Amorphization of natural ilmenite for production of a potential porous adsorbent towards crystal violet dye removal from aqueous environment

Abstract

In this work, amorphization of ilmenite mineral was obtained by solid NaOH alkaline fusion at 550 oC. The material was tested as an adsorbent towards crystal violet (CV) removal from an aqueous matrix. Several techniques, such as X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), and N2 adsorption/desorption isotherms (BET) were used to characterize the material, and revealed an amorphous structure with superior surface area (88.84 m² g-1) compared to raw sample (5.90 m² g-1). These intrinsic characteristics resulted in a satisfactory adsorption capacity, reaching 133 mg g-1 at a temperature of 328 K. Kinetic studies on the adsorption process indicated that the equilibrium condition was reached within 50 min, being well represented by the Avrami model. The thermodynamic study revealed that the CV adsorption onto ilmenite is spontaneous, endothermic, and favorable. The amorphized material maintains the same adsorptive performance after three reuse cycles. Therefore, the amorphization route proposed in this work was satisfactory for producing a porous adsorbent from the ilmenite mineral, with potential use for wastewater treatment.