Zirconium oxide intercalated sodium montmorillonite scaffold as an effective adsorbent for the elimination of phosphate and hexavalent chromium ions

Abstract

The presence of oxyanions such as hexavalent chromium (Cr(VI)) and phosphate in water resources posing significant threat to both environment and human beings. Therefore, the present investigation focused on the elimination of phosphate and Cr(VI) anions from water by employing zirconium oxide intercalated sodium montmorillonite (ZrO2-NaMMT@700) composite as an adsorbent. The prepared ZrO2-NaMMT@700 composite was characterized using Fourier transform infrared spectroscopy (FTIR), powder X-ray diffraction (PXRD), scanning electron microscopy with energy dispersive X-ray analysis (SEM-EDX), X-ray photoelectron spectroscopy (XPS) and Brunauer–Emmett–Teller (BET) surface area analyzer. The surface characterization results confirmed the successful intercalation of ZrO2 nanoparticles into NaMMT. The ZrO2-NaMMT@700 composite showed better and rapid removal for phosphate and Cr(VI) anions with the maximum adsorption capacity of 64.57 and 52.46 mg/g, respectively. The adsorption studies suggested that removal of phosphate and Cr(VI) was mainly driven by the electrostatic attraction and electrostatic attraction coupled reduction, respectively. Besides, the obtained phosphate and Cr(VI) adsorption data were well described by the Langmuir isotherm and pseudo-second-order kinetic models. Furthermore, the exhausted ZrO2-NaMMT@700 composite could be easily regenerated and reused in subsequent adsorption experiments. Overall, due to the easy synthesis, excellent adsorption capacity, and regeneration ability, the prepared ZrO2-NaMMT@700 composite could be served as a potential candidate for the removal of phosphate and Cr(VI) anions.