Investigating Galvanic Corrosion in Low-Alkalinity Water: The Effects of pH, High Dose Corrosion Inhibitors, and Dissolved Inorganic Carbon

Abstract

The objective of this study was to evaluate galvanic corrosion potential under various pH conditions, buffering capacities, and corrosion inhibitors including zinc orthophosphate (ZOP) and orthophosphate (OP). Bench-scale dump-and-fill experiments evaluated metals release from a lead and copper couple under stagnant conditions. Key findings from this study were that increasing DIC from 3 to 7 or 17 mg CaCO3/L significantly reduced lead release with or without corrosion inhibitor; however, the lowest lead concentrations were observed in water conditions with corrosion inhibitor addition. However, addition of 20 mg PO4/L as OP exacerbated lead release in some cases; though dissolved lead release was always below 28 µg/L, particulate lead was as much as 4 times greater compared to no corrosion inhibitor. Overall, this study demonstrated the potential of high dose ZOP and OP for lead corrosion control in drinking water, however, overdosing OP can lead to exacerbated particulate concentrations.