Integrating ZnO/Ag ₂ O@g‐C ₃ N ₄ ‐Based Nanocomposites Into a Carrageenan Matrix to Efficiently Remove Heavy Metals From Water

ABSTRACT This research focused on characterizing graphitic carbon nitride (g‐C ₃ N ₄ ) nanocomposites incorporated with ZnO and Ag ₂ O nanoparticles, and carrageenan to remove heavy metals. The ZnO/Ag ₂ O@ g‐C ₃ N ₄ and ZnO/Ag ₂ O/g‐C ₃ N ₄ @Carr nanocomposites demonstrated thermal stability of 97.40% (108.81°C) and 82.80% (188.99°C) for TGA. This suggested that the nanocomposites retained structural integrity even under varying temperature conditions, making them suitable for applications in wastewater treatment. BET showed that the surface area of the nanocomposites followed the order of Ag ₂ O (376 02 m ² /g) > ZnO (2954 m ² /g) > GA (1645 m ² /g) > GZ (1619 m ² /g) > g‐C ₃ N ₄ (485 m ² /g), indicating enhanced the surface area of the modified g‐C ₃ N ₄ . All nanocomposites were mesoporous with Type IV isotherms and H ₃ hysteresis loops. The increased surface area and pore volume, particularly in carrageenan‐modified g‐C ₃ N ₄ nanocomposirtes, had improved metal removal performance. Furthermore, the nanocomposites exhibited hierarchical pore structures consisting of interconnected micropores and mesopores. These nanocomposites exhibited a high capacity to adsorb heavy metals, demonstrating an adsorption efficiency of over 90% (carrageenan nanocomposites), and 70% (without carrageenan), due to the higher electronegativity and stronger electrostatic interactions between the heavy metals and nanocomposites. The adsorption process followed the Freundlich isotherm and pseudo‐second‐order kinetics, indicating stable and efficient nanocomposites to remove heavy metals.