Zeynep Mine Şenol, Selçuk Şimşek
A novel polyacrylamide@vermiculite/lignin (PAA@VL) ternary composite was synthesized for the removal of UO22+ ions from aqueous solutions. FT-IR and SEM-EDX analyses confirmed the functional groups, heterogeneous layered morphology, and successful UO22+ adsorption of the composite. Bulk experiments showed that the adsorption process was affected by pH, initial concentration, dosage, temperature, and contact time. Isotherm studies showed that Langmuir and Freundlich models described the process well and that the maximum adsorption capacity was 2.15 mol kg-1. The high UO22+ removal performance of PAA@VL is attributed to the synergistic effect of its components, the abundant adsorptive sites, and a strong affinity for UO22+ ions. Thermodynamic findings indicate that a negative Gibbs energy (ΔG° = -55.0-54.4 kJ mol-1) suggests the adsorption process is spontaneous, a negative entropy change (ΔS° = -16.8 J mol-1 K-1) indicates a reduction in surface disorder on the composite, and a negative enthalpy value (ΔH° = -59.7 kJ mol-1) suggests the adsorption process is exothermic. The PAA@VL ternary composite shows strong potential as an efficient and sustainable adsorbent for UO22+ removal.