Presentation Title

Impacts of Chlorine and Chloramine on the Transport and Transformation of As in the Presence of Ferrihydrite

Start Date

November 2016

End Date

November 2016

Location

HUB 302-#98

Type of Presentation

Poster

Abstract

Arsenic(As) is a ubiquitous contaminant in groundwater, and the redox transformation of As significantly influences its fate and transport. The water distribution pipes are majorly made of iron-based materials, which is easily oxidized to iron oxides, such as ferrihydrite. The addition of disinfectants like chlorine (HOCl) and chloramine (NH2Cl) may have impacts on the redox transformation of As, further influences its fate and transport in the environment. This study investigated the impacts of chlorine and chloramine on the transformation and transport of As in the presence of ferrihydrite in water distribution systems. Batch experiments were conducted with varying level of As (400-2000 μg/L), ferrihydrite (1 g/L) and disinfectants (2000 μg/L) (e.g. chlorine or chloramine). The impacts of pH and the dosage of the disinfectants were examined. The preliminary results showed that chlorine was more reactive with ferrihydrite than chloramine. In the presence of As and ferrihydrite, both chlorine and chloramine were quickly consumed. The reaction between As(III) and chlorine was enhanced at pH 9. The higher ratio of disinfectants to As also increased the oxidation of adsorbed As(III). The study examined fundamental understanding of ascetic chemistry, and provided guidance for the utilities to prevent leaching of As from iron-containing pipes when adding disinfectants.

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Nov 12th, 4:00 PM Nov 12th, 5:00 PM

Impacts of Chlorine and Chloramine on the Transport and Transformation of As in the Presence of Ferrihydrite

HUB 302-#98

Arsenic(As) is a ubiquitous contaminant in groundwater, and the redox transformation of As significantly influences its fate and transport. The water distribution pipes are majorly made of iron-based materials, which is easily oxidized to iron oxides, such as ferrihydrite. The addition of disinfectants like chlorine (HOCl) and chloramine (NH2Cl) may have impacts on the redox transformation of As, further influences its fate and transport in the environment. This study investigated the impacts of chlorine and chloramine on the transformation and transport of As in the presence of ferrihydrite in water distribution systems. Batch experiments were conducted with varying level of As (400-2000 μg/L), ferrihydrite (1 g/L) and disinfectants (2000 μg/L) (e.g. chlorine or chloramine). The impacts of pH and the dosage of the disinfectants were examined. The preliminary results showed that chlorine was more reactive with ferrihydrite than chloramine. In the presence of As and ferrihydrite, both chlorine and chloramine were quickly consumed. The reaction between As(III) and chlorine was enhanced at pH 9. The higher ratio of disinfectants to As also increased the oxidation of adsorbed As(III). The study examined fundamental understanding of ascetic chemistry, and provided guidance for the utilities to prevent leaching of As from iron-containing pipes when adding disinfectants.