碳酸氢钾活化制备水稻秸秆炭孔结构的影响因素及吸附性能

Investigation on the influencing factors of pore structure on rice straw activated carbon with KHCO_3 and its adsorption ability

以水稻秸秆为原料,KHCO_3为活化剂,制备水稻秸秆基活性炭.采用L_9(3~3)_3因素3水平正交实验,探讨制备的实验方案与工艺条件;分析了浸渍比、活化温度、活化时间在3个不同水平下,对水稻秸秆基微孔、中孔活性炭形成的影响.结果表明,活化温度对中孔的形成影响最大,浸渍比对微孔的形成影响最大;活化温度900℃、活化时间1.5 h、浸渍比1∶6的工艺条件适宜中孔的形成,活化温度800℃、活化时间0.5 h、浸渍比1∶6的工艺条件适宜微孔的形成.亚甲基蓝吸附实验表明,水稻秸秆基活性炭对亚甲基蓝的吸附主要受中孔孔容大小影响;Redlich-Peterson方程能较好地描述等温吸附行为,既有单分子层吸附,也有多分子层吸附.

Rice straw-based activated carbons were prepared with rice straw as raw material by KHCO_3 activation. A L_9（ 3~3）（ three three-level factors） orthogonal design table was established to investigate the influences of KHCO_3 ratio, activation temperature and activation time on the microporous and mesoporous structures of the activated carbons. The experimental results show that the most important factor on the formation of mesopore is the activation temperature,while the most important factor on the formation of micropore is the KHCO_3 dose. The optimal conditions of forming mesopore are as follow： 1∶6 of KHCO_3 ratio,90 minutes of activation time and 900 ℃ of activation temperature. The optimal conditions of forming micropore are as follow： 1∶ 6 ratio of stalk： KHCO3,30 minutes of activation time and 800 ℃ of activation temperature. The experimental results of methylene blue adsorption show that the most important factor methylene blue adsorption was the size of mesoporous volume. Adsorption isotherm of methylene blue is best fitted with Redlich-Peterson model,which shows the that it not only has mono layer adsorption but also has multimolecular layer adsorption.