Synthesis of ZSM-5 zeolite from fly ash and its adsorption of phenol, quinoline and indole in aqueous solution

Abstract

This work tries to synthesize ZSM-5 zeolite using fly ash (FA) by hydrothermal method and study the adsorption effect of the zeolite on phenol, quinoline and indole in aqueous solution. The zeolites were characterized with x-ray diffraction (XRD), scanning electron microscopy (SEM), x-ray fluorescence (XRF), fourier transformation infrared (FTIR) and N2 adsorption-desorption isotherm. The characterization results showed that HZSM-5 zeolite was successfully synthesized. The higher mass ratio of sodium carbonate to fly ash during melting is beneficial to improve the purity of ZSM-5 zeolite and its removal rate of organic matters. These results have been confirmed by XRD and principal component analysis (PCA). The adsorption process of phenol, quinoline and indole in aqueous can be well described with the double exponential kinetic model. The adsorption capacity of ZSM-5 zeolite for phenol, quinoline and indoles can be up to 24.41 mg g−1, 35.99 mg l−1 and 34.05 mg g−1 respectively, and the removal rates can reach up to 82.80%, 84.86% and 83.20% respectively. The optimal pH value for adsorption ranges from 5 to 7.