Nano-hydroxyapatite coated activated carbon impregnated alginate: A new hybrid sorbent for uranium removal from potable water

In this study, a new sorbent was synthesized by coating nano-hydroxyapatite on activated carbon (HAP-AC) and immobilized into the alginate matrix. The HAP-AC composite was prepared by coating HAP on activated carbon powder (AC) by the in situ method. The HAP-AC impregnated in alginate beads (HAP-AC-Alginate) was found to be highly efficient ( > 92%) for the removal of uranium from the portable water. Various physicochemical conditions like the uptake of U in percentage with a varying initial concentration of uranium, pH 5-7, contact time (7 h) were optimized using the batch method. The synthesized HAP-AC composite and the HAP-AC-Alginate beads were characterized using SEM-EDS and XRD. Kinetic models and adsorption isotherm equations (Langmuir & Freundlich) were used to fit the experimental data for describing the sorption process. The results show that the sorption follows the Langmuir isotherm model and the pseudo-second-order kinetic process. The maximum sorption capacity of the HAP-AC-Alginate hydrogel bead is 18.66 mg g(-1). The applicability of the beads was examined in the presence of the interfering ions Na+, Ca+2 , and Fe+3.