Mesoporous Al₂O₃ derived from blast furnace slag as a cost-effective adsorbent for U(VI) removal from aqueous solutions

ABSTRACT

This work provides an environmental approach to utilise Blast furnace slag (BFS) waste for the processing of aluminium oxide (Al₂O₃-BFS) as an efficient adsorbent for uranium removal from wastewater. The composition of BFS is less variable and this makes it a low cost and abundant raw material for preparing a solid base Al₂O₃-BFS. The silica material was initially removed and then the aluminium content was separated by precipitation with sodium hydroxide depending on pH control (pH 5.5). The raw BFS and Al₂O₃-BFS were characterised via various methods, such as; XRD, Zeta potential, N₂ adsorption-desorption isotherm, DLS, and FT-IR. BFS exhibited the typical type III isotherm with an H3-type hysteresis loop. The curve of Al₂O₃-BFS exhibited the typical IV isotherms with a H2-type hysteresis loop. The BET surface and average pore sizes of the Al₂O₃-BFS are 137.7 m2 g-1 and 3.9 nm, respectively. Experiments and discussions were performed in terms of balance, isothermal, kinetic, and applicability. The finding provides proof of the ability of synthesised Al₂O₃-BFS to remove U(VI) ions from wastewater as an efficient adsorbent with a maximum sorption capacity value of 62 mg/g. The pseudo second, Langmuir and Dubinin-Radushkevich models were found suitable to explain the rate kinetics and isotherm of uranium removal. Uranium sorption on Al₂O₃-BFS may occur via inner-sphere complex and ion-exchange between uranium ions and HO-Al₂O₃-BFS groups. The higher elution efficiency of Al₂O₃-BFS indicates a promising adsorbent in the technology of U(VI) removal.

KEYWORDS:

• Al₂O₃
• blast furnace slag
• removal
• uranium

Acknowledgments

The authors acknowledge Taif University Researchers Supporting Project number (TURSP-2020/05), Taif University, Taif, Saudi Arabia.

Disclosure statement

No potential conflict of interest was reported by the authors.