Iron Oxides Reactivity: A Unified Surface Complexation Modeling Approach

N. Bompati, M. Hawkins, Michael L. Machesky

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

Goldschmidt2017 AbstractIron oxides reactivity: A unified surface complexation modeling approachN.BOMPOTI1*,M.CHRYSOCHOOU1,M.MACHESKY21Department of Civil and Environmental Engineering, University of Connecticut, Storrs, CT, USA(*correspondence: nefeli.bompoti@uconn.edu)2Illinois State Water Survey, Prairie Research Institute, Champaign, IL, USAIron oxides and oxyhydroxides are among the most reactive surfaces in the environment and various models have been developed to describe the reactivity of various phases such as goethite and ferrihydrite.Although surface complexation models (SCMs) provide a robust description of adsorption under variousconditions,their application to mineral assemblages is still difficult,due tothehigh degree ofcomplexity and parametrization.In this study, we propose a unifiedSCMto describe chromate adsorption on three iron oxides: ferrihydrite, hematite and goethite.The unified approach focuses on employing a single set of electrolyte and specific adsorption equilibrium constants, while modeling surface charge using individual mineral structure and surface properties. Specifically, a 3–site model was used to describe surface protonation using site densities derived from the structureand morphology,and protonation constants derived from the literature or fitted to mineral-specific charging curves. This approach has been able to capture the differences onpoints of zero net proton charge (PZNPCs)onvariousFH chargingcurves[1].For chromate adsorption, insights from spectroscopy and batch adsorption experiments areincorporated to build a model that is able to simulate adsorption using a single set of electrolyte constants and a narrow range of surface complexation constants. Some results on simulating chromate adsorption on the threeiron oxides areshown in Figure 1. F
Original languageEnglish (US)
Title of host publicationGoldschmidt 2017 Abstracts
StatePublished - 2017

Keywords

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    Bompati, N., Hawkins, M., & Machesky, M. L. (2017). Iron Oxides Reactivity: A Unified Surface Complexation Modeling Approach. In Goldschmidt 2017 Abstracts