Effective adsorption of methylene blue using natural Saudi zeolite as a low-cost sustainable adsorbent

The increasing threat of dye pollution in water resources underscores the urgent need for sustainable and cost-effective treatment solutions However, a gap remains in identifying efficient and reusable natural materials for dye removal. This study evaluates the potential of natural zeolite as an effective and reusable adsorbent for removing methylene blue dye from aqueous solutions. Natural zeolite was characterized using SEM, FTIR, XRD, and TGA techniques, and its adsorption performance was systematically tested under various conditions, including pH, adsorbent dosage, contact time, temperature, and initial dye concentration. The results revealed a maximum dye removal efficiency of 98.9% under optimized conditions (pH = 7, adsorbent dosage = 0.01 g/L, contact time = 60 min, temperature = 25 °C) and a monolayer adsorption capacity of 24.71 mg/g. The adsorption process conformed to the Langmuir isotherm and followed pseudo-second-order kinetics, indicating monolayer coverage and chemisorption mechanisms. Thermodynamic analysis confirmed the adsorption process was spontaneous and exothermic. Recycling experiments demonstrated the zeolite's strong reusability, highlighting its potential as an economically viable and environmentally friendly method for wastewater treatment applications. Further research should explore real wastewater applications and scale-up potential to support practical implementation.