The Reactivity and Redox-Induced Nucleation and Growth of Goethite on Synthetic Aluminum Substituted Hematite Nanoparticles

Academic Research Topics in Environmental Measurement and Monitoring
Poster Presentation

Prepared by A. Hildebrandt1, A. Soroush2, W. Arnold2, C. Jonhston1, R. Penn1
1 - University of Minnesota, University of Minnesota, Department of Chemistry, 139 Smith Hall, 207 Pleasant St SE, Minneapolis, Minnesota, 55455, United States
2 - University of Minnesota, University of Minnesota, Department of Civil, Environmental, and Geo- Engineering, 122 Civil Engineering Building, 500 Pillsbury Drive SE, Minneapolis, Minnesota, 55455, United States

Contact Information:; 612-625-3098


Highly oxidized chemicals can be reduced by Fe(II) when in the presence of hematite (α-Fe2O3) or goethite (α-FeOOH). These redox reactions are important because they transform organic environmental contaminants and simultaneously alter mineral surfaces. Hematite (α-Fe2O3) is a ubiquitous and stable iron oxide that is found in rocks and sediments in many environmental systems. Aluminum substituted hematite, which is much more common in environmental systems than is pure hematite, was synthesized with varying morphologies and with aluminum substitution ranging from 0 to 2.5 mole percent. The reaction kinetics of the reduction of the model contaminant 4-chloronitrobenzene to 4-chloroaniline in batch reactors containing hematite nanoparticles and Fe(II) were determined using a known HPLC literature method. The change in morphology and composition of the hematite nanoparticles were determined through TEM imaging before and after the reaction. In addition, this study used a column to better model the dynamic flow of contaminated water past the sediments. Columns were packed using a silica sand standard coated with the hematite particles. The presentation will highlight comparisons between experiments varying pH, concentration, flow rate, column packing procedure, and other experimental variables. Results will enable improved predictions regarding the kinetics of reductive degradation of highly oxidized organic contaminants in environments rich in hematite and Fe(II).