稻壳基活性炭的制备及其对亚甲基蓝吸附的研究

Study on preparation of rice husk-based activated carbon and its adsorption of methylene blue

以稻壳为原料,采用K2CO3活化法和H3PO4活化法制备了比表面积为1 312 m2/g和682 m2/g的活性炭,通过扫描电子显微镜(SEM)、X-射线衍射仪(XRD)对样品进行了表征,并将孔隙发达的活性炭样品用于对亚甲基蓝的吸附,结果表明,K2CO3活化法制备的活性炭样品具有更多的微孔结构;随着亚甲基蓝溶液初始浓度的增加、活性炭吸附时间的延长,亚甲基蓝的去除率呈现逐渐降低和逐渐增大的变化规律,当pH值为6时,活性炭对亚甲基蓝的吸附效果最佳;稻壳基活性炭对亚甲基蓝的吸附等温线符合Langmuir模型,Qm最高可达476.2 mg/g;热力学参数ΔG0、ΔH0和ΔS0均为负值,表明稻壳基活性炭对亚甲基蓝的吸附是一个自发的放热反应。

Activated carbon was prepared from rice husk by using K2COs and H3PO4 , and the two types of activated carbon prepared by these two chemicals have specific surface areas of 1 312 m^2/g and 682 m^2/g respectively. Activated carbon with developed pore structures was used to adsorb methylene blue after being characterized by scanning electron microscope（SEM） and X-ray diffraction（XRD）. Results show that the activated carbon prepared by K2CO3 activation has more microporous structures. The removal rate of methylene blue de- creases with increasing initial concentration of methylene blue. Meanwhile, the removal rate increases with increasing adsorption time. The best adsorption effect can be obtained at pH 6. Adsorption isotherm of methylene blue is best fitted with Langmuir model, and its Qm value can reach up to 476.2 mg/g. Thermodynamic parameters such as △G^0△H^0 and △S^0 are negative, which show that the adsorption of methylene blue by rice huskbased activated carbon is a spontaneous and exothermic reaction.