Highly Porous Iron-Zirconium-Zinc Ternary Metal Oxide Scaffold: Facile Synthesis and Efficient Removal of Malachite Green from Water

Designing water-stable and sustainable adsorbents for wastewater management has gained significant importance nowadays. This paper reports coprecipitation-induced rapid synthesis of a highly porous ternary metal oxide (TMO), its characterization, and efficient removal of malachite green (MG) from simulated water by a batch method. The material was characterized by the Brunauer-Emmett-Teller (BET) surface area, scanning electron microscopy (SEM), powder X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, point of zero charge (pH(zpc)), and chemical analysis. With a high surface area of 185.04 m(2)/g, TMO offers an excellent adsorption capacity of 133 mg/g under optimized conditions. pH dependent adsorption was seen, and maximum adsorption was attained at the neutral condition, i.e., pH 7. Intraparticle diffusion (R-2 = 0.998) and a combined Langmuir and Freundlich isotherm model (R-2 = 0.987-0.998) best describe the adsorption pathway, suggesting that the process undergoes diffusive mass transfer and multilayer adsorption. The adsorption mechanism is proposed to be a combination of electrostatic interaction and hydrogen bonding. Thermodynamic parameters suggest a spontaneous (Delta G, -3.335 kJ/mol), feasible, and exothermic (Delta H, -8.436 kJ/mol) process. The low activation energy (3.459 kJ/mol) suggests a physisorption process. The material can be regenerated up to 83% by 0.1 M hydrochloric acid and reused for up to four cycles without significant loss of activity.