Facile Synthesis of MnCO3/ZrO2/MgCO3 Nanocomposite for High-Efficiency Malachite Green Dye Removal

Malachite green dye poses significant environmental and health risks due to its high toxicity, persistence, and bioaccumulative nature, causing severe impacts on aquatic ecosystems and posing mutagenic, carcinogenic, hepatotoxic, and neurotoxic risks to humans. This study addresses these concerns by synthesizing a novel MnCO3@ZrO2@MgCO3 nanocomposite through a precipitation method to remove malachite green from contaminated water. The X-ray diffraction (XRD) analysis confirmed the crystallinity of each composite component, with a mean crystallite size of 85.89 nm. The Brunauer-Emmett-Teller (BET) analysis revealed a surface area of 28.35 m2/g, a total pore volume of 0.0289 cm3/g, and an average pore size of 1.98 nm. The nanocomposite achieved a maximum adsorption capacity of 232.58 mg/g for malachite green dye at an optimum pH of 10, an adsorption equilibrium time of 70 min, and a temperature of 298 K. Regeneration studies demonstrated that the nanocomposite retained over 90% removal efficiency across five adsorption-desorption cycles, showcasing its reusability. Thermodynamic evaluation demonstrated that the adsorption process was exothermic (Delta H degrees = - 36.83 kJ/mol), spontaneous (negative Delta G degrees values), and predominantly physical, adhering to the pseudo-second-order kinetic model and Langmuir isotherm.