采用热重分析仪(TG-DTG)分析了 NH4 H2 PO4活化甘蔗叶时的热解历程和活化反应机理,研究了活化剂浓度、液料比、浸泡时间、活化温度及活化时间等工艺因素对甘蔗叶活性炭样品得率、碘吸附值的影响,并运用扫描电子显微镜(SEM)对甘蔗叶及其活性炭样品进行了表征.结果表明,甘蔗叶制备活性炭的反应为4C＋2NH4 H2 PO4→P2 O3＋CH4↑＋CO2↑＋2CO↑＋2NH3↑＋H2 O↑甘蔗叶活性炭的碘吸附值随着活化时间的延长而增加,随着活化剂浓度、液料比、浸泡时间、活化温度的增加而呈现先增后减的变化规律；甘蔗叶活性炭的最优制备工艺条件为活化剂浓度2．5％(质量分数),液料比为5∶1,浸泡时间为20 h,活化温度为700℃,活化时间为60 min,所制备的活性炭样品具有丰富的管束结构,其得率和碘吸附值分别为30．9％、993．33 mg/g.
The pyrolysis reactions of sugarcane leaves activated by NH4 H2 PO4 were carried out using the ther-mo-gravimetric analyzer to analysis the pyrolysis mechanism,the influencing factors on the yield and adsorption capacity of the activated carbon such as activator concentration,the ratio of activator solution to sugarcane leav-es,soaking time,activating temperature and time were systematically investigated,and the microstructure of samples was characterized by means of scanning electron microscope(SEM).The results show that the activa-tion mechanism of sugarcane leaves was as follow:4C+2NH4 H2 PO4→P2 O3+CH4↑+CO2↑+2CO↑+ 2NH3↑+H2 O↑The iodine adsorption value of the samples would increase with prolong the activation time,and increase first and then decrease with the increase of activator concentration,the ratio of activator solution to sugarcane leaves,soaking time or activation temperature.The suitable preparation conditions was as follows:sugarcane leaves was infused 20 h in 2.5wt% ammonium dihydrogen phosphate with the ratio of activator solution to sug-arcane leaves 5∶1,and treated 60 min at 700 ℃,the sugarcane leaves-based activated carbon has abundant por-ous microstructures,and the yield and iodine adsorption value of the specimen were 29.33% and 987.69 mg/g, respectively.
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