Electrochemical strategy for scalable synthesis of MgO nanostructures for efficient removal of Malachite green

Abstract

Present investigation demonstrates a simple and scalable electrochemical approach for synthesis of magnesium oxide (MO) nanoparticles, followed by their adoption on removal study of Malachite Green dye from aqueous solution. Magnesium hydroxide was electrochemically precipitated in a magnesium nitrate bath at a pH of 4.0, with a current density of 200 A m^-². The resulting precipitated product was calcined for 2 hrs. at 500 °C to yield MgO nanoparticles (MO NPs). The MO NPs were characterized by X-ray diffraction (XRD) studies, RAMAN analysis, Fourier Transform Infrared spectroscopy (FTIR) and Field-emission scanning electron microscopy (FESEM) analysis, which confirmed the formation of pure-phase MgO nanoparticles with a flower-petal-like nanostructure. High-resolution transmission electron microscopy (HRTEM) analysis revealed the formation of hierarchical nanostructures with an average particle diameter of ≤ 50 nm. The mesoporous structure of MgO was well ascertained by nitrogen adsorption-desorption isotherms and was supported by pore size distribution analysis. A maximum adsorption capacity of 2000 mg g^-1 was achieved under suitable conditions: 0.004 g of MgO in 20 mL of a 100 mg dm^-3 Malachite green dye solution with a contact time of 45 min. Adsorption isotherm analysis revealed that the data fit both the Langmuir and Freundlich models; however, the Langmuir model exhibited better correlation, suggesting monolayer adsorption. Kinetic studies indicated that the adsorption followed a pseudo-second-order model, with intraparticle diffusion also playing a significant role in the overall adsorption mechanism. This study highlights an efficient and environmentally friendly method for synthesizing MgO-based adsorbents, offering strong potential for scalable industrial applications in water purification and dye removal.