水热法制备玉米叶基生物炭对亚甲基蓝的吸附性能研究

以农业废弃物玉米叶和玉米秆为原材料,采用水热法制备生物炭,通过批试验方法考察了接触时间、污染物初始浓度、生物炭投加量、反应体系温度及溶液p H值等因素对2种生物炭吸附亚甲基蓝的影响,并对吸附规律进行了探讨.吸附动力学拟合结果发现,准二级动力学能更好地拟合吸附过程(R~2=0.9986~0.9999);颗粒内扩散方程拟合结果表明,2种生物炭对亚甲基蓝的吸附由液膜扩散和颗粒内扩散2个过程控制.玉米叶基生物炭对亚甲基蓝的吸附可以通过Freundlich方程来进行拟合(R~2=0.9898),说明吸附在生物炭表面是多分子层吸附过程;而玉米杆基生物炭对亚甲基蓝的吸附更符合Langmuir方程(R~2=0.9825),说明吸附在生物炭表面是单分子层吸附过程.与玉米杆基生物炭相比,玉米叶基生物炭具有更好的吸附性能,拟合理论最大吸附量为玉米杆基生物炭的1.25倍.

Hydrothermal preparation of maize leaf based biochar and its adsorption performance for methylene blue

Maize leaf and maize straw were used as the raw materials to prepare the biochars through hydrothermal method. The effects of various parameters such as contact time, initial concentration of pollutants, adsorbent dosage, temperature and solution pH value on the adsorption of methylene blue were investigated. The kinetic data showed that it was fitted well with the pseudo-second order model (R²=0.9986~0.9999). Intraparticle diffusion model indicated that adsorption process was influenced by both liquid film and intraparticle diffusion. The adsorption data of maize leaf based biochar were well fitted with Freundlich model (R²=0.9898), indicating that the adsorption of methylene blue was multilayer process. However, the adsorption data of maize straw based biochar were fitted with the langmuir model (R²=0.9825), suggesting that the adsorption of methylene blue was monolayer molecule sorption. Compared with maize straw based biochar, maize leaf based biochar exhibited better adsorption capacity and the maximum adsorption capacity calculated from langmuir model was 1.25 times higher than that of the maize straw based one.