Sustainable Remediation of Dibenzofuran-Contaminated Soil by Low-Temperature Thermal Desorption: Robust Decontamination and Carbon Neutralization.

Thermal desorption (TD) is generally considered to be an effective but unsustainable technology. Decontami-nation performance, charring behaviors and physicochemical properties during TD of dibenzofuran-contaminated soil (DCS) are explored. After treatment at 300 degrees C for 20 min, the dibenzofuran concentration decreases from 3969.37 mg/kg to 17.29 mg/kg, lower than Chinese risk screening value. More than 99% of dibenzofuran in soil are removed at low temperature of 300 degrees C, meanwhile the organic carbon is partially retained in soil. Removal mechanism of DCS at 300 degrees C is proposed, including desorption, cracking, and charring. Char material of low H:C ratio is produced by the generation, polymerization and dehydrogenation of aromatic intermediates, and then increases carbon stocks and reduces the carbon footprint of contaminated soil. Mean-while, due to the char generated, pH, cation exchange capacity and specific surface area of DCS heated at 300 degrees C are higher than those of raw DCS, promoting ecological restoration and enhancing carbon sink in soil ecosystems. The aforesaid saving energy, reducing carbon footprint and enhancing carbon sink are exactly the main inno-vative technologies for achieving carbon neutrality. Hence, it may be a contribution to climate change mitiga-tion, in addition to a robust and sustainable remediation of organic contaminated soil.