Remediation of soils contaminated with methomyl using electrochemically produced gaseous oxidants

• Published in: Chemosphere (Oxford) Vol. 362; p. 142653
• Main Authors: Mirella da Silva, Leticia, Mena, Ismael F., Sáez, Cristina, Motheo, Artur J., Rodrigo, Manuel A.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.08.2024
• Subjects: Chlorine dioxide; Hydrogen peroxide; Ozone; Perforated pipes; Soil remediation; UV light; Soil remediation; Ozone; Hydrogen peroxide; Chlorine dioxide; Perforated pipes; UV light
• ISSN: 0045-6535; 1879-1298; 1879-1298
• DOI: 10.1016/j.chemosphere.2024.142653

This prospective work focuses on the use of two different gaseous oxidants (chlorine dioxide and ozone) to remediate soil polluted with methomyl in two different applications: ex-situ and in-situ. In the first, the soil washing is integrated with the bubbling of the oxidant, while in the second, the gas was introduced by a perforated pipe located sub-superficially. Regarding the soil washing treatment, results demonstrate that direct use of ozone is not very efficient, although an important improvement is obtained following activation with hydrogen peroxide or UV light. In contrast, chlorine dioxide exhibited complete methomyl depletion from the soil, although with higher energy consumption and technical complexity compared to ozone. The direct dosing of the gaseous oxidants in perforated pipes is effective, achieving methomyl removals of 7.8 % and 9.2 % using ozone and chlorine dioxide, respectively. In these cases, soil conditions are not significantly modified, which becomes an important advantage of the technology as compared with other electrochemically assisted soil remediation process, in which large regions of the treated soil are affected by important changes in the pH or by depletion of ions. This lower impact makes these novel technologies more promising for further evaluations. [Display omitted] •High efficiencies in the electrochemical production of ozone and chlorine dioxide.•Gaseous oxidants produced electrochemically suitable for soil treatment.•Integrated soil washing with ClO2 achieves complete removal of methomyl.•Integrated soil washing with ozone results in low removals of methomyl.•Outstanding performance in direct dosing of ClO2 and O3 through perforated pipes.