Zeolite supported mono- and bimetallic oxides: Promising adsorbents for removal of As(V) in aqueous solutions

► Monometallic (Fe or Al) and bimetallic (FeAl) oxides were supported on zeolite. ► The presence of Al or Fe in zeolite enhanced As(V) removal capacity significantly. ► The bimetallic oxide associated zeolite had the highest adsorption capacity. ► The sorption patterns fit well to the Freundlich and...

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Bibliographic Details
Published in:Chemical engineering journal (Lausanne, Switzerland : 1996) Switzerland : 1996), 2013-03, Vol.220, p.402-411
Main Authors: Simsek, Esra Bilgin, Özdemir, Ercan, Beker, Ulker
Format: Article
Language:English
Subjects:
Adsorbents
Adsorption
Aluminum
anions
Applied sciences
aqueous solutions
Arsenic
Batch adsorption
Chemical engineering
Exact sciences and technology
Ferrous alloys
Gibbs free energy
Intermetallic compounds
Intermetallics
iron
Mono- and bimetallic oxides
Natural zeolite
Oxides
sorption isotherms
Surface chemistry
temperature
Zeolites
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Summary:► Monometallic (Fe or Al) and bimetallic (FeAl) oxides were supported on zeolite. ► The presence of Al or Fe in zeolite enhanced As(V) removal capacity significantly. ► The bimetallic oxide associated zeolite had the highest adsorption capacity. ► The sorption patterns fit well to the Freundlich and D–R models. In this study, synthesis and characterization of novel adsorbents based on natural zeolite (clinoptilolite) supported mono- (Fe or Al) and bimetallic (FeAl) oxides for adsorption of arsenate from aqueous solution were investigated. Batch sorption experiments were carried out at different pH (3.0, 5.0 and 7.0), temperature (298, 318 and 338K) and initial metal concentration (0.5, 5.0 and 9.5mgL−1) values. The experimental results showed that aluminum (ZNaAl) and iron (ZNaFe(II)) modified zeolites enhanced the arsenate uptake significantly. Furthermore, bimetallic oxide associated zeolite, ZNaAlFe(III), showed highest adsorption capacity as compared to ZNaAl and ZNaFe(II), indicating that aluminum impregnation can provide more adsorption sites (AlOH) to As(V) anions. Maximum sorption capacities were achieved at pH 5 for ZNa (0.026mgg−1), ZNaAl (1.50mgg−1) and ZNaAlFe(III) (3.86mgg−1) and at pH 3 for ZNaFe(II) (3.02mgg−1). The results suggest that As(V) adsorption process is dominantly followed by surface complexation reactions for ZNaAl and ZNaAlFe(III) adsorbents while columbic interactions occur on the surface of ZNaFe(II). Dubinin–Radushkevich and Freundlich isotherm models fitted the equilibrium data better than Langmuir isotherm. The Gibbs free energy values were found as negative for all sorbents, which indicates the adsorption of arsenate on modified zeolites is feasible and spontaneous.
ISSN:1385-8947
1873-3212
DOI:10.1016/j.cej.2013.01.070