Recently, it has been demonstrated that organic contaminants can be oxidized during the reaction of Fe(II)-containing clay minerals with oxygen, similar to what is known for dissolved Fe(II). Because Fe(II) in clay minerals is stably bound in a solid matrix, the use of these abundant and low-cost natural materials could provide a sustainable approach for implementing Fe-based advanced oxidation processes in water treatment, both in developed and developing countries.  However, it is unknown how the difference in binding environment between aqueous Fe(II) and clay mineral Fe(II) alters the mechanism of reactive oxidizing species (ROS) production and how clay mineral properties determine the efficiency of the advanced oxidation process.  To address this knowledge gap, we carried out a kinetic study using a range of model organic contaminants to probe the oxidative reactivity in our clay mineral systems. We related contaminant oxidation with simultaneously measured Fe(II) consumption, which was used as a proxy for reactive oxidizing species formation, and determined the efficiency of the overall advanced oxidation process. To determine the effect of clay mineral properties on the oxidation efficiency, we used standard clay minerals differing in total clay mineral Fe content and the location of Fe binding. Additionally, we used selective scavengers and likely intermediate species formed during the Fe(II) oxygenation reaction to verify our hypothesized reaction mechanism. Finally, we integrated all results to developed a mathematical model for the oxidation reaction.

Using clay minerals in an advanced oxidation process for water treatment: insights from kinetic studies

256th National Meeting (2018)

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