Eco-Friendly Synthesis of Aluminosilicate Bromo Sodalite from Waste Coal Fly Ash for the Removal of Copper and Methylene Blue Dye

The synthesis of sodalite from fly ash seems to be one of the most promising alternatives as it has emphasis on value addition to the waste material. In view of this problem, this study investigated a working procedure for determining the degree of reaction of fly ash subjected to alkali activation at mild temperature, during the synthesis of bromo sodalite, . Obtained sodalite product was analyzed for their composition and physicochemical properties by X-ray diffraction, Fourier transform infrared spectroscopic analysis, inductively coupled plasma, Brunauer-Emmett-Teller surface area analysis, thermogravimetric analysis and scanning electron microscope. The crystal structures show cubic symmetry in a space group . The unit cell parameter , and the corresponding Al-O-Si angle is found to be . The adsorption behavior of synthesized bromo sodalite has been studied in order to determine its applicability for the adsorption of the copper ion and methylene blue dye from their aqueous solutions. Factors influencing the adsorption process including contact time, sodalite concentration variation, copper ion and dye concentration variation were studied for adsorption of copper and methylene blue dye. Copper is removed due to two processes, viz adsorption and ion exchange, whereas methylene blue is removed due to only adsorption. The maximum adsorption capacity of synthesized sodalite was found to be 52.63 mg/g for copper ion removal and 45.46 mg/g for methylene blue dye removal. Thermodynamic parameters like Gibbs free energy (, entropy change () and enthalpy change () were calculated. Present adsorbent showed much better adsorption capacity for both copper ion and methylene blue as compare to reported low-cost adsorbents.