Chemical modification of coal fly ash into iodate sodalite and its use for the removal of Cd2+, Pb2+, and Zn2+ from their aqueous solutions

• Published in: Desalination and water treatment 2012-12, Vol.50 (1-3), p.157-169
• Main Authors: Borhade, Ashok V., Dholi, Arun G., Wakchaure, Sanjay G., Tope, Dipak R.
• Format: Article
• Language: English
• Subjects: Adsorption; Applied sciences; Exact sciences and technology; Fly ash; Freundlich isotherm; Heavy metals; Hydrothermal; Iodate sodalite; Langmuir isotherm; Pollution; Water treatment and pollution
• ISSN: 1944-3986; 1944-3994; 1944-3986
• DOI: 10.1080/19443994.2012.708564

This study investigated the chemical modification of F-class coal fly ash (CFA) to an iodate enclathrated aluminosilicate sodalite, Na8[AlSiO4]6(IO3)2, cubic P4¯3n, has been synthesized by hydrothermal treatment followed by fusion of CFA with NaOH. The fused mass was mixed with excess NaIO3 and hydrothermally treated at 100°C. Infrared spectroscopy, X-ray diffraction, Scanning electron microscopy, and inductively coupled plasma spectroscopy methods were used to characterize the obtained sodalite. Sorption behavior of heavy metals (Cd2+, Pb2+, and Zn2+) from aqueous solution on iodate sodalite was examined. The Freundlich and Langmuir isotherms are evaluated for iodate sodalite. These models were fitted to the curves of heavy metals ion solutions to estimate the Freundlich (Kf) and Langmuir (Qo) adsorption parameters. These values followed the same trend of the batch experiments. The maximum sorption capacity of sodalite increased in the order Pb2+ > Cd2+ > Zn2+ at the same condition. The effect of different parameters, such as contact time, and temperature were also investigated. The present investigation also revealed that iodate sodalite as sorbents can serve as low-cost adsorbent with higher sorption capacities towards heavy metals.