Synthesis, modification and characterization of nano-zeolites from coal fly ash for the removal of sulfates in wastewater

This study used coal fly ash (CFA) to synthesize nano-zeolite for sulfate removal from aqueous solutions at neutral pH. The zeolitic material was synthesized by hydrothermic treatment of CFA with a 2 M NaOH solution and the synthezised zeolites were modified to enhance the surface charge and characterized pre and post-sulfate adsorption using XRF, XRD, FTIR, SEM-EDS and BET to identify the crystalline and microstructural alterations. The BET analysis showed a surface area of 85.53 m²/g and 1.059 m²/g for the modified zeolites and the CFA respectively. Sulfate adsorption investigations demonstrated that 10 g/L was the optimum adsorbent dosage and zeolites had the maximum adsorption capacity of 42.25 mg/g and fitted well into second order kinetic model. Correlated with the morphology, surface charge, mineralogy, composition and kinetic studies, the results demonstrated that the synthesized zeolites are suitable to uptake sulfate ions from the wastewater. The results of this study showed that nano-zeolites can be synthesized from CFA and can be used in the removal of sulfates from synthetic wastewater at room temperatures.