Adsorption of mercuric ion from aqueous solutions using modified fly ash

Abstract

In this study, fly ash was treated with NaOH solution (FA-NaOH) before modifying with (3-mercaptopropyl) triethoxysilane - MPS (FA-MPS). By using Fourier transforms infrared spectroscopy (FTIR), Field emission scanning electron microscopy (FESEM), Energy-dispersive X-ray spectroscopy (EDX) and Brunauer - Emmett - Teller (BET) nitrogen adsorption methods and techniques, the change in structure, composition and morphology of FA-NaOH and FA­MPS was evaluated. The FTIR spectra of FA-NaOH and FA-MPS showed that there is no chemical reaction between the MPS and FA-NaOH. After modification, the FA-MPS has a rough surface with composition difference from the FA-NaOH. Mercuric ion adsorption behavior of the FA-NaOH and FA-MPS were investigated. Thanks to FA-NaOH modification, the mercuric ion removal percent of the FA-MPS was higher than that of the FA-NaOH. The value of the mercuric ion removal percent of the FA-MPS reached 45.20 % to 62.57 % while that of FA-NaOH is 40.50 %. Besides, adsorption isotherm models (according to Langmuir and Freundlich isotherms) of the FA-NaOH and FA-MPS were also discussed.