Development of a novel and eco-friendly Alginate@ZIF-8/Moringa Oleifera nano-biocomposite (Alg@ZIF-8/MO-NBC) for environmental remediation through efficient methylene blue removal from aqueous solutions

The persistent presence of synthetic dyes such as methylene blue (MB) in industrial wastewater poses serious environmental and health hazards due to their toxicity, stability, and resistance to conventional treatment methods. In this study, we report the development of a novel and eco-friendly Alginate@ZIF-8/Moringa Oleifera nano-biocomposite (Alg@ZIF-8/MO-NBC) for the effective adsorption of MB from aqueous solutions. The composite was fabricated by incorporating Zeolitic Imidazolate Framework-8 (ZIF-8) into a matrix of sodium alginate and carbonized Moringa Oleifera seed powder. Comprehensive characterization using SEM confirmed the composite's hierarchical porous structure, while FTIR revealed functional group interactions among the components. XRD analysis validated the crystalline structure of ZIF-8, and TGA demonstrated enhanced thermal stability. BET analysis showed a high specific surface area of 452.8 m²/g and mesoporous nature. Adsorption studies revealed a maximum MB uptake of 297.84 mg/g with a removal efficiency exceeding 98.54 %. The adsorption kinetics were best described by the pseudo-second-order (PSO) model, with high correlation coefficients for both linear (R² = 0.9994) and nonlinear (R² = 0.9996) fittings at initial MB concentration of 100 mg/L. Similarly, equilibrium data conformed well to the Langmuir isotherm model, with R² values of 0.999 (linear) and 0.998 (nonlinear), indicating monolayer adsorption. Thermodynamic analysis confirmed that the process is spontaneous and endothermic. Notably, the composite exhibited excellent reusability, maintaining over 90 % efficiency after 5 cycles. These results highlight the Alg@ZIF-8/MO-NBC composite as a promising, sustainable material for advanced wastewater treatment applications.