One pot non-emulsion based hydrothermal synthesis of urchin-shaped hydroxy sodalite using waste coal fly ash

Abstract

Urchin-shaped hydroxy sodalite particles have been synthesized by one pot non-emulsion based hydrothermal conversion of coal fly ash at 100 °C for 96 h in the absence of any surfactants. Crystallization behavior of the particles has been studied by X-ray diffraction, and the characteristic vibration bands of hydroxy sodalite were confirmed by FTIR spectroscopy. BET surface area of the particles are found to be 193, 197, 82 and 44 m² g^-1 for the reaction time of 24 h, 48 h, 72 h and 96 h, respectively. FESEM images revealed that the thread-ball-like particles are converted into urchin-shaped hydroxy sodalite with increasing reaction time from 24 h to 96 h at 100 °C. The elemental analysis of the product studied by EDX indicates the Si/Al and Na/Al ratios of 1.28 and 1.03, respectively which is close to the stoichiometric composition of hydroxy sodalite.