnAC)with optimal methylene blue(MB)adsorption performance was prepared from corn cob of Ningxia agricultural waste.Based on these conditions,zinc chloride and water vapor were used to prepare activated carbon(ZnHAC)at different activation temperatures.The structure and surface properties of ZnAC and ZnHAC were analyzed by BET,XRD,FT-IR,and SEM to elucidate the activation mechanism.The results showed that the optimum conditions for ZnCl2 activation were temperature of 500℃,activation time of 1 h,and zinc feed mass ratio of 1.5∶1.The specific surface area of activated carbon was 2299.75 m^(2)/g,the cumulative pore volume was 1.28 cm3/g,and the adsorption capacity of MB was 531.56 mg/g.The mesoporous rate of the activated carbon was up to more than 95%,and the mesoporous rate was increased with the increase in temperature,indicating that increasing temperature was conducive to the formation of mesoporous.At the same temperature,compared with ZnACT-1.5-1,the specific surface area and pore volume of ZnHACT-1.5-1 increased significantly after water vapor was introduced,and the specific surface area of ZnHAC_(800-1.5-1)was increased by 349 m2/g compared with ZnAC_(800-1.5-1),and mesoporous pore volume,total pore volume,and pore size were nearly doubled,respectively.ZnHAC_(800-1.5-1)activated carbon surface contained more amorphous carbon.The activation effect of water vapor at high temperatures was more pronounced.The vapor made the activation effect more significant,because of enriching the structure of activated carbon and the oxygen-containing functional groups on the surface of activated carbon,and increasing of the disordered degree of carbon structure.