Efficient lead ion removal from aqueous solutions for wastewater treatment using a novel cross-linked alginate-rice husk ash-graphene oxide-chitosan nanocomposite

This research introduces an innovative composite, the cross-linked alginate-rice husk ash-graphene oxide-chitosan nanoparticles (CL-ARCG-CNP), designed for the effective adsorption of lead ions (Pb²⁺) in water treatment applications. Comprehensive characterization was performed using techniques such as Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), High-Resolution Transmission Electron Microscopy (HR TEM), Selected Area Electron Diffraction (SAED), Atomic Force Microscopy (AFM), Thermogravimetric Analysis (TGA), and Brunauer-Emmett-Teller (BET) analysis. These analyses revealed notable structural and morphological features. The CL-ARCG-CNP composite demonstrated a significant surface area of approximately 148.44 m²/g, achieving an impressive adsorption capacity of 242.5 mg/g and a removal efficiency of 95.2 % after 240 min of contact duration. The adsorption process conformed to the Freundlich isotherm model (R²: 0.998) and the pseudo-second-order kinetic model (R²: 0.9992). Thermodynamic studies confirmed the spontaneity and endothermic nature of the adsorption process. Reusability tests showed that the composite could be reused for up to five cycles with minimal loss in adsorption capacity. These findings indicate that the CL-ARCG-CNP composite is highly effective for the removal of Pb²⁺ ions from aqueous solutions, making it a promising material for wastewater treatment.