Synergistic adsorption and photocatalytic degradation of organic dyes using bioinspired synthesis of g-C3N4/sugarcane/ZnO composite

The increasing release of synthetic dyes from textile industries poses a significant environmental concern, highlighting the need for effective and eco-friendly remediation approaches. In this work, a ternary composite consisting of sugarcane juice (SJ), zinc oxide and graphitic carbon nitride (g-C 3 N 4 /SJ/ZnO) was prepared through a green synthesis route, with both ZnO and g-C 3 N 4 /SJ synthesized using sugarcane juice as a natural reducing and stabilizing agent. This sustainable approach minimizes the use of toxic reagents while enhancing material stability, adsorption capacity, and photocatalytic activity. The structural and morphological characteristics were examined using FTIR, XRD, UV-DRS, BET, HRTEM, and FESEM-EDS techniques. Although the composite showed a decrease in surface area relative to pristine g-C 3 N 4 , it demonstrated enhanced efficacy due to synergistic interactions between its constituents. The Dubinin–Radushkevich (D–R) isotherm best described the equilibrium data, suggesting a physisorption mechanism. Batch adsorption tests showed a dye uptake capacity (q max ) of up to 1000 mg/g. According to thermodynamic parameters, the adsorption was both endothermic and spontaneous, while kinetic investigations used a pseudo-second-order model. Photocatalytic evaluation revealed 93.31 % dye degradation under visible-light irradiation. In parallel, reusability tests demonstrated stable adsorption performance across three consecutive adsorption–desorption cycles. These findings demonstrate that the g-C 3 N 4 /SJ/ZnO composite offers a promising green-engineered platform for the sustainable treatment of dye-contaminated wastewater. • A g-C 3 N 4 /SJ/ZnO biocomposite was synthesized for dye removal and degradation. • Exhibited a high adsorption capacity of 1000 mg/g for Malachite green dye. • Showed 93.31 % photocatalytic degradation efficiency under visible light. • Adsorption followed the Dubinin-Radushkevich isotherm model. • Demonstrated good selectivity and reusability over three cycles.