Principles and application of sodium percarbonate in soil and groundwater remediation by in situ chemical oxidation

Abstract

Sodium percarbonate (SPC) is an oxidizing agent that has been recently applied in soil and groundwater remediation. Even if it is a hydrogen peroxide-based compound with the potential to degrade a wide variety of contaminants, SPC is still relatively little known and studied. This study presents a review of SPC main properties, chemical reactions and factors that interfere in its application in environmental remediation. Several studies were compiled to gather information about reactions with different types of contaminants, dosages, use of activators and chelating agents. SPC is capable of efficiently degrading some aromatic hydrocarbons, including benzene, polycyclic aromatic hydrocarbons, and chlorinated solvents, among others. The use of activators enables a faster and more intense generation of hydroxyl radicals. Other reactive oxygen species, such as hydroperoxyl radicals and the superoxide anion, are also formed and aid the degradation of contaminants, despite not having the same oxidation potential of the hydroxyl radical. Different activators are mentioned in the literature, such as Fe(II) and Fe(III). The use of chelating agents, mainly citric acid, oxalic acid and EDDS (ethylenediamine-N,N’-disuccinic acid – C₁₀H₁₆N₂O₈), also improves the oxidation efficiency. However, the analysis of the published data makes it evident that the conditions for obtaining good results are extremely dependent on specific site conditions, such as dissolved ions, presence of organic matter and interactions with different minerals. Moreover, there is a limited amount of information about the interaction of PCS with different minerals and soils.