Removal of uranium (VI) from aqueous solution by acid modified zeolites

Abstract

The objective of this study was the review of natural zeolite, modified with acid, as a candidate material for the remediation of groundwater contaminated by uranium(VI). The modified zeolite samples were obtained by treatment of natural zeolite - clinoptilolite with acids: hydrochloric, oxalyc and citric. Starting and modified zeolites were characterized by chemical analysis, SEM, XRPD analysis, IR spectroscopy, thermal (TG/DT) analysis and by determination of cation exchange capacity, while starting and nonadsorbed amounts of uranium(VI) ion were determined by fluorometric method. Batch experiments were conducted to investigate the effect of solid/liquid ratio, pH and time on the U(VI) uptake by zeolite. Modification of zeolitic tuff with acids significantly increased adsorption of uranium(VI). The highest adsorption of uranium(VI) ion was achieved on clinoptilolite modified with hydrochloric acid. Uranium(VI) adsorption data for zeolite modified with hydrochloric acid was fitted to the Langmuir model.