Application of Chelating Agents to Enhance Fenton Process in Soil Remediation: A Review

Abstract

Persistent organic contaminants affecting soil and groundwater pose a significant threat to ecosystems and human health. Fenton oxidation is an efficient treatment for removing these pollutants in the aqueous phase at acidic pH. However, the in-situ application of this technology for soil remediation (where pHs around neutrality are required) presents important limitations, such as catalyst (iron) availability and oxidant (H2O2) stability. The addition of chelating agents (CAs), forming complexes with Fe and enabling Fenton reactions under these conditions, so-called chelate-modified Fenton process (MF), tries to overcome the challenges identified in conventional Fenton. Despite the growing interest in this technology, there is not yet a critical review compiling the information needed for its real application. The advantages and drawbacks of MF must be clarified, and the recent achievements should be shared with the scientific community. This review provides a general overview of the application of CAs to enhance the Fenton process for the remediation of soils polluted with the most common organic contaminants, especially for a deep understanding of the activation mechanisms and influential factors. The existing shortcomings and research needs have been highlighted. Finally, future research perspectives on the use of CAs in MF and recommendations have been provided.

Phyto-Fenton remediation of a dichloro-diphenyl-trichloroethane contaminated site in Ha Tinh Province, Vietnam

“…The conventional Fenton process displays its maximum · OH production and subsequent pollutant oxidation activity in an acidic pH in the range of 2.8–3.5 30 , 31 . This pH medium, resulting in the use of strong sulphuric acid with ferrous and ferric catalysts and hydrogen peroxide, led to a degraded soil and microorganism community after treatment.…”

“…This again suggests that NA-COS and COS-Y chitin- and chitosan-oligosaccharides, respectively, might not work as effectively as expected for the elicitors for oxidative burst in vetivers. Therefore, further studies on the application of oxidative bursts and effective elicitors should be conducted 30 .…”

Recent Developments in Advanced Oxidation Processes for Organics-Polluted Soil Reclamation

“…However, it was not applied as a remediation process to degrade organics in aqueous solution until the late 1960s [15], and the use of this treatment for the removal of organics from soils was first evidenced in the 1990s [16]. However, at present it is the most common process for soil remediation [17].…”

Radio‐fluorogenic nanoclay gel dosimeters with reduced linear energy transfer dependence for carbon‐ion beam radiotherapy

“…Further clarification of the effects of radiation and the addition of pyridine on the LET will be performed in future work. Several prior studies 49,[57][58][59] demonstrated that the use of pyridine increases the rate of Fenton-like reactions via the formation of a complex. Consequently, we consider that the addition of pyridine does not affect the H 2 O 2 decomposition reaction with Fe 3+ , meaning that the sensitizing effect of H 2 O 2 on the dosimeter reduces the effect of LET.…”