A novel tri-metal adsorbent used for defluoridation technique from groundwater: performance and mechanism

In this research article, a novel adsorbent (Zn-Fe-Al) was synthesized successfully by a simple chemical route where three oxides combined to enhance affinity towards fluoride. The physicochemical properties of the adsorbent were used to characterize and assess its effectiveness in defluoridation with both synthetic and groundwater. The TEM results demonstrated the overlapping of metals, and EDX shows the metals present in the adsorbent. The maximum defluoridation efficiency (97%) of Zn-Fe-Al was obtained at an optimized initial pH 7 and adsorbent dose 0.08 g L−1. The fluoride adsorption on Zn-Fe-Al followed the D-R isotherm and intraparticle diffusion. The maximum adsorption capacity of Zn-Fe-Al was found to be 187 mg g−1. The adsorption of fluoride on Zn-Fe-Al was found to be endothermic and spontaneous. The Zn-Fe-Al adsorbent exhibited satisfactory defluoridation performance on real groundwater. The co-existing ions were also investigated. The adsorption mechanisms for fluoride were electrostatic interaction and ion exchange. These results demonstrated that Zn-Fe-Al adsorbent was considered high potential for effective defluoridation of groundwater.