Fenton technology optimization for polycyclic aromatic hydrocarbons degradation in soil

Abstract

An effective Fenton oxidation technology was developed to degrade PAHs in the soil, and fluorene (FLU), phenanthrene (PHE), fluoranthene (FLA) and pyrene (PYR) were selected as primary pollutants. This research presented a systematic approach to optimize the key operational parameters, such as reaction time, H₂O₂ concentration, Fe²⁺/H₂O₂ addition ratio, pH value, and soil-water ratio, those factors altogether affected the generation of ^•OH and the overall degradation efficiency of PAHs. The optimized parameter combination of Fenton technology suitable for PAHs degradation in complex soil environments was proposed. The key parameters were as follows: soil-water ratio was 2:1, pH was 3, H₂O₂ concentration was 11 % of the total system, Fe²⁺/H₂O₂ addition ratio was 1/8, and reaction time was 24 h. The degradation percentages for FLU, PHE, FLA and PYR were 75.4 %, 66.2 %, 60.8 % and 93.7 % in this optimized system, respectively. As the reaction time increased, the degradation efficiency of PAHs by Fenton technology reached the maximum until it became stable or slightly decreased. Appropriate H₂O₂ concentration and Fe²⁺/H₂O₂ addition ratio were conducive to the maximum generation of ^•OH, thus improving the degradation efficiency of PAHs. The pH value significantly influenced the degradation of PAHs, and the soil-water ratio had important effects on the Fenton oxidation process. By optimizing these conditions, a more thorough and profound assessment of the Fenton technology's applicability in treating actual-world PAHs-polluted soils was achievable, and it was expected to reduce the restoration cost. Meanwhile, it also contributed to the development of more efficient and sustainable soil remediation strategies.