Impact of pH, Dissolved Inorganic Carbon, and Polyphosphates for the Initial Stages of Water Corrosion of Copper Surfaces Investigated by AFM and NEXAFS

Abstract

Nanoscale studies at the early stages of the exposure of copper surfaces after systematic treatments in synthesized water solutions can provide useful information about corrosion processes. The corrosion and passivation of copper surfaces as influenced by pH, dissolved inorganic carbon (DIC) and polyphosphate levels were investigated with nanoscale resolution, to gain insight about changes in surface morphology and the composition of adsorbates. Information regarding the surface morphology after chemical treatment was provided by atomic force microscopy (AFM) and the corresponding chemical composition of treated surfaces was obtained with near-edge X-ray absorption fine structure (NEXAFS). Changes in the surface topography of copper samples were readily detected within only 6 to 24 hours of exposure to water solutions. Topographic views of surface changes are presented to compare the growth of adsorbate layers that take place during the evolution of mineral deposits. Slight changes in the pH and concentrations of phosphates in the water samples have a substantial impact on the rate of growth and composition of surface deposits. These studies provide insight on the mechanisms and resulting chemical constituents that lead to surface passivation or corrosion of copper, simulating conditions that occur in water distribution systems.

Quartz Crystal Microbalance with Dissipation: A New Approach of Examining Corrosion of New Copper Surfaces in Drinking Water

“…The QCMD analyses showed that both increasing water pH from 6.5 to 9.0 and the addition of 6 mg/L PO 4 at a water pH of 6.5 and 9.0 effectively inhibited Cu mass changes. The mass changes corresponded to physiochemical changes on Cu surfaces based on QCMD measurements, which was also in agreement with observations of early Cu corrosion in water by others. − Previous studies, for example, showed that increasing water pH reduced Cu release by reducing the solubility of Cu corrosion byproducts deposited on the surface via influencing the diffusion process from the passivating film layer. ,, …”

“…Therefore, early corrosion and associated mineralogical changes of Cu surfaces are extremely important in Cu surface passivation and degradation because of its potential impact on the Cu levels in tap water that are regulated via the Lead and Copper Rule (LCR) via the Safe Drinking Water Act. , The LCR requires no more than 1.3 mg/L of total Cu in selected home tap water, and adjusting water parameters such as water pH, dissolved inorganic carbon (DIC), and phosphate inhibitors are recommended for Cu surface passivation and reducing total Cu levels in tap water. Previous studies focused on examining the ex situ long-term (up to years) impact of water quality changes and disruptive events on Cu corrosion cuprosolvency and scale passivation. − Only a few studies have examined the impact of water pH, phosphate inhibitors, and DIC on the surface roughness, structures, and morphology of the formed nanoscale corrosion byproducts during the early Cu corrosion (<24 h). − As Cu continues to be commonly used to construct drinking water plumbing in new homes and buildings, a better understanding of early in situ interfacial interactions between the drinking water and new Cu surfaces is needed. It can provide insight into the kinetics of early Cu corrosion and immediate Cu surface changes in response to water quality changes.…”

Surface Electronic Structure and Mechanical Characteristics of Copper–Cobalt Oxide Thin Film Coatings: Soft X-ray Synchrotron Radiation Spectroscopic Analyses and Modeling

“…These main peaks arise from the dipole transitions of the Cu 2p 1/2 for L 2 and Cu 2p 3/2 for L 3 into the empty d states. 40 The Cu-L 3 peak is more sensitive to the local environment than the Cu-L 2 peak, which can be attributed to the Cu 2+ ions. 41−45 This observation reinforces the conclusion arrived at in the previous XPS analysis that there would be changes in the local coordination if the copper/cobalt concentration ratio is higher than 1, due to the loss of octahedral Cu + .…”

Nanoscale surface characterization of aqueous copper corrosion: Effects of immersion interval and orthophosphate concentration

“…Scanning probe-based characterizations have been use to view the surface morphology of corrosion products formed on aluminum alloys [28], stainless steel A c c e p t e d M a n u s c r i p t 4 [29], copper [30,31] and iron [32]. Recently, AFM has been applied for surface analysis of the degradation of metals used in water distribution systems [13,33,34].…”