富含中孔与酸性基团的生物质炭的制备与吸附性能

Preparation,Characterization and Adsorption Performance of Mesoporous Activated Carbon with Acidic Groups

以棉秆基生物质纤维为原料,采用磷酸一步活化法制备了同时富含中孔与含氧酸官能团的新型高比表面棉秆纤维基生物质活性炭,分析了浸渍比、炭化温度及保温时间等操作参数对活性炭纤维组成、得率、孔结构及表面官能团含量的影响,测定了制得的棉秆纤维基活性炭对水中对Pb(Ⅱ)与对硝基苯胺的等温吸附性能,并初步探讨了其吸附机制.结果表明,棉秆纤维基生物质炭孔结构与含氧酸基团因制备条件不同有较大变化,实验条件下制备的棉秆基活性炭纤维产率、中孔孔容与比表面的最大值分别为35.5%、0.91 cm3·g-1、1731 m2·g-1;在3∶2的浸渍比,600℃活化90 min的工艺条件下,制备的样品ACF-01的总孔孔容达1.02 cm3·g-1,比表面积为1 731 m2·g-1,微、中孔比例分别为66%与31%,中孔集中在5 nm以内,富含含氧酸官能团.样品ACF-01对水中Pb(Ⅱ)与对硝基苯胺的Langmuir最大吸附量分别为123 mg·g-1和427 mg·g-1,吸附性能远高于微孔孔容相近的商业活性炭纤维ACF-CK,这表明活性炭ACF-01的中孔和含氧酸官能团在吸附过程中发挥了重要作用.

Mesoporous activated carbons containing acidic groups were prepared with cotton stalk based fiber as raw materials and H3PO4 as activating agent by one step carbonization method.Effects of impregnation ratio,carbonization temperature and heat preservation time on the yield,elemental composition,oxygen-containing acid functional groups and adsorptive capacity of activated carbon were studied.The adsorption capacity of the prepared activated carbon AC-01 for p-nitroaniline and Pb（Ⅱ） was studied,and the adsorption mechanism was also suggested according to the equilibrium experimental results.The maximum yield of activated carbons prepared from cotton stalk fiber reached 35.5% when the maximum mesoporous volume and BET surface area were 1.39 cm3.g-1 and 1 731 m2.g-1,respectively.The activated carbon AC-01 prepared under a H3PO4/ precursor ratio of 3∶ 2 and activated at 900℃ for 90 min had a total pore volume of 1.02 cm3.g-1,a micoporous ratio of 31%,and a mesoporous ratio of 65%.The pore diameter of the mesoporous activated carbon was mainly distributed in the range of 2-5 nm.The Langmuir maximum adsorption capacities of Pb（Ⅱ） and p-nitroaniline on cotton stalk fiber activated carbon were 123 mg·g-1 and 427 mg·g-1,respectively,which were both higher than those for commercial activated carbon fiber ACF-CK.The equilibrium adsorption experimental data showed that mesopore and oxygencontaining acid functional groups played an important role in the adsorption.