Faujasite zeolite synthesized by alkali fusion-hydrothermal method from molybdenum tailings for methylene blue adsorption

This study successfully prepared a faujasite-type zeolite from molybdenum tailings through alkali fusion and subsequent hydrothermal synthesis. Adsorption experiments on methylene blue (MB) by synthesized zeolite material. The synthesized zeolite exhibited a specific surface area of 477.556 m² g⁻¹, a total pore volume of 0.2793 cm³ g⁻¹, and an average pore diameter of 2.34 nm. Surface characterization revealed numerous active sites, such as hydroxyl groups. These features were confirmed through XRD, FTIR, SEM, and XPS. Under optimized conditions (solid–liquid ratio of 2 g L⁻¹, pH = 6, initial MB concentration of 100 mg L⁻¹ at 25 °C), the synthesized zeolite achieved a removal efficiency of 92.23 % for MB, with adsorption capacity reaching 45.23 mg g⁻¹. A pseudo-second-order rate equation (R² > 0.998) defined the adsorption process, suggesting chemisorption is the rate-limiting phase. The Freundlich isotherm model suited equilibrium data better (R² > 0.971), indicating that multilayer coverage on a heterogeneous surface drove adsorption. Further mechanistic insights suggested that MB uptake was driven by a combination of surface adsorption, electrostatic attraction and hydrogen bonding. These findings provide both theoretical guidance and technological support for the valorization of molybdenum tailings and their application in the development of low-cost wastewater treatment strategies.