Synthesis and Characterization of Zeolite X Obtained from Coal Gangue for Adsorption of Cu2+

Abstract

China is a big coal producing country, there are a lot of coal gangue piled up. The zeolite X was synthesized by alkali melting and hydrothermal method based on the coal gangue from Chifeng city, Inner Mongolia. The obtained zeolite X sample is characterized by X-ray diffraction, SEM, EDS spectrum and IR which showed the X zeolite is an octahedral structure with complete crystal shape and uniform grain size. The results of BET showed the specific surface area of zeolite X is 354.8 m2/g and the minimum pore size is 3.8 nm which indicated that the zeolite X belongs to mesoporous materials. The adsorption conditions of the zeolite X adsorbent on copper ions were optimized. A solution containing Cu2+ ions with an initial concentration of 300 mg/L was added to the zeolite X with a dosage of 0.1 g and the initial pH value of the solution was adjusted to 6. Then the solution was oscillated for 120 min at 225 r/min. The maximum adsorption capacity and removal rate were 148.6 mg/g and 99.1%, respectively. The adsorption mechanism was discussed by adsorption kinetics and thermodynamics. The quasi-second order kinetic equation can be well used to describe the adsorption kinetics of zeolite X to Cu2+ (R2 = 0.9994) and Langmuir can well describe the adsorption behavior of zeolite X to Cu2+ (R2 = 0.9995) which showed the adsorption is a monolayer of chemical adsorption. The adsorption capacity of zeolite X to Cu2+ is about 4.0 times that of coal gangue, indicating that the zeolite X has good adsorption capacity.