Facile design of metal ion fabricated benzene-1,3,5-tricarboxylic acid based metal organic frameworks for defluoridation of water

Abstract

The leaching of fluoride in potable water leads to fluorosis. To prevail over this trouble, tunable porous metal organic frameworks (MOFs) were prepared by solvothermal method and utilized for fluoride removal. Herein, polyvalent metal ions namely Zr4+, Fe3+ and Al3+ fabricated benzene-1,3,5-tricarboxylic acid (BTC) based MOFs namely Zr-BTC, Fe-BTC, and Al-BTC MOFs exhibits higher defluoridation capacities (DCs) of 4998, 4940, and 4920 mgF- kg-1 respectively. The developed metal based BTC (M-BTC) MOFs were investigated by XRD, TEM, SEM, FTIR, XPS and EDAX investigation. The influencing factors of adsorption viz., solution pH, M-BTC MOFs dosage, shaking time, preliminary fluoride concentration, temperature, and challenger anions were optimized under batch scale. The fluoride adsorption ability of M-BTC MOFs was slightly affected by adsorbate pH medium and bicarbonate ion in water. In addition, the experimental data was fitted with various adsorption kinetic and isotherm models. The thermodynamic investigation shows the feasible, spontaneous and endothermic nature of fluoride adsorption. The plausible fluoride adsorption mechanism of M-BTC MOFs was majorly ruled by electrostatic attraction and complexation. Furthermore, synthesized M-BTC MOFs can be reused upto eight cycles. The field trial indicates M-BTC MOFs diminish fluoride concentration below the acceptance limit in field water which helps in supply of water with secure fluoride levels.