Organometallic absorbent for mitigating fluoride from water: an environment-friendly approach

Fluoride-related health hazards are a serious environmental problem across the globe. Unavailability of an effective therapeutic agent to cure fluorosis creates an exigency to adopt preventive measures to curb excess fluoride intake. Herein, we report a zirconium-based organometallic adsorbent (ZrVAc) for mitigating fluoride from water. The crosslinked, three dimensional and porous architecture of ZrVAc, composed of zirconyl methacrylate (ZrDMA) and vinyl acetate (VAc) have high porosity and excellent mechanical stability. The experimental factors such as effects of solution pH, coexisting anions, temperature, pHpzc, isotherm models and surface chemistry were investigated to verify the adsorption properties of ZrVAc. The equilibrium data were fitted well with Freundlich and Langmuir adsorption isotherms. The highest fluoride adsorption capacity (qm) was found to be 138 mg/g (at pH 7.0±0.2, initial F− concentration 100 mg/L, adsorbent dose 0.5 g/L for 6 h). The thermodynamic constants ΔG, ΔH, and ΔS were calculated as 45.158 KJ mol−1 (at 303 K), −37.64 KJ mol−1, and −0.161 KJ mol−1. ZrVAc showed efficient adsorption in pH range of pH 6.0-8.0 which is preferable for field water application. Toxicity characteristics leaching procedure (TCLP) results suggested the ZrVAc was inert; does not leach out any contaminants (Zr, F−) and delivers safe and potable treated water.