Modification of a natural zeolite with Fe(III) for simultaneous phosphate and ammonium removal from aqueous solutions

BACKGROUND The incorporation of Fe( III ) was performed in a natural clinoptilolite (Z‐N) for simultaneous phosphate and ammonium removal. RESULTS The existence of hydroxyl groups (≅Fe‐ OH ) in the iron zeolite (Z‐Fe) enhances the phosphate uptake from 0.6 ± 0.1 mg‐P g −1 in Z‐N to 3.4 ± 0.2 mg‐P g −1 in Z‐Fe. However, the ammonium sorption capacity slightly decreases from 33 ± 2 mg‐N g −1 in Z‐N to 27 ± 2 mg‐N g −1 in Z‐Fe. The equilibrium and kinetics sorption were well explained by the Langmuir isotherm and the intraparticle diffusion model, respectively. CONCLUSIONS Both the phosphate and ammonium uptake were slightly affected by the coexistence of competing ions. The phosphate sorption capacity of iron zeolite was decreased in the regeneration cycles. Desorption using a 1 mol L −1 NaOH solution under dynamic conditions provided higher enrichment factors for ammonium than phosphate.