Mesoporous SiO2-chitin/MoO3 Nanocomposite: Synthesis, Surface Investigation, Uptake Potential for Pb(II) and Cu(II), and Future Outlook

A highly mesoporous SiO ₂ -chitin supported MoO ₃ nanocomposite was synthesized and characterized for immobilizing Pb(II) and Cu(II) from water. This composite combines MoO ₃ for interactions, chitin for chelation, and silica for stability. XPS and FTIR and zeta potential investigations showed alterations in binding energies, metal-oxygen coordination bonds and surface charge highlighting an interplay in the removal mechanism between electrostatic attraction and surface complexation. The composite's features include a high surface area (266.95 m ² /g), pore volume (0.48 cm ³ /g), and well-defined mesoporous structure (mean pore diameter: 7.192 nm). S-TEM confirmed uniform distribution of Si, O, and Mo with localized Mo concentration. XRD confirmed well-crystallized MoO ₃ nanoparticles in an amorphous SiO ₂ -chitin matrix. Metal removal was affected by pH, time, concentration, and dose. Kinetics followed a pseudo-second-order model, with intraparticle diffusion and multilayer heterogeneous adsorption per Freundlich isotherm. Langmuir capacities were 16.05 mg/g for Cu(II) and 27.30 mg/g for Pb(II). Thermodynamic data suggested endothermic, spontaneous adsorption with stronger Pb(II) affinity. Activation energy values (Cu(II): 15.36 kJ/mol, Pb(II): 20.48 kJ/mol) supported chemisorption as the primary mechanism. The study highlights the nanocomposite's potential for Cu(II) and Pb(II) removal.