Statistically optimized sequential hydrothermal route for FeTiO surface modification: evaluation of hazardous cationic dyes adsorptive removal.

In the present study, the performance of facile hybrid sequential chemical treatments of titanomagnetite concentrate (TC), alkaline leaching, and sodium dodecyl sulfate (SDS) modification has been evaluated for the removal of crystal violet (CV), malachite green (MG), and methylene blue (MB) cationic dyes. The physical and chemical properties of samples were characterized using scanning electron microscopy (SEM), energy dispersive X-ray (EDX), N adsorption-desorption, X-ray diffraction (XRD), X-ray fluorescence spectroscopy (XRF), and Fourier transform infrared spectroscopy (FTIR) analyses. Moreover, dye removal in the batch system was investigated by evaluating adsorbent dosage, contact time, initial dye concentration, pH of the solution, temperature, electrolyte concentration, adsorption isotherm, kinetic, and thermodynamic. The results showed that the maximum adsorption capacity was obtained at SDS concentration of 6 mM, NaOH concentration of 9 M, the temperature of 160 °C, solid/liquid ratio of 4 g/100 mL, and the process duration of 24 h. In the alkaline leaching process, forming the NaTiO phase with sharp and high energy points can be improved the adsorption properties. Accordingly, the adsorption capacity and removal efficiency attained 19.84, 18.64, and 19.66 mg/g and 99.21, 93.24, and 98.31% for CV, MG, and MB, respectively. Furthermore, the dye removal followed pseudo-second-order (R = 0.9990) and Freundlich (R = 0.9970) models. The evaluation of thermodynamic parameters indicated the endothermic (∆H° = 110.91 J/mol) and spontaneous nature (ΔG˚ < 0) of the adsorption process. This study concluded that the modified TC had a potential ability for application in textile wastewater treatment.