Adsorption of Fluorine in Wastewater by Alkali-Thermal Modified Fly Ash
hydrothermal modified fly ash was prepared under alkaline conditions and employed to remove fluorine in wastewater.Both the ash and the modified fly ash were characterized by XRD and SEM,and fluoride adsorption performance of the fly ash before and after modification were compared in simulated wastewater.The effects of the fly ash dosage,initial pH,and temperature on fluoride adsorption were also investigated.The results showed that the adsorption sites and pores on the fly ash surfaces increased after alkali-thermal modification.The adsorption potential was significantly improved.The removal rate of fluoride ion was as high as 94.7％under 2 g/L of modified fly ash dosage,initial pH 7.6,and 20℃conditions.The reaction reached adsorption equilibrium at 60 min,and the adsorption process was endothermic.There was no risk of secondary pollution in fluorine removal from wastewater by the alkali-thermal modified fly ash.The results provided theoretical basis and technical reference for the high-value utilization of fly ash and fluorine removal from wastewater.
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