The role of soil organic matters and minerals on hydrogen peroxide decomposition in the soil

Application of H2O2 in in-situ chemical oxidation (ISCO) for soil remediation has been limited by its rapid decomposition. However, effect of main factors involving in this phenomenon are not well understood. In this contribution, H2O2 decomposition in the six types of natural soils was investigated by kinetic analyses and soil characterizations. The grassland soil (GS) and red soil (RS) have the highest H2O2 decomposition rates (respective 0.048 and 0.069 min(-1)), while the paddy soil (PS) shows the lowest one (0.004 min(-1)). The decomposition mainly takes place on the surface adsorption sites of soil particles. PS has the highest content of SOM, which can block the active adsorption sites for H2O2 decomposition. The effects of dissolved organic matter (DOM) and biological debris in the soil are minor. Iron and manganese containing minerals are significantly influential on H2O2 decomposition, and the soil with a higher content of clay can induce faster H2O2 decomposition. The immobilized goethite (GM) and birnessite (BM) on montmorillonite were synthesized to simulate soil minerals. Results show H2O2 decomposition rates in BM is even faster than GM when the former dosage is two orders of magnitude lower than that of the latter. This indicates the crucial role of manganese minerals although their contents are generally much lower than that of iron in the soils. This study advanced the understanding of H2O2 decomposition in the soil and bring insights for H2O2 based ISCO technology in soil remediation. (C) 2020 Elsevier Ltd. All rights reserved.