Pyrogenic Materials-Induced Immobilization of Eu in Aquatic and Soil Systems: Comparative Study

Pyrogenic materials produced from various input materials and with valuable characteristics such as high porosity, extensive surface area, and mineral composition represent alternative to traditional carbon-based materials in area of contaminant immobilization, aqueous solutions purification, and soil remediation. Intensification of industry and technological processes brings increased use of lanthanides and thus potential risk of lanthanide penetration into soil and aquatic systems. This study examined the roles of three different pyrogenic materials: microcrystalline cellulose-derived pyrogenic materials (MCPM), organic cotton-derived pyrogenic material (OCPM), and sewage sludge-derived pyrogenic material (SSPM) produced in the process of slow pyrolysis at 430 °C in N₂ atmosphere as potential Eu immobilization and sorption materials. Produced materials were characterized by determination of wide range physicochemical properties via elemental analysis, SEM, FT-IR, and sorption potential for Eu in batch sorption experiments. The obtained data confirmed that sorption separation of Eu by OCPM, MCPM, and SSPM from aqueous solution is relatively rapid process with reached equilibrium at 24 h. Batch equilibrium experiments revealed maximum sorption capacities 0.602 mg g⁻¹ for MCPM, 1.761 mg g⁻¹ for OCPM, and 2.586 mg g⁻¹ for SSPM. The presence of co-ions such as Al in system reduced sorption potential about more than 50% for all three studied materials. Column leaching test with artificially contaminated soil and 5% (w/w) amendments of pyrogenic materials showed significant retention ability of MCPM, OCPM, and SSPM for mobile Eu forms compared to control soil. Pyrolysis production of pyrogenic materials and their applications as an effective immobilization and separation tools for wide range of xenobiotics can be innovative method in environmental management and waste assessment.