Synthesis, Characterization and Application of ZrCl4-Graphene Composite Supported on Activated Carbon for Efficient Removal of Fluoride to Obtain Drinking Water

The aim of this study is to evaluate the fluoride removal from contaminated water using a new adsorbent material of high efficiency to obtain drinking water. The ZrCl4-graphene supported on vegetal activated carbon composite (G-ZrCl4/VAC) was synthesized and characterized using transmission and scanning electron microscopy, N2 physisorption, energy dispersive X-ray spectrometry, Fourier transform-infrared spectroscopy, X-ray diffraction, and Raman spectroscopy. Furthermore, the point of zero charge was determined. The G-ZrCl4/VAC was evaluated for fluoride adsorptive removal from water under several operating conditions in batch system. The results indicated that fluoride adsorption by G-ZrCl4/VAC is favored at low pH values with the maximum adsorption at pH 2, corresponding to 97.22% removal. Among the conditions of temperature and agitation evaluated, the best results were achieved at 30 °C and 130 rpm, with removal percentages equal to 47.78 and 48.48%, respectively. The equilibrium of the system was achieved in 5 h of operation. The pseudo-first order kinetic model was the one that best described the kinetic data, while the equilibrium data were best described by the Langmuir isotherm with maximum adsorption capacity equal to 3.89 mg g−1. Therefore, the results obtained show that the material synthesized has a great capacity for adsorption and demonstrate the viability of use of G-ZrCl4/VAC in the removal of fluoride to obtain drinking water.