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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 P43n, 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. [ABSTRACT FROM AUTHOR]

Aluminosilicate azide cancrinite, Na8[AlSiO4]6(N3)2.4(H2O)4.6, has been prepared for the first time from zeolite-A, followed by hydrothermal processing at low temperature. After crystallization, the sample was characterized by appropriate physicochemical techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), infrared spectroscopy (IR), thermal gravimetric analysis (TGA), and Brunauer-Emmett-Teller (BET) surface area. In the present study, attention was focused on investigating the removal performance of heavy metal ions (Cd2+, Pb2+, and Ni2+) in aqueous solution on pure aluminosilicate azide cancrinite. The kinetics of the process and sorption capacity of the adsorbent was determined in relation to the effect of various factors affecting on the adsorption process. The parameters in this study included contact time, metal ion concentration, temperature, and adsorbent dosage. The removal mechanism of metal ions followed adsorption and ion exchange process. Adsorption data has been interpreted in terms of Langmuir and Freundlich equations. The selectivity of the studied metal ions was determined as Pb2+ > Cd2+ > Ni2+. Thermodynamic parameters, i.e., equilibrium constant (Kc), free energy (ΔG°), entropy (ΔS°), and enthalpy (ΔH°) for adsorption, were computed from the experimental data. [ABSTRACT FROM AUTHOR]