Selective adsorption of Sr2+ over Cs+ on magnetic zeolite P-A from lithium porcelain clay tailings: A combined experimental and DFT study

Selective separation of 90 Sr 2+ and 137 Cs + from nuclear wastewater is a significant challenge in the field of environmental remediation. In this paper, magnetic P-type zeolite composites loaded with Fe 3 O 4 were successfully synthesized via an alkali fusion-assisted hydrothermal method using lithium porcelain clay tailings (LPCT) as the silicon-aluminum source, achieving resource utilization of solid waste. The material exhibited excellent selective adsorption capacity for Sr 2+ : under the conditions of pH = 6 and a dosage of 2 g/L, the removal rate for Sr 2+ (100 mg/L) reached 99.4%, while that for Cs + (50 mg/L) was only 55.2%. In simulated/real seawater systems, the material maintained exceptionally high selectivity for trace Sr 2+ (with a K d value of 1.265 L·g –1 in simulated seawater). Mechanistic studies revealed that Sr 2+ undergoes specific ion exchange primarily by substituting Na + within the zeolite framework (adsorption energy: −2.37 eV), forming stable chemical bonds; in contrast, Cs + binds only through weak physical adsorption (adsorption energy: −0.85 eV), making it susceptible to displacement by competing ions. After five cycles, the Sr 2+ removal rate remained above 65%. This study presents a strategy for upcycling solid waste into high-performance functional materials and offers a promising solution for the efficient and selective separation of radioactive Sr 2+ from complex aqueous environments, highlighting its potential for practical nuclear wastewater treatment.