Gamma radiation-induced synthesis of organoclays based polyaniline and ilmenite clay minerals for cesium ions removal from aqueous solutions

Abstract

In this study, new eco-friendly organoclays sorbents-based bentonite clay (bentonite/polyaniline OC1 and bentonite/polyaniline/ilmenite OC2) were prepared by gamma radiation. Characterization of the prepared materials was done using Fourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM), X-ray diffraction (XRD), and energy dispersive X-ray analysis (EDX). The results show that polyaniline molecules and ilmenite penetrate the bentonite host material at montmorillonite sites. The synthesized sorbents were tested to remove cesium ions from the aqueous solutions. The parameters affecting the adsorption of cesium were also investigated, such as contact time, pH, the initial metal ion concentration, and the adsorbent dosage. The regeneration tests reflect the long-term stability of the prepared sorbent up to 5 cycles. The optimum conditions for adsorption of cesium ions using the mentioned sorbents were found at a contact time of 120 min and pH of 6–7 and 0.05 g dose weight. The maximum adsorption capacity of Cs+ reached about 24.7 mg/g and 34.4 mg/g for the prepared bentonite/polyaniline and bentonite/polyaniline/ilmenite at 25°C, respectively. The desorption experiment indicates that 0.1 M NaOH and 0.1 M HCl were chosen as the best eluents for loaded cesium on OC1 and OC2, with desorption rates of 45% and 15%, respectively. The thermodynamic investigation suggested the exothermic and spontaneous nature of the adsorption process. The removal efficiency of Cs+ from simulated aqueous mixture was found to fellow this order Cs+ > Co++ > Na+ > K+ ≫ Cr+6 this behavior reflects the selectivity of the synthesized adsorbents based bentonite towards Cs ions. Furthermore, this unique, cost-effective, and environmentally bentonite/polyaniline/ilmenite organoclay has good merits and can be utilized to separate pollutants for wastewater treatment applications.