Chitosan functionalized recyclable and eco-friendly nanoadsorbent for Pb(II) adsorption from water

In the present study, MnO2 nanoparticles were synthesized using Citrus limetta peels extract and functionalized by chitosan polymer. Surface morphology analysis of chitosan functionalized MnO2 nanoparticles was carried out using a scanning electron microscope (SEM) and transmission electron microscope (TEM), which revealed that the synthesized nanoparticles were spherical, with a size range of 14–24 nm. Energy dispersive X-ray analysis and elemental mapping were used to observe Mn, O, C, H, and N. Fourier-transform infrared spectroscopy confirmed the presence of hydroxyl, carboxyl, and amino groups on the surface of the nanoparticles. The kinetics and isotherms were compared and it was found that the pseudo-second-order and Langmuir isotherm were the best fit, with R2 values of 0.99. The thermodynamic study demonstrated that the adsorption was endothermic and spontaneous. These findings indicate that chitosan functionalized nanoparticles have a better Pb(II) removal efficiency (94.40%), making them an eco-friendly and cost-effective alternative for wastewater treatment.