Preparation and characterization of novel mesoporous chitin blended MoO3-montmorillonite nanocomposite for Cu(II) and Pb(II) immobilization

Abstract

A novel mesoporous chitin blended MoO₃-Montmorillonite nanocomposite was prepared through three-steps synthesis. First, chitin was extracted from prawn shell then MoO₃-MMT was prepared, and lastly, chitin was blended with MoO₃-MMT. Chitin-MoO₃-MMT was applied for the removal of Cu(II) and Pb(II) from wastewater. XRD characterization revealed MoO₃ solubility in MMT interlayers, SEM showed a nanocomposite formation with sharp nanorods like-structure and length ranging from 60 to 77.7 nm. FTIR exhibited fundamental changes in the surface functional groups after adsorption. XPS analysis before and after adsorption showed the domination of chemical bonding with N and O. N₂ adsorption-desorption isotherm displayed H₃-type hysteresis loop and a pore size diameter of 10.67 nm confirming the mesoporous nature. Adsorption efficiency was studied as a function of pH, time, metal concentration and adsorbent mass. Adsorption capacity (Q_e) values were 19.03 and 15.92 mg.g^-1 for Cu(II) and Pb(II) respectively. The metal surface coverage mapping was 1.87 × 10^¹⁹ and 4.34 × 10^¹⁸ atoms/m² for Cu(II) and Pb(II) respectively. Adsorption followed Langmuir isotherm and pseudo-second-order (PSO) kinetics suggesting a monolayer chemisorption domination. Intraparticle diffusion (IPD) model showed a boundary layer control. Thermodynamically, the adsorption was spontaneous and endothermic with activation energies 25.94 and 29.37 kJ.mol^-1 for Cu(II) and Pb(II) respectively.

Keywords: ANOVA statistical analysis; Adsorption surface mapping; Chitin-MoO(3)-MMT nanocomposite; Isotherm; Kinetics; Metal adsorption; Thermodynamics.