Magnesium Molybdate: An Efficient Nanosorbent for Methylene Blue Cationic Dye Removal from Aqueous Solutions

The removal of methylene blue (MB) cationic dye from aqueous solutions was investigated by applying magnesium molybdate (β-MgMoO₄) as a nanosorbent. The β-MgMoO₄ was synthesized through a simple, rapid, and efficient method. The MB dye removal process was optimized by evaluating various parameters such as temperature, contact time, nanosorbent dosage, pH, and initial cationic dye concentration. The optimal conditions for MB removal were found to be pH 3, with a 99% removal efficiency achieved in just 10 min of contact time, when using an MB cationic dye concentration of 160 ppm. Magnesium molybdate (β-MgMoO₄) showed a maximum adsorption capacity of 356 mg/g, according to Langmuir model-based calculations. The MB dye removal process occurred spontaneously while being favorable and endothermic. The kinetic investigation showed that the pseudo-second-order model accurately represented the reaction kinetics. The thermal regeneration test results indicated that the removal efficiency remained stable even after three consecutive rounds of reuse. A Fourier Transform Infrared (FTIR) spectroscopic analysis confirmed the adsorption and desorption of MB on β-MgMoO₄ and its regeneration. Overall, these results indicate that a β-MgMoO₄ nanosorbent is a favorable and robust adsorbent for the removal of MB cationic dye from wastewater at its maximum capacity.