Volume 4, Issue 4 e1294
ORIGINAL RESEARCH

Sequential electrolysis and reverse osmosis to improve arsenic removal from water

Yizhi Hou

Yizhi Hou

Department of Civil, Construction and Environmental Engineering, Marquette University, Milwaukee, Wisconsin, USA

A.O. Smith Corporation Technology Center, Milwaukee, Wisconsin, USA

Contribution: Conceptualization, Resources, Data curation, Formal analysis, Funding acquisition, ​Investigation, Visualization, Methodology, Writing - original draft, Writing - review & editing

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Brooke K. Mayer

Corresponding Author

Brooke K. Mayer

Department of Civil, Construction and Environmental Engineering, Marquette University, Milwaukee, Wisconsin, USA

Correspondence

Brooke K. Mayer, Department of Civil, Construction and Environmental Engineering, Marquette University, Milwaukee, WI 53233, USA.

Email: [email protected]

Contribution: Supervision, Project administration, Writing - review & editing

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First published: 22 July 2022
Associate Editor: Chad Seidel

Funding information: A.O. Smith Corporation

Abstract

Reverse osmosis (RO) typically removes >98% arsenate (As[V]) but removes arsenite (As[III]) comparatively poorly (approximately 50%–80%). Therefore, oxidizing As(III) to As(V) can improve arsenic removal using RO. In this study, electrolytic oxidation was used to oxidize As(III) in the feed water, and an extreme low-pressure RO membrane was subsequently used to remove the arsenic. Using Ti/IrO2 electrodes under 30 mA DC current in 500 mg/L NaCl solution primarily generated free chlorine, which completely oxidized 300 μg/L As(III) to As(V). Subsequent arsenic removal by RO increased from 54.2% without oxidation to 98.2% with oxidation. Using electrolysis-RO, arsenic removal significantly increased beyond RO alone, even in the presence of ferrous iron and natural organic matter. When sulfide and As(III) are present in water, they react to produce thioarsenate ions, the formation of which increased As(III) removal to 90% without electrolytic oxidation and electrolytic oxidation did not improve arsenic removal beyond these levels.

CONFLICT OF INTEREST

The authors declare no conflicts of interest that would otherwise impact or otherwise influence the production of this work.

DATA AVAILABILITY STATEMENT

The data that support the findings of this study are available from the corresponding author upon reasonable request.