Breakthrough in soil remediation advancement: Nonthermal plasma powers polyvalent Ce-Mn (Hydro)oxide-enhanced nanographene to securely stabilize thallium-laden soils

The urgent need for remediation of thallium (Tl)-contaminated soils arises from its widespread presence as a poisonous heavy metal (HM), coupled with numerous challenges such as high costs, long durations, secondary pollution risks, and technological limitations. In the study, a novel approach has been introduced to the remediation of Tl-contaminated soils using calcium sulphoaluminate cement. This innovation involves the employment of nonthermal plasma-irradiated polyvalent Ce-Mn (hydro)oxide-modified nanographene (NTP-P-Ce-Mn-NGs) to intensify the cementation and immobilization of Tl species. The chemical speciation of Tl contaminants influenced by the dosage of NTP-P-Ce-Mn-NGs in the cementation was measured to explore the potential enhancement mechanisms brought by NTP-P-Ce-Mn-NGs in the sulphoaluminate cementation. Comprehensive strategies were adopted to explore the reaction pathways. In orthogonal (OD) experiments, compressive strengths ranging from 22.14 to 56.78 MPa in sulphoaluminate-cemented cubes were achieved. Remarkably, when NTP-P-Ce-Mn-NGs were introduced, the leached Tl concentration was reduced to 0.21–21.46 µg/L. This significant reduction was attributed to the NTP-P-Ce-Mn-NGs-induced more uniform hydration reactions and a more holistic microstructure. The presence of diverse valent Ce and Mn species within the matrix was confirmed, revealing a reliable interaction between NTP-irradiated high-valent Mn and Ce with monovalent Tl ions. This interaction induced multiple redox reactions, immobilizing Tl contaminants within the matrix and the cementation encapsulation. This study represents a significant milestone in Tl pollution control, paving the way for more efficient and cost-effective soil remediation strategies.