Fluoride removal from groundwater using Zirconium Impregnated Anion Exchange Resin

Drinking water containing excess fluoride is a major health concern across the globe. The present study reports the feasibility of zirconium impregnated hybrid anion exchange resin (HAIX-Zr) for treating fluoride contaminated groundwater. The HAIX-Zr resin was prepared by impregnating ZrO₂ nanoparticles on polymeric anion exchanger resin. Fluoride uptake by HAIX-Zr was quite rapid, 60% removal was obtained within 30 min. Kinetics of fluoride uptake by HAIX-Zr resin followed the pseudo-second-order kinetic model and adsorption data fitted best to Freundlich adsorption isotherm model. Maximum fluoride uptake capacity was observed as 12.0 mg/g. The defluoridation capacity of the resin decreases with increase in solution pH. The co-existing anions like chloride, phosphate, bicarbonate, nitrate, and sulphate at 100 mg/L concentration significantly affected fluoride removal and bicarbonate showed the highest interference. Continuous flow packed bed experiments were performed with real groundwater. To maintain a lower pH, weak acid cation exchange resin (INDION-236) was used before HAIX-Zr. It was observed that reducing the pH of the sample water to 4-4.5, increased the number of treated bed volumes fifteen times. Regeneration of fluoride-containing resin was done by passing 3% NaOH and 3% NaCl solution through an exhausted resin bed. The results revealed that HAIX-Zr can effectively remove fluoride from groundwater.