The thermodynamics and kinetics for the removal of copper and nickel ions by the zeolite Y synthesized from fly ash

In this paper, zeolite was synthesized from Class C fly ash (FA) using the fusion-hydrothermal method, and characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM) and Brunauer–Emmett–Teller (BET) analyzer. The results show the synthetic zeolite belongs to zeolite Y with high purity, eight crystal surfaces and a specific surface area of about 389.4 m² g⁻¹. Meanwhile, the thermodynamic and kinetic behaviors of copper and nickel ions removed by the products were explored. The Langmuir model can well describe the isothermal curves of Cu (II) and Ni (II), and increasing temperature is beneficial to the improvement of equilibrium adsorption capacity. Dubinin-Radushkevich (DR) isothermal model indicates that the removal process of Cu (II) and Ni (II) belongs to ion-exchange. The Freundlich model parameter of n shows the removal of Cu (II) and Ni (II) is easy. Pseudo nth-order kinetics (PK) and nth-order reaction kinetics (RK) both can well match the kinetic experimental data, and the mean relative errors between the experimental data and the model values are 2.79% for Cu (II) and 5.65% for Ni (II) respectively, and the kinetic models for the removal of copper and nickel ions by the synthetic zeolite were successfully established by global nonlinear optimization technique. The synthetic zeolite Y has excellent removal ability of copper and nickel ions. (paper)