Simultaneous removal of Cd(II), Co(II), Cu(II), Pb(II), and Zn(II) ions from aqueous solutions via adsorption on fau-type zeolites prepared from coal fly ash

Abstract This study reports the potential for the simultaneous removal of Cd(II), Co(II), Cu(II), Pb(II), and Zn(II) ions from aqueous solutions by FAU-type zeolites prepared from coal fly ash. The zeolite synthesis route was via alkaline fusion followed by the addition of deionised water and hydrothermal treatment using fly ash to water mass ratios of 4, 10, 15, and 20. XRD, XRF, SEM and N2 adsorption measurements were used to characterize the prepared zeolites. Adsorption experiments were carried out for variations in concentration, time, and adsorbent loading. The adsorption process followed pseudo second-order kinetics and Langmuir adsorption isotherm; intra particle diffusion model fitting indicated that diffusion within the pores affected the rate controlling steps and mass transfer across boundary layers for the adsorbate – adsorbent system. The efficacy of FAU – type zeolite for the quinary-metal ions adsorption studied decreased in the order Pb(II) > Cu(II) > Cd(II) > Zn(II) > Co(II).