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

• A novel modification of highly crystalline LTA zeolite with dimethyldiallylammonium chloride significantly enhances Cs⁺ adsorption from aqueous solution. • The modified LTA zeolite achieves adsorption equilibrium within just 5 min while maintaining its original adsorption capacity. • The allyl groups in dimethyldiallylammonium chloride are identified as the key functional groups responsible for the enhanced Cs⁺ uptake. • Adsorption proceeds via a synergistic mechanism combining electrostatic attraction and ion exchange. 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.