Effective remediation of benzo [a] anthracene contaminated soil by combination of low-temperature thermal desorption and advanced oxidation

Abstract

Benzo [a] anthracene (BaA), a highly toxic tetracyclic polycyclic aromatic hydrocarbon, is frequently detected in soils world widely. Traditional high-temperature thermal desorption and unactivated advanced oxidation process (AOP) are either energy-intensive or inefficient due to slow pollutant degradation. This study presented an innovative and effective remediation approach for BaA contaminated soil by combining low-temperature thermal desorption with AOP. The combined method utilizes heat from low-temperature thermal desorption to activate sodium persulfate, thereby enhancing BaA degradation. The results demonstrated that the combined low-temperature thermal desorption and AOP achieved an impressive BaA removal efficiency of up to 92.7 % at 60 °C and 90 °C, surpassing the efficiency of individual treatments. The primary reactive oxygen species responsible for BaA degradation were identified as sulfate radicals and hydroxyl radicals with both contributing nearly equally to the process. The study identified the intermediates formed during BaA degradation and proposed a degradation pathway. The intermediates had lower boiling points and reduced toxicity compared to BaA, indicating the mineralization process was effective in reducing environmental risks. Additionally, the addition of 3 mL methanol improved BaA removal efficiency to 62.2 % from 41.9 % in the control group without methanol, indicating the addition of methanol in AOP significantly improved BaA removal by enhancing desorption from soil particles. This research underscores the potential of the combined low-temperature thermal desorption and AOP as a sustainable, energy-efficient, and cost-effective remediation technology for soils contaminated with polycyclic aromatic hydrocarbons, offering a promising solution for soil remediation.