Efficient remediation of PBDEs in soil by combined chemical leaching and electron beam irradiation

Polybrominated diphenyl ethers (PBDEs) are highly hydrophobic and environmentally persistent, leading to their accumulation in soils and posing serious risks to ecosystems and human health. This study developed an efficient remediation strategy through the synergistic integration of chemical leaching and electron beam (EB) irradiation for treating PBDEs-contaminated soils. EB irradiation alone could directly degrade PBDEs in soil, while a combination with methanol extraction enhanced the process. Methanol effectively extracted BDE47 from soil with an efficiency exceeding 99 % and BDE47 in methanol was degraded rapidly under EB irradiation, achieving complete debromination at a dose of 12 kGy. The leaching agent exhibited excellent reusability over five consecutive cycles, with both extraction and debromination efficiencies remaining consistently high. Moreover, this method demonstrated broad applicability by effectively degrading multiple PBDE congeners. Mechanism studies through ESR and deuterated solvent experiments revealed that electron transfer is the rate-determining step in PBDE degradation, and the debromination rate was independent of the number and position of bromine substituents. This capability represents a significant advantage of EB irradiation over conventional reductive degradation techniques, enabling complete debromination of various PBDEs. This work presents a green and sustainable technology for the remediation of PBDE-contaminated sites, offering significant environmental benefits and promising practical prospects.