Fabricated design of hydrotalcite embedded lanthanum organic frameworks for defluoridation of water

Abstract

AbstractThe surplus fluoride in drinking water leads to diseases namely fluorosis (dental, skeletal, and non‐skeletal). Hence, to overcome these problems, in this study, hydrotalcite (HT) integrated La‐based metal‐organic frameworks (LaMOFs) namely HT‐LaMOFs was fabricated for fluoride removal. The fabricated HT‐LaMOFs material was well characterized by various characterization methods (x‐ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), Energy‐dispersive X‐ray spectroscopy (EDAX), thermogravimetric analysis (TGA), and differential thermal analysis (DTA)) to find the structural properties and stability of HT‐LaMOFs. To find the fluoride adsorption nature, the batch studies were employed towards fluoride adsorption such as reaction time, co‐ions, HT‐LaMOFs dosage, pH, initial fluoride concentration, selectivity, pHzpc, and temperature studies. The contact time studies results reveals that the defluoridation capacity (DC) of HT‐LaMOFs was towards fluoride was found as 4451 mgF− kg−1 at 30 min than HT (1030 mgF− kg−1 at 50 min). The DC had little influences in the presence of HCO3− ion compared to other ions. Fluoride adsorption mechanism of HT‐LaMOFs was initiated to be electrostatic interaction, ion‐exchange and complexation. Fluoride adsorption onto HT‐LaMOFs was well matched and followed with Langmuir model. Thermodynamic investigations exposed that the adsorption of fluoride onto HT‐LaMOFs followed by spontaneous and endothermic nature. Kinetic studies of HT‐LaMOFs on fluoride capture followed with pseudo‐second‐order and intraparticle diffusion models. Defluoridation by HT‐LaMOFs was followed endothermic with spontaneous nature of adsorption system. The regeneration study results of HT‐LaMOFs revealed that the developed HT‐LaMOFs was regenerable up to six cycles. In addition, field study outcomes revealed that the developed HT‐LaMOFs diminished fluoride concentration under the acceptable limit as 1.5 mg/L.