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Georgeite: A Rare Copper Mineral with Important Drinking Water Implications
Citation:
Lytle, D., D. Wahman, M. Schock, M. Nadagouda, S. Harmon, K. Webster, AND J. Botkins. Georgeite: A Rare Copper Mineral with Important Drinking Water Implications. Chemical Engineering Journal. Elsevier BV, AMSTERDAM, Netherlands, 355:1-10, (2019). https://doi.org/10.1016/j.cej.2018.08.106
Impact/Purpose:
Since the implementation of the Lead and Copper Rule, a large amount of research has been conducted on copper corrosion and solubility, including the establishment of the “cupric hydroxide model”. This conceptual model describes the temporal aging and associated solubility changes of copper minerals. Although the model explains copper levels in field observations reasonably well, there are aspects of the model that are not well understood, including a lack of evidence to support the presence of cupric hydroxide in drinking water distribution systems. The objective of this study was to examine the effect of water chemistry on the solubility and properties of newly precipitated cupric, Cu(II), solids, including conclusive mineral identification. Bench-scale copper precipitation tests generated copper solids under a matrix of targeted pH (7, 8, and 9) and dissolved inorganic carbon (10, 50 and 100 mg C/L) conditions. Copper solids were analyzed using a combination of material analysis tools including: inorganic carbon analysis, X-ray diffraction (XRD), Fourier transform-infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA), and polarizing light microscopy. Resulting copper solids were X-ray amorphous and isotropic under all conditions and ranged from light blue to blue in color. Based on repeated analysis, georgeite (Cu2(CO3)(OH)2·6H2O) was identified for the first time in water as the solid at all test conditions. Georgeite is an extremely rare, amorphous malachite analog, and because of its rarity, very little has been reported on its presence in any environment. The results can be used to improve the prediction of copper release and control for new copper plumbing and guide treatment strategies for drinking water systems.
Description:
Since the implementation of the Lead and Copper Rule, a large amount of research has been conducted on copper corrosion and solubility, including the establishment of the “cupric hydroxide model”. This conceptual model describes the temporal aging and associated solubility changes of copper minerals. Although the model explains copper levels in field observations reasonably well, there are aspects of the model that are not well understood, including a lack of evidence to support the presence of cupric hydroxide in drinking water distribution systems. The objective of this study was to examine the effect of water chemistry on the solubility and properties of newly precipitated cupric, Cu(II), solids, including conclusive mineral identification. Bench-scale copper precipitation tests generated copper solids under a matrix of targeted pH (7, 8, and 9) and dissolved inorganic carbon (10, 50 and 100 mg C/L) conditions. Copper solids were analyzed using a combination of material analysis tools including: inorganic carbon analysis, X-ray diffraction (XRD), Fourier transform-infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA), and polarizing light microscopy. Resulting copper solids were X-ray amorphous and isotropic under all conditions and ranged from light blue to blue in color. Based on repeated analysis, georgeite (Cu2(CO3)(OH)2·6H2O) was identified for the first time in water as the solid at all test conditions. Georgeite is an extremely rare, amorphous malachite analog, and because of its rarity, very little has been reported on its presence in any environment. The results can be used to improve the prediction of copper release and control for new copper plumbing and guide treatment strategies for drinking water systems.
URLs/Downloads:
DOI: Georgeite: A Rare Copper Mineral with Important Drinking Water Implications
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