Sustainable nanocellulose-supported ZIF-8/ZnO/activated carbon heterostructures enhance charge separation for efficient photocatalytic dye remediation

Abstract

Abstract The presence of synthetic dyes such as Methylene Blue (MB) and Methyl Orange (MO) in water sources presents a significant environmental issue, attributed to their stability and toxic properties. This study presents the fabrication and evaluation of a multifunctional ZIF-8/ZnO/Activated Carbon/Nanocellulose composite for its photocatalytic efficiency under optimized conditions. The characterization results confirmed the development of a hierarchical porous structure characterized by an increased surface area, enhanced light absorption, and improved charge separation. Photocatalytic degradation tests demonstrated that the composite attained maximum efficiencies of 91.8% for MB and 87.4% for MO under optimal conditions of pH 7, a catalyst dose of 0.3 g/L, a temperature of 30 °C, and 60 min of UV irradiation. The adsorption behavior conformed to the Langmuir model, exhibiting high monolayer capacities of qmax (53.0 mg/g for MB and 50.1 mg/g for MO), which indicates a strong affinity between the composite and the dye molecules. Kinetic analyses indicated a pseudo-second-order mechanism, and thermodynamic findings validated the spontaneous and exothermic characteristics of the process. The composite exhibited strong stability across five cycles, demonstrating negligible efficiency loss. The interaction between ZIF-8, ZnO, activated carbon, and nanocellulose markedly improved adsorption, charge transfer, and radical generation, rendering this composite an efficient material for sustainable wastewater treatment .