Effects of NOM properties on copper release from model solid phases

Area of Science:

• Environmental Chemistry
• Geochemistry
• Water Chemistry

Background:

• Copper release from solid phases is influenced by natural organic matter (NOM).
• Understanding NOM's role is crucial for predicting metal behavior in aquatic systems.
• Model solid phases like tenorite (CuO) and malachite (Cu2(OH)2CO3) are used to study these interactions.

Purpose of the Study:

• To investigate how the properties and concentrations of NOM affect copper release from tenorite and malachite.
• To determine the impact of NOM alteration (chlorination, ozonation) on copper release dynamics.
• To correlate NOM characteristics with copper release and surface potential changes.

Main Methods:

• Utilized model copper solid phases: tenorite (CuO) and malachite (Cu2(OH)2CO3).
• Applied differential absorbance spectroscopy (DAS) and high-performance size-exclusion chromatography (HPSEC) to characterize NOM.
• Measured copper release and ζ-potential of the model solids under varying NOM conditions.

Main Results:

• Unaltered humic and fulvic acids significantly increased copper release.
• NOM alteration by chlorination and ozonation suppressed or eliminated copper release enhancement.
• Higher apparent molecular weight, aromaticity, and specific functional groups in NOM correlated with increased copper release.
• ζ-potential changes of the model solids were strong predictors of copper release, particularly for malachite.

Conclusions:

• NOM properties, especially molecular weight and functional groups, critically control copper release from model solids.
• Oxidative treatment of NOM diminishes its ability to enhance copper release by altering its surface activity and charge.
• Spectroscopic parameters like SUVA254 and ζ-potential are key indicators of NOM-driven metal release.