Sono-assisted Adsorption of Methyl Violet 2B Using a Magnetic Kaolin/TiO2/γ-Fe2O3 Nano Composite

Abstract

In this study, the efficacy of sono-assisted adsorption for the removal of methyl violet 2B (MV-2B) was investigated. A magnetic adsorbent was synthesized using kaolin and TiO₂, designated as KTF. Various analyses including scanning electron microscopy with energy dispersive spectroscopy (SEM–EDS), Brunauer–Emmett–Teller (BET), Fourier transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), Zeta potential and vibrating sample magnetometer (VSM) were conducted to characterize the structure of KTF. The BET surface area and pore volume of KTF were determined to be 65.279 m²/g and 0.072 cm³/g, respectively. VSM analysis confirmed the superparamagnetic property of KTF. The effect of contact time, initial MV-2B concentration, KTF amount, temperature, ionic strength and initial pH of the solution on the sono-assisted adsorption of MV-2B was investigated. Sono-assisted removal of MV-2B was achieved at a rate of 85.6% under optimal conditions: original pH, KTF amount of 0.2 g/100 mL, initial MV-2B concentration of 20 mg/L, contact time of 15 min, and temperature of 22 °C. Conversely, lower removal efficiencies were observed with conventional adsorption methods employing shaking (37%) and stirring (60.5%). The kinetics of sono-assisted MV-2B removal followed a pseudo-second order model, while the Freundlich isotherm model exhibited a superior fit (R² = 0.985) in describing the equilibrium behavior compared to Langmuir and Temkin models.