Selective removal of chromium from different aqueous systems using magnetic MCM-41 nanosorbents

• Magnetic nanosorbents of excellent chromium adsorption selectivity (Kd>25,000mLg−1). • Separates better than 90% chromium in aqueous systems with capacity of ca. 1.3±0.2mmolg−1. • High magnetization (8.30emug−1), excellent dispersibility and recoverability from water. • Stable in tap and natura...

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Bibliographic Details
Published in:Chemical engineering journal (Lausanne, Switzerland : 1996) Switzerland : 1996), 2011-08, Vol.172 (2-3), p.728-734
Main Authors: Chen, Xinqing, Lam, Koon Fung, Yeung, King Lun
Format: Article
Language:English
Subjects:
Adsorption
Applied sciences
Chemical engineering
Continental surface waters
Exact sciences and technology
Heavy metals
Magnetic nanoparticles
Mesoporous silica
Natural water pollution
Pollution
Separation
Water treatment
Water treatment and pollution
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Summary:• Magnetic nanosorbents of excellent chromium adsorption selectivity (Kd>25,000mLg−1). • Separates better than 90% chromium in aqueous systems with capacity of ca. 1.3±0.2mmolg−1. • High magnetization (8.30emug−1), excellent dispersibility and recoverability from water. • Stable in tap and natural waters even in presence of minerals and humic compounds. Chromium (VI) oxyanions were removed selectively from various aqueous systems using magnetic MCM-41 nanosorbents of large surface area (>550m2g−1) and high magnetization (≥8.0emug−1). 10nm magnetic iron oxide nanoparticles were embedded within 250±50nm MCM-41 to obtain a highly dispersible magnetic material, magMCM-41 that can be easily removed by a magnetic field. A highly selective nanosorbent was obtained by grafting aminopropyls and adsorbing Fe3+ on the pores of the magMCM-41. Chromium oxyanions were selectively removed over the pH range of 2–7 with high adsorption capacity of ca. 1.9mmolg−1 (ca. 100mgg−1) and Kd>25,000mLg−1 for single and binary component adsorptions from distilled, tap, mountain stream and river waters. The presence of calcium in the tap and natural waters as well as humic compounds in mountain stream and river waters resulted in a slightly lower chromium adsorption, but did not affect its superb selectivity (ca. 97%). The adsorption and separation of the chromium oxyanions were adequately described by Freundlich and LeVan–Vermeulen equations.
ISSN:1385-8947
1873-3212
DOI:10.1016/j.cej.2011.06.042