Enhanced fixed-bed column adsorption using a ternary MgO-impregnated eggshell–kaolin composite: Toward an efficient and sustainable fluoride removal technology
Loading...
Date
2026-01-26
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
In this study, a ternary MgO-impregnated eggshell–kaolin (EKM) composite was synthesized and
evaluated for fluoride removal from water under fixed-bed column adsorption. The composite,
prepared by co-precipitation and wet impregnation, was characterized using XRD, FTIR, SEM
EDX, and Brunauer–Emmet–Teller analyses. Results confirmed successful integration of the three
components, yielding a mesoporous structure with a surface area of 158.5 m2 g−1. The composite
exhibited good defluoridation performance under varying operational conditions. Higher bed
depth and lower flow rate enhanced adsorption capacity, achieving up to 6.35 mg g−1 at
10 mg L−1 influent fluoride concentration. Breakthrough data were well described by the
Thomas, Clark, and Yoon–Nelson models (R2 ≥ 0.94) at lower influent concentration, moderate
flow rate, and greater bed depth, while the bed depth service time model confirmed a linear
increase in service time with bed depth. The adsorbent maintained good regeneration ability
across four cycles. Co-existing anions showed interference with the uptake of F−, with inhibitory
effects following the order: PO3−4>SO2−4>NO−3 > Cl−. The study estimated that 11.11 g of
EKM composite yields 2 L of safe water for less than USD1. These results highlight the EKM com
posite as an efficient and sustainable adsorbent for practical defluoridation applications.
Sustainable Development Goals
SDG 6: Clean Water and Sanitation
Keywords
Fixed-bed column adsorption, Breakthrough curve, Composite, Adsorption capacity, Defluoridation