磷酸法玉米秸秆基活性炭的制备及其表征

Preparation and Characterization of Corn Straw Based Activated Carbon by Phosphoric Acid Activation

以成型、烘焙处理后的玉米秸秆为原料,磷酸作为活化剂制备了玉米秸秆基活性炭,并对活性炭样品进行表征。同时以碘吸附值、亚甲基蓝吸附值和焦糖脱色率为指标测定其吸附性能,并对制备条件进行优化。实验结果表明:玉米秸秆制备活性炭的最佳工艺条件为浸渍比即m(55%H_(3)PO_(4))∶m(玉米秸秆)为4∶1、活化温度400℃、活化时间100 min,此条件下活性炭的得率为47.78%,制得的活性炭具有良好的吸附性能,碘吸附值、亚甲基蓝吸附值及焦糖脱色率分别达到864 mg/g、210 mg/g和100%。活性炭比表面积可达1105 m^(2)/g,总孔容积为0.745 cm^(3)/g,微孔孔容为0.287 cm^(3)/g,中孔孔容为0.354 cm^(3)/g,孔径分布集中于5 nm以内,约占73.56%,平均孔径为2.697 nm。FT-IR分析显示:在活化过程中磷酸与玉米秸秆发生交联作用,生成的活性炭损失了玉米秸秆的部分官能团。

Corn straw based activated carbon was prepared from corn straw after formed and torrefied by H_(3)PO_(4) activation and characterized by N2 adsorption,elemental analysis and FT-IR.The results showed that the optimal conditions were the impregnated ratio of 4∶1,the activation temperature of 400℃and the activation time of 100 min.Under these conditions,the yield of activated carbon was 47.78%and the activated carbon showed excellent adsorption capacity with the iodine adsorption value of 864 mg/g,the methylene blue adsorption of 210 mg/g and the caramel decolorization of 100%.The specific surface area and the total volume of activated carbon reached 1105 m^(2)/g and 0.745 cm^(3)/g,the micropore volume was 0.287 cm^(3)/g,the mesopore volume was 0.354 cm^(3)/g.Meanwhile,the distribution of pore was concentrated within 5 nm,accounting for 73.56%,and the average pore diameter is 2.697 nm.The FT-IR results showed that the crosslinking reaction was occured between H3PO4 and corn straw during octivation and the activated carbon lost some functional groups of corn straw.