Synthesis of a Novel Activated Carbon/ZnO Nanocomposite from the Dead Bark of Indian Jujube for Efficient Removal of Cationic Dye Pollutant

In this study, a novel activated carbon/zinc oxide (AC/ZnO) nanocomposite was synthesized from the dead bark of Ziziphus mauritiana (Indian jujube) using chemical activation and high-temperature treatment. The nanocomposite was characterized using FTIR, XRD, BET, FESEM, TEM, XPS, and zeta potential analyses, which confirmed its porous structure and ZnO incorporation. Batch adsorption experiments were conducted to evaluate the ability of the adsorbent to remove toluidine blue (TB) dye from aqueous solutions. Under optimized conditions (0.04 g of adsorbent in 100 mL of dye solution at pH 11.5, a contact time of 50 min, and 25 ± 2°C), the nanocomposite achieved a maximum removal efficiency of 99.6% and an adsorption capacity of 49.9 mg.g⁻¹. The adsorption process followed the Langmuir isotherm model and pseudo-second-order kinetics, indicating monolayer chemisorption. The thermodynamic parameters confirmed that the process was spontaneous and endothermic. The nanocomposite retained over 90% efficiency after four regeneration cycles, demonstrating its stability and reusability. These findings highlight the potential of Z. mauritiana-derived AC/ZnO as a sustainable and cost-effective adsorbent for removing dyes from wastewater.