Abstract
The 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, pH(zpc), 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.