Detoxification of Chlorinated Dioxins and Furans in Soils via One-Step, Self-Sustaining Smoldering

Abstract Conventional thermal treatment of halogenated persistent organic pollutants requires energy input and promotes chlorinated byproducts during heating or cooling. Self-sustaining smoldering provides a heat-efficient thermochemical route for dehalogenation in porous soils, but its effectiveness for soils contaminated with polychlorinated dibenzo-p-dioxins/furans (PCDD/Fs) and the mechanistic basis of detoxification remain insufficiently defined. Here, we demonstrate one-step smoldering treatment of PCDD/Fs across bench-scale operating windows, congener-resolved tests, multiple contamination scenarios, and 100 kg pilot-scale validation. The process achieved high toxic equivalency (TEQ) removal, suppressed chlorobenzene formation, and limited gas-phase dioxin transfer to less than 3%. Congener profiles, phase-resolved chlorine redistribution, mineral characterization, ReaxFF molecular dynamics, and density functional theory support stepwise dechlorination and framework cleavage under a moderately reductive, mineral-influenced smoldering environment. Pilot-scale tests achieved up to 98% TEQ removal in heated bed zones with an energy demand lower than that of conventional thermal treatment. This work advances smoldering as a scalable, low-carbon detoxification strategy for organohalogen-contaminated soils.