Design and fast uptake of fluoride using hybrid biopolymers encapsulated magnetic hydroxyapatite beads

Abstract

Hydroxyapatite is the one of the promising defluoridating material. For easy separation and to enhance defluoridation capacity (DC), magnetic iron oxide cum β‐cyclodextrin functionalized hydroxyapatite was prepared and because of its powder form it cannot be used in column studies. To make functionalized magnetic hydroxyapatite in usable bead form it was encapsulated using hybrid biopolymers chitosan and gelatin named as magnetic iron oxide/gelatin‐chitosan/hydroxyapatite/β‐cyclodextrin (MGCHC) composite beads were fabricated and utilized for rapid fluoride removal. The obtained MGCHC hybrid beads exhibited DC of 4985 mgF− kg−1 within 30 min. In co‐anions studies, Cl−, SO42− and NO3− had little influence on fluoride adsorption, whereas HCO3− had major influence on fluoride adsorption. The isotherm and kinetic data of MGCHC beads toward fluoride removal was effectively portrayed with Langmuir and pseudo‐second order model respectively. Defluoridation mechanism of MGCHC beads were mainly followed by electrostatic attraction, ion‐exchange and complexation. This investigation using MGCHC beads affords cost‐effective and eco‐friendly for fluoride removal which gives a practicable way for the fluoride treatment from field water.