From efficient remediation to valorization: Activating endogenous environmental functions of carbonized soils derived from petroleum-contaminated soils by pyrolysis and ball milling

Convert PCS into Si-CS with effective adsorption/catalytic properties. • Si-CS exposes more carbonate and metal oxides to adsorb heavy metals. • Si-CS produces more sites to activate PMS and produce reactive oxygen. • Si-CS generates more graphitic carbon to accelerate direct electron transfer. • The ROS exposure in the Si-CS/PMS system was quantified. Petroleum-contaminated soil (PCS) can be effectively remediated via pyrolysis, yielding a mineral/carbon composite; however, its resource recovery remains insufficiently explored. This study proposes a combined process involving ball milling with natural silica sand as additive followed by oxygen-limited pyrolysis to convert PCS into carbonized soil for reuse as a wastewater treatment material, with theoretical maximum adsorption capacities of 1338.88, 293.97, 125.20, and 58.75 mg/g for lead, copper, zinc, and cadmium, respectively. The material can also effectively activate peroxymonosulfate (PMS) oxidation to generate reactive species—including sulfate radicals, hydroxyl radicals, and singlet oxygen—enabling dual degradation pathways for organic pollutants through both radical and non-radical mechanisms. The combined treatment exposes more functional components (carbonates, metal oxides, and solid carbon including amorphous and graphitic carbon) on the surface, enhancing reactivity and significantly improving adsorption and catalytic performance. This environmentally sustainable strategy utilizes resource recovery to offset remediation costs, demonstrating strong practical potential. Download: Download high-res image (122KB) Download: Download full-size image