Kinetics and efficiency of H2O2 activation by iron-containing minerals and aquifer materials

• Published in: Water research (Oxford) Vol. 46; no. 19; pp. 6454 - 6462
• Main Authors: Pham, Anh Le-Tuan, Doyle, Fiona M., Sedlak, David L.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01-12-2012; Elsevier
• Subjects: Advanced oxidation process; Applied sciences; aquifers; catalysts; coatings; Dissolved silica; Environmental Restoration and Remediation - methods; Exact sciences and technology; Fenton reaction; Ferric Compounds - chemistry; groundwater; Groundwater - chemistry; Groundwater treatment; Hydrogen peroxide; Hydrogen Peroxide - chemistry; Hydrogen-Ion Concentration; Hydroxyl Radical; iron; Iron - chemistry; Iron oxides; Kinetics; manganese; Manganese Compounds - chemistry; manganese oxides; Minerals - chemistry; oxidation; Oxidation-Reduction; Oxides - chemistry; phenol; Phenol - chemistry; Pollution; Silicon Dioxide - chemistry; Soil Pollutants - chemistry; soil remediation; United States; Water Pollutants, Chemical - chemistry; Water treatment and pollution; Fenton reaction; Hydrogen peroxide; Iron oxides; Dissolved silica; Groundwater treatment; Advanced oxidation process; Advanced oxidation processes; Water treatment; Iron oxide; Iron; Soil pollution; Aquifers; Aquifer system; Decontamination; Hydroxyl radicals; Oxidation; Organic compounds; Ground water; Clay; Pollutant behavior; Heavy metal; Persistence; Trace element; Carcinogen; Phenol; Silicon oxides; Phenols; Physicochemical purification; Kinetics; Waste water purification; Catalyst; Manganese
• ISSN: 0043-1354; 1879-2448
• DOI: 10.1016/j.watres.2012.09.020

To gain insight into factors that control H2O2 persistence and OH yield in H2O2-based in situ chemical oxidation systems, the decomposition of H2O2 and transformation of phenol were investigated in the presence of iron-containing minerals and aquifer materials. Under conditions expected during remediation of soil and groundwater, the stoichiometric efficiency, defined as the amount of phenol transformed per mole of H2O2 decomposed, varied from 0.005 to 0.28%. Among the iron-containing minerals, iron oxides were 2–10 times less efficient in transforming phenol than iron-containing clays and synthetic iron-containing catalysts. In both iron-containing mineral and aquifer materials systems, the stoichiometric efficiency was inversely correlated with the rate of H2O2 decomposition. In aquifer materials systems, the stoichiometric efficiency was also inversely correlated with the Mn content, consistent with the fact that the decomposition of H2O2 on manganese oxides does not produce OH. Removal of iron and manganese oxide coatings from the surface of aquifer materials by extraction with citrate–bicarbonate–dithionite slowed the rate of H2O2 decomposition on aquifer materials and increased the stoichiometric efficiency. In addition, the presence of 2 mM of dissolved SiO2 slowed the rate of H2O2 decomposition on aquifer materials by over 80% without affecting the stoichiometric efficiency.
► H2O2 loss and OH production catalyzed by iron-containing solids were studied. ► Solids that were more reactive with H2O2 exhibiting lower OH production. ► Surface iron and manganese oxides are detrimental for OH production. ► Removing ineffective oxides enhanced the OH production efficiency. ► Dissolved silica slowed the rate of H2O2 loss.