Oxygen atmosphere enhances ball milling remediation of petroleum-contaminated soil and reuse as adsorptive/catalytic materials for wastewater treatment

Abstract

Ball milling is an environmentally friendly technology for the remediation of petroleum-contaminated soil (PCS), but the cleanup of organic pollutants requires a long time, and the post-remediation soil needs an economically viable disposal/reuse strategy due to its vast volume. The present paper develops a ball milling process under oxygen atmosphere to enhance PCS remediation and reuse the obtained carbonized soil (BCS-O) as wastewater treatment materials. The total petroleum hydrocarbon removal rates by ball milling under vacuum, air, and oxygen atmospheres are 39.83%, 55.21%, and 93.84%, respectively. The Langmuir and pseudo second-order models satisfactorily describe the adsorption capacity and behavior of BCS-O for transition metals. The Cu2+, Ni2+, and Mn2+ adsorbed onto BCS-O were mainly bound to metal carbonates and metal oxides. Furthermore, BCS-O can effectively activate persulfate (PDS) oxidation to degrade aniline, while BCS-O loaded with transition metal (BCS-O-Me) shows better activation efficiency and reusability. BCS-O and BCS-O-Me activated PDS oxidation systems are dominated by 1O2 oxidation and electron transfer. The main active sites are oxygen-containing functional groups, vacancy defects, and graphitized carbon. The oxygen-containing functional groups and vacancy defects primarily activate PDS to generate 1O2 and attack aniline. Graphitized carbon promotes aniline degradation by accelerating electron transfer. The paper develops an innovative strategy to simultaneously realize efficient remediation of PCS and sequential reuse of the post-remediation soil.