Green Synthesis of Iron Nano-Impregnated Adsorbent for Fast Removal of Fluoride from Water

•Green synthesis of iron nanocomposite material- eco-friendly method•Fast and selective fluoride removal from water•Economic removal due to low contact time and dose•Eco-friendly method due to capability to work at natural pHs of water bodies

Iron nano-impregnated adsorbent was synthesized, characterized and applied for fluoride subtraction from the water. Maximum fluoride removal (90%) was at 4.0 mg/L concentration, 25.0 min. contact time, 7.0 pH, 2.5 g/L dose and 293 K temperature. Iron nanocomposite adsorbent was selective for fluoride removal. The experimental data obeyed Langmuir, Freundlich and Temkin models. The values ΔG° were − 1.89, − 0.86 and − 0.74 kJ/mol at 293, 298 and 303 K temperatures. ΔH° value was − 7.61 kJ/mol; indicating exothermic adsorption. ΔS° value was − 2.30 x 10− 2 kJ/mol K; a signal of entropy decrease during adsorption. The adsorption process was in the order of 293 > 298 > 303 K. Kinetic modeling confirmed pseudo-first-order and liquid film diffusion mechanisms. The mechanism of adsorption is also determined.