Regulating soil polarity to achieve efficient Fenton direct oxidation of total petroleum hydrocarbons in soil

• Published in: Journal of environmental chemical engineering Vol. 13; no. 2; p. 115984
• Main Authors: Xu, Jinlan, Dai, Jianan, Cao, Zezhuang, Liu, Chuanyu, Li, Yikai, Gao, Mengzhen, Guan, Huiwen, Zhou, Rankang
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.04.2025
• Subjects: Fenton direct oxidation; Hydrophilic functional groups; Hydroxyl radical transfer; Petroleum hydrocarbon soils; Soil polarity regulation; Fenton direct oxidation; Soil polarity regulation; Petroleum hydrocarbon soils; Hydroxyl radical transfer; Hydrophilic functional groups
• ISSN: 2213-3437
• DOI: 10.1016/j.jece.2025.115984

The transfer of hydroxyl radicals (·OH) from the liquid phase to the soil is anticipated to enhance the efficient direct oxidation of total petroleum hydrocarbons (TPHs) in the soil. Based on the polar/non-polar interactions of polymers in aqueous solutions, polar chitosan was used to chelate Fe2 +, which was then thoroughly mixed with soil contaminated by non-polar petroleum hydrocarbons. This process aims to regulate the soil's polarity to facilitate the transfer of hydroxyl radicals. Soil polarity, defined as η (η = the total integrated area of hydrophilic functional groups/the proportion of humic acid-like components), was found to influence the oxidation process significantly. The results indicate that the maximum oxidation capacity of TPHs in the soil reached 6220.20 mg/kg. The values represent increases of 1.19 times compared to traditional Fenton technology. Excitation Emission Matrix Spectra(3DEEM) revealed that the proportion of hydrophilic organic components increased to 85.77 % following polarity regulation. FT-IR demonstrated an increase in the quantities of hydrophilic functional groups, including O-H (112.92), C-O (74.46), and CO (14.89). The enhancement of these hydrophilic components contributed to an increase in soil polarity, which facilitated the transfer of ·OH from the liquid phase to the soil. Additionally, the ·OH transfer amount of 0.12 × 10−2 a.u. resulted in an increase of 1032.62 mg/kg in the oxidation of TPHs. A positive correlation between soil polarity and the oxidation of TPHs was observed, indicating that increased soil polarity can promote the direct oxidation of TPHs in the soil. [Display omitted] •The oxidation amount of TPHs was 6220.20 mg/kg after polarity regulation.•Tydrophilic organic and functional groups increased after polarity regulation.•Increased soil polarity promotes the transfer of ·OH from liquid to the soil.•OH transfer 0.35 × 10−2 ·OH enhances oxidation of 1032.62 mg/kg of TPHs.