Adsorption kinetics and mechanism of toluene on KOH modified graphene

Key words:  modified graphene  KOH  toluene  adsorption kinetics

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.