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

Abstract

A highly mesoporous SiO2-chitin supported MoO3 nanocomposite was synthesized and characterized for immobilizing Pb(II) and Cu(II) from water. This composite combines MoO3 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 m2/g), pore volume (0.48 cm3/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 MoO3 nanoparticles in an amorphous SiO2-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.