ABSTRACT
In this work, mesoporous spherical γ-AlOOH and γ-Al2O3 particles were rapidly prepared by spray pyrolysis (SP) at different temperatures (400°C–700°C) without the use of template materials. A sol-gel-derived colloidal solution of boehmite was ultrasonicated to generate fine droplets, which were continuously and rapidly transferred into a quartz reactor heated at a specific temperature by a constant flow of N2 gas. Under ultrasonication-assisted spray conditions, a phase change from boehmite to γ-alumina occurred at a temperature of 500°C, leading to a decrease in the surface area and surface hydroxyl group density of the products. At 400°C, the produced γ-AlOOH microspheres exhibited the highest surface area values of ca. ~ 510 m2/g and a surface hydroxyl group density of ca. ~ 2.92 mmol/g, surpassing those of commercial boehmite. The Cr (VI) removal experiments revealed that γ-AlOOH and γ-Al2O3 microspheres have good adsorption performance towards Cr6+. The optimal γ-AlOOH spheres exhibited the highest Cr(VI) adsorption capacity of ca.~ 44.5 mg/g (~74%) at 27 °C and pH = 5.5. After five adsorption-desorption cycles, the synthesised boehmite powder remained a Cr6+ adsorbing capacity of ~ 78%. Notably, the fabricated SP-γ-AlOOH was capable of simultaneously removing Cr6+ and textile dye from the solution. This study provides a facile, rapid, and scalable approach for producing boehmite powder with improved properties for Cr (VI) adsorption.
Acknowledgments
This research is funded by Vietnam National Foundation for Science and Technology Development (NAFOSTED) under grant number 104.05-2020.32. This work is also supported by the Industrial University of Ho Chi Minh City, Vietnam. The authors are thankful to Professor Jinsoo Kim (Chemical Engineering Department, Kyung Hee University, Republic of Korea) for analyzing the samples.
Disclosure statement
No potential conflict of interest was reported by the author.
Supplementary material
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