In Situ 2D Maps Of Ph Shifts Across Brass-Lead Galvanic Joints Using Microelectrodes

Keywords

2D map; corrosion; galvanic joints; in situ measurement; microelectrodes

Abstract

Galvanic corrosion in drinking water distribution systems, such as conditions following partial lead service line replacement, can be a significant source of lead in tap water. The objective of this work was to measure the pH directly near metal surfaces using a novel experimental tool in order to understand the water chemistry at a lead-containing galvanic couple in drinking water. Specifically, pH microprofiles in the proximity of corroding metal surfaces were measured using a microelectrode to construct detailed in situ 2D spatial maps of the pH across a galvanic couple at 100 μm above the metal's surface under flowing and stagnation conditions. The opposite pH trend was directly observed across the galvanic couple under flow and stagnation conditions. Water stagnation resulted in a pH at the anode (leaded solder) of 1.5 pH units lower than the bulk water pH (9.0) and as much as 2.5 pH units lower than the cathode (brass). These conditions can enhance lead release at the anode, which reflects different anodic-cathodic relationships of coupled metals primarily controlled by water flow. Most importantly, this work has demonstrated the ability to make real pH measurement at the surface of corroding metals using a novel microelectrode approach.

Publication Date

2-1-2017

Publication Title

Measurement Science and Technology

Volume

28

Issue

2

Document Type

Article

Personal Identifier

scopus

DOI Link

https://doi.org/10.1088/1361-6501/28/2/025101

Socpus ID

85010931363 (Scopus)

Source API URL

https://api.elsevier.com/content/abstract/scopus_id/85010931363

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