KOH改性石墨烯对甲苯的吸附动力学及吸附机制

Adsorption kinetics and mechanism of toluene on KOH modified graphene

关键词:  改性石墨烯  氢氧化钾  甲苯  吸附动力学

Key words:  modified graphene  KOH  toluene  adsorption kinetics

摘要:

以改进Hummer 's法制备石墨烯,再经超声辅助KOH浸渍法制备改性石墨烯(MGE)材料,并采用TEM、XRD、N₂吸-脱附、FT-IR光谱对材料的形貌结构、官能团、孔径、孔容进行表征。考察不同浓度KOH、超声时间、温度条件下制备的改性石墨烯甲苯性能,分析吸附动力学和吸附机制。结果表明:石墨烯和改性石墨烯的比表面积分别为427.72和439.24 m²/g;在一定条件下,甲苯饱和吸附率与超声时间、温度呈正相关关系,并随KOH浓度的增加先增后减;在实验温度为25 ℃、甲苯质量浓度为1.3 g/m³,吸附剂质量为0.3 g条件下,经6 mol/L KOH、3 h超声处理制备的改性石墨烯对甲苯的饱和吸附率为212.75×10-3;吸附过程符合准二级吸附动力学模型;吸附机制为孔道填充、疏水性作用、π-π键作用和H键作用。

Abstract:

Graphene was prepared by improved Hummer 's method, then modified graphene (MGE) was prepared by ultrasound-assisted impregnation with KOH. The morphology, functional groups, pore size and pore volume of the materials were characterized by TEM, XRD, N₂ adsorption-desorption and FT-IR spectroscopy, respectively. Meanwhile, the influences of different the concentrations of KOH, ultrasonic time, temperature condition on the adsorption of toluene on the properties of the modified graphene were investigated to analyze the adsorption kinetics and mechanism. The results show that the specific surface area of graphene and modified graphene are 427.72 m²/g and 439.24 m²/g, respectively. Under certain conditions, the saturated adsorption capacity of toluene is positively correlated with the ultrasonic time and temperature. However, with the increase of KOH concentration, it increases first and then decreases. At the temperature of 25 ℃, the toluene concentration of 1300 mg/m³ and the adsorbent mass of 0.3 g, the saturated adsorption capacity of modified graphene to toluene prepared by 6 mol/L KOH and 3 h ultrasonic treatment is 212.75×10-3. The adsorption process fits the pseudo-second-order adsorption kinetics model. The adsorption mechanisms are pore filling, hydrophobic interaction, π-π interaction and hydrogen bonding.