Affiliation:
1. Oak Ridge Institute for Science and Education (ORISE) Post‐Doctoral Fellow at U.S. Environmental Protection Agency Cincinnati Ohio USA
2. College of Engineering and Applied Science University of Cincinnati Cincinnati Ohio USA
3. Center for Environmental Solutions & Emergency Response U.S. Environmental Protection Agency Cincinnati Ohio USA
4. Department of Civil, Environmental, and Construction Engineering University of Central Florida Orlando Florida USA
Abstract
AbstractDuctile iron and copper coupons were aged 137–189 days and 2 days, respectively, with 2 mg Cl2 L−1 monochloramine under four water chemistries (pH 7 or 9 and 0 or 3 mg L−1 orthophosphate). Subsequently, microelectrode profiles of monochloramine concentration, oxygen concentration, and pH were measured from the bulk water to near the coupon reactive surface, allowing estimation of flux and apparent surface reaction rate constants for monochloramine and oxygen. Both metals showed similar trends with orthophosphate where orthophosphate decreased metal reactivity with monochloramine (pH 9) and oxygen (pH 7). Comparing iron and copper coupons, apparent surface reaction rate constants for monochloramine and oxygen were one and two orders of magnitude greater, respectively, for iron coupons under all conditions. Overall, this research provides the first insights into monochloramine concentration, oxygen concentration, and pH by direct measurement near ductile iron and copper reactive surfaces aged in the presence of monochloramine.