Sustainable and cost-effective fabrication of kaolinite/MoS2 nanocomposite for enhanced uranium sorption: Experimental and mathematical modeling insights

A Kaolinite-based molybdenum disulfide nanocomposite (KMS) was synthesized as an efficient sorbent for U(VI) removal. Structural and surface characterization (FTIR, XRD, SEM-EDX, BET, HR-TEM) confirmed KMS’s mesoporous nature, with enhanced surface area (33.15 m2/g) and pore volume (0.051 cm3/g) compared to reduced MoS₂ (16.23 m2/g, 0.034 cm3/g). At optimal conditions (pH 4.5, 25 ◦C, 60 min, 0.5 g/L), KMS achieved a maximum U(VI) sorption capacity of 0.748 mmol/g, surpassing pristine MoS₂ (0.486 mmol/g at 90 min), aligning with HSAB principles and physicochemical synergies. Kaolinite’s multifunctional role was critical: (1) its Al–OH/Si–OH groups facilitated electrostatic attraction and inner-sphere coordination with U(VI) species (e.g.,
UO₂(SO₄)₂2− ), (2) –Si–O– defects enabled ion exchange (EDX-verified Na+/H+ replacement), and (3) Al3+ stabilized sulfur vacancies in amorphous MoS2, amplifying defect-driven U(VI) binding. Sorption increased with temperature (0.843 mmol/g for KMS, 0.550 mmol/g for MoS₂ at 45 ◦C), adhering to Langmuir/Sips isotherms and pseudo-first-order kinetics, with thermodynamic spontaneity (ΔG◦ < 0) and endothermicity (ΔH◦ > 0). The Freundlich model showed inferior consistency, underscoring monolayer dominance. Regeneration with 0.25 M HCl/NaHCO₃ retained >90 % efficiency over 5 cycles. Finally, an AI-powered 3D nonlinear model quantified U (VI) sorption dynamics, validating KMS’s superior performance. This work highlights kaolinite’s active role in
enhancing MoS2’s adsorption via structural dispersion, defect engineering, and synergistic interactions, offering a scalable strategy for uranium recovery.