Development of Multivalent Metal-Ion-Fabricated Fumaric Acid-Based Metal–Organic Frameworks for Defluoridation of Water
Antonysamy Jeyaseelan, Mu. Naushad, Natrayasamy Viswanathan
Abstract
Defluoridation plays a vital role in providing drinking water with safe fluoride levels. The present work concentrated on the development of fumaric acid-based metal–organic frameworks (MOFs) using Zr4+, La3+, and Fe3+ metal ions, viz., Zr@Fu, La@Fu, and Fe@Fu MOF composites by the hydrothermal method for defluoridation studies. Fluoride removal from water was investigated and optimized in batch mode. The fabricated Zr@Fu, La@Fu, and Fe@Fu MOF composites have the maximum defluoridation capacities (DCs) of 4920, 4925, and 4845 mgF– kg–1, respectively. The fluoride adsorption studies were conducted by optimizing various affecting parameters like contact time, adsorbent dosage, adsorbate pH, influence of co-ions and temperature. The fabricated Zr@Fu, La@Fu, and Fe@Fu MOF composites were characterized by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), energy-dispersive X-ray analysis (EDAX), X-ray diffractometry (XRD), high-resolution transmission electron microscopy (HR-TEM), selected area electron diffraction (SAED), and atomic force microscopy (AFM) studies. The sorption data were fitted with different isotherm models. The studies of thermodynamic parameters demonstrate the feasibility and endothermic nature of the defluoridation process. The DCs of Zr@Fu, La@Fu, and Fe@Fu MOF composites were compared with other reported adsorbents. The regeneration and reusability studies were proposed to adequately utilize Zr@Fu, La@Fu, and Fe@Fu MOF composites. The field sample taken from a nearby fluoride rife village was also tested with the synthesized Zr@Fu, La@Fu, and Fe@Fu MOF composites, which reduce the fluoride content below the tolerance limit.