High performance hydroxyiron modified montmorillonite nanoclay adsorbent for arsenite removal

In the present study, hydroxyiron-modified montmorillonite (HyFe-MMT) nanoclay was prepared using a simple wet chemical synthesis method. Arsenite (As (III)) removal using raw montmorillonite and HyFe-MMT was compared and evaluated by adsorption experiments conducted under various conditions (adsorbent dosage, iron loading, contact time, pH, and initial As (III) concentration). The nanoclays were characterized using X-ray diffraction (XRD), X-ray fluorescence (XRF), Fourier transform infrared spectrometry (FTIR), BET surface area analysis, thermogravimetric analysis, scanning electron (SEM) microscopy, and transmission electron microscopy (TEM). Fast adsorption kinetics were observed in which more than 55% of As (III) was removed using HyFe-MMT within the first 30 s of the adsorption process. The kinetics were most accurately modeled using the pseudo-second-order equation (R² = 1). Optimum As (III) adsorption was obtained between a pH of 6 to 7. The Freundlich model properly described the adsorption process (R² > 0.99). It was determined that the adsorption capacity of raw MMT was increased to more than five times after iron modification. The HyFe-MMT adsorbent presented could be used for arsenic contaminated groundwater, drinking water, or wastewater.