Abstract
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.
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•Coal fly ash was used to synthesize nano-zeolites hydrothermally.•The modification of the zeolites to a positive surface charge was successful.•The BET analysis showed a surface area of 85.53 m2/g for the modified zeolites.•10 g/L adsorbent dosage was optimal for sulfate removal.•The zeolites had the maximum sulfate adsorption capacity of 42.25 mg/g.