Green Synthesis Of Silver Doped Cadmium Oxide Nanocomposites Using Ocimum Lamiifolium (Damakese) Leaf Crude Extract For Chromium Removal From Industrial Wastewater

Abstract

Heavy metal contamination in water poses significant ecological and health risks, necessitating effective removal methods. This study reports the green synthesis of CdO nanoparticles (NPs) and Ag-CdO nanocomposites (NCs), characterized by XRD, FTIR, SEM, zeta potential, and UV-Vis spectroscopy. The optimal adsorption conditions were 0.1 g/100 mL adsorbent dose, pH 2, initial Cr(VI) concentration of 10 mg/L, 25°C temperature, and 5-minute contact time. Under these conditions, Ag-CdO NCs achieved a removal efficiency of 99.6 ± 0.31%, surpassing CdO NPs (96.72 ± 0.27%). The adsorption capacity of Ag-CdO NCs was 87.95 mg/g, with isotherm data fitting well to Freundlich (R²=0.991) and Langmuir (R²=0.898) models. Kinetic studies aligned with a second-order model (R²=0.9994). The separation factor (RL) values is 0.0493 which is below 1 indicated favorable adsorption. The enhanced performance of Ag-CdO NCs is attributed to lower band energy (1.84 eV), increased surface area, and synergistic semiconducting properties compared to CdO NPs (2.73 eV). Overall, Ag-CdO NCs demonstrate high potential as efficient adsorbents for hexavalent chromium removal from industrial wastewater