Leaching of coal fly ash with sulphuric acid for synthesis of wastewater treatment composite coagulant

Abstract

ABSTRACT The results of leaching of coal fly ash in H2SO4 solution are presented. The effects of leaching time, H2SO4 concentration, temperature, and solid/liquid ratio were explored for the dissolution process. Particle size distribution results showed that changes in particle size occurred during the dissolution process; XRD, XRF and FTIR results indicated the same characteristics of the mineral matter in the raw and treated coal fly ash samples; and SEM showed that the raw coal fly ash particles have smooth spherical surfaces while a pricked and corroded surface and a stem-like structure were formed after leaching. The dissolution rate of coal fly ash is controlled by mixed-controlled mechanism (diffusion and chemical reaction). The corresponding activation energies were calculated to be 59.8 kJ/mol for iron, 7.3 kJ/mol for aluminium and 5.8 kJ/mol for silicon. The reaction order was determined to be zero order kinetic model.