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In situ monitoring of Pb2+ leaching from the galvanic joint surface in a prepared chlorinated drinking water
Citation:
Ma, X., S. Armas, M. Soliman, D. Lytle, K. Dhumbimuni-Torres, L. Tetard, AND W. Lee. In situ monitoring of Pb2+ leaching from the galvanic joint surface in a prepared chlorinated drinking water. ENVIRONMENTAL SCIENCE & TECHNOLOGY. American Chemical Society, Washington, DC, 52:2126-2133, (2018). https://doi.org/10.1021/acs.est.7b05526
Impact/Purpose:
A novel method using a micro-ion-selective electrode (micro-ISE) technique was developed for in situ lead monitoring at water-metal interface of a brass-leaded solder galvanic joint in a prepared chlorinated drinking water environment. The developed lead micro-ISE (100 µm tip diameter) showed excellent performance toward soluble lead (Pb2+) with the sensitivity of 22.2±0.5 mV decade-1 and limit of detection (LOD) of 1.22×10-6 M (0.25 mg L-1). The response time was less than 10 seconds with a working pH range of 2.0–7.0. Using the lead micro-ISE, lead concentration microprofiles were measured from the bulk to the metal surface over time. Combined with two-dimensional (2D) pH mapping, this work clearly demonstrated that Pb2+ ions build-up across the lead anode surface was substantial, non-uniform, and dependent on local surface pH. A large pH gradient (ΔpH: 6.0) developed across the brass and leaded-tin solder joint coupon. Local pH decreases were observed above the leaded solder to a pH as low as 4.0indicating it was anodic relative to the brass. The low pH above the leaded solder supported elevated lead levels where even small local pH differences of 0.6 (ΔpH: 0.6) resulted in 44 times different surface lead concentrations (42.9 vs. 11.6 mg L-1) and 5 times different fluxes (18.5×10-6 vs. 3.5×10-6 mg cm-2 s-1). Continuous surface lead leaching monitoring and characterization found that free chlorine was one of the primary corrosion drivers resulting in lead build-up..
Description:
A novel method using a micro-ion-selective electrode (micro-ISE) technique was developed for in situ lead monitoring at water-metal interface of a brass-leaded solder galvanic joint in a prepared chlorinated drinking water environment. The developed lead micro-ISE (100 µm tip diameter) showed excellent performance toward soluble lead (Pb2+) with the sensitivity of 22.2±0.5 mV decade-1 and limit of detection (LOD) of 1.22×10-6 M (0.25 mg L-1). The response time was less than 10 seconds with a working pH range of 2.0–7.0. Using the lead micro-ISE, lead concentration microprofiles were measured from the bulk to the metal surface over time. Combined with two-dimensional (2D) pH mapping, this work clearly demonstrated that Pb2+ ions build-up across the lead anode surface was substantial, non-uniform, and dependent on local surface pH. A large pH gradient (ΔpH: 6.0) developed across the brass and leaded-tin solder joint coupon. Local pH decreases were observed above the leaded solder to a pH as low as 4.0indicating it was anodic relative to the brass. The low pH above the leaded solder supported elevated lead levels where even small local pH differences of 0.6 (ΔpH: 0.6) resulted in 44 times different surface lead concentrations (42.9 vs. 11.6 mg L-1) and 5 times different fluxes (18.5×10-6 vs. 3.5×10-6 mg cm-2 s-1). Continuous surface lead leaching monitoring and characterization found that free chlorine was one of the primary corrosion drivers resulting in lead build-up..
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DOI: In situ monitoring of Pb2+ leaching from the galvanic joint surface in a prepared chlorinated drinking water
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In situ monitoring of Pb2+ leaching from the galvanic joint surface in a prepared chlorinated drinking water