Adsorption performance and mechanism of hierarchical LTA zeolite for Cs⁺ in aqueous

Radioactive wastewater discharge increased continuously with the widespread utilization of nuclear energy around the world, among which 137 Cs is one of the most critical radionuclides requiring removal. Traditional Lind Type A (LTA) zeolite exhibits promising adsorption potential for ¹³⁷Cs, however its slow adsorption kinetics remains a limitation. A hierarchically porous LTA zeolite (JLTA) via modification with Dimethyl Diallyl Ammonium Chloride (DMDAAC) was developed. Mesopores of JLTA were constructed effectively via hydrophobic groups of DMDAAC while preserving its intrinsic micropores, which was confirmed by XRD, SEM-EDS, BET, and FT-IR. Optimal conditions of JLTA’s adsorption performance (pH = 6, dosage = 5 g/L, T = 298 K) was gained during systematic investigations under varying pH, dosage, contact time, initial Cs⁺ concentration, and temperature. Cs⁺ adsorption by JLTA was primarily due to ion exchange with supplementary electrostatic attraction, following monolayer adsorption, which was revealed via kinetic models, adsorption isotherms, and characterization analyses. The intra-particle diffusion-controlled process achieved equilibrium within 5 min, demonstrating remarkably accelerated kinetics. A maximum adsorption capacity of 249.390 mg/g of JLTA was exhibited.