Removal of arsenic from water using manganese (III) oxide: Adsorption of As(III) and As(V)

ABSTRACT

Removal of arsenic from water was evaluated with manganese (III) oxide (Mn₂O₃) as adsorbent. Adsorption of As(III) and As(V) onto Mn₂O₃ was favorable according to the Langmuir and Freundlich adsorption equilibrium equations, while chemisorption of arsenic occurred according to the Dubinin–Radushkevich equation. Adsorption parameters from the Langmuir, Freundlich, and Temkin equations showed a greater adsorption and removal of As(III) than As(V) by Mn₂O₃. Maximum removal of As(III) and As(V) occurred at pH 3–9 and at pH 2, respectively, while removal of As(V) in the pH range of 6–9 was 93% (pH 6) to 61% (pH 9) of the maximum removal. Zeta potential measurements for Mn₂O₃ in As(III) was likely converted to As(V) solutions indicated that As(III) was likely converted to As(V) on the Mn₂O₃ surface at pH 3–9. Overall, the effective Mn₂O₃ sorbent rapidly removed As(III) and As(V) from water in the pH range of 6-9 for natural waters.

KEYWORDS:

• Adsorption
• arsenic
• As(III)
• As(V)
• manganese oxides
• pH

Acknowledgment

The authors would like to thank Snover Punia from the Department of Civil and Materials Engineering at the University of Illinois at Chicago for assistance with the chemical analysis.