Rotating hydrothermal route to red mud derived uniform hierarchical porous flowerlike boehmite (γ-AlOOH) microspheres: Force analysis on formation mechanism and superior adsorption performances for anionic dyes removal--颗粒学报PARTICUOLOGY

Hui, Q., Hang, Y., Wang, F., Zhang, H., Zhang, L., & Zhu, W. (2024). Rotating hydrothermal route to red mud derived uniform hierarchical porous flowerlike boehmite (γ-AlOOH) microspheres: Force analysis on formation mechanism and superior adsorption performances for anionic dyes removal. Particuology, 94, 229-244. https://doi.org/10.1016/j.partic.2024.08.006

Rotating hydrothermal route to red mud derived uniform hierarchical porous flowerlike boehmite (γ-AlOOH) microspheres: Force analysis on formation mechanism and superior adsorption performances for anionic dyes removal

Qingxue Hui, Yaru Hang, Fei Wang, Heng Zhang^*, Liyun Zhang, Wancheng Zhu^*

Department of Chemical Engineering, Qufu Normal University, Shandong, 273165, China

10.1016/j.partic.2024.08.006

Volume 94, November 2024, Pages 229-244

Received 4 May 2024, Revised 4 July 2024, Accepted 2 August 2024, Available online 18 August 2024, Version of Record 5 September 2024.

E-mail: zhangheng@qfnu.edu.cn; zhuwancheng@tsinghua.org.cn

Highlights

• Rotating hydrothermal route is developed to red mud derived γ-AlOOH microspheres.

• The γ-AlOOH microspheres exhibit distinctly narrow diameter distribution and small average diameter.

• Effect of rotation and rotating force analysis on the formation mechanism are uncovered.

• The γ-AlOOH microspheres exhibit high adsorption capacity for CR (602.4 mg g⁻¹) and MB (1208.7 mg g⁻¹).

• Static DI, dynamic flowing and actual water bodies simulated wastewater are tested.

Abstract

Towards increasingly severe worldwide pollution of industrial solid waste red mud (RM) released from aluminum industry, constitutional valuable element Al has been successfully separated for a novel mild rotating hydrothermal synthesis (150 °C, 12 h, 5 Hz) of the uniform hierarchical porous flowerlike boehmite (γ-AlOOH) microspheres in the presence of appropriate urea, which exhibit distinctly small average diameter (1.52 μm) and narrow particle size distribution (PSD: 1.12–1.97 μm), as well as high specific surface area (129.37 m² g⁻¹). On the one hand, the rotating hydrothermal synthesis promotes the mass and heat transfer, enabling γ-AlOOH microspheres at a lower temperature within a shorter time. On the other hand, moderate rotation provides predominant shear force, rendering the uniform γ-AlOOH microspheres with small average diameter and narrow PSD. The optimal AlOOH–U2M-R5Hz microspheres demonstrate satisfactory adsorption performance for Congo Red (CR) and Methyl Blue (MB), with the maximum adsorption capacities of 602.4 and 1208.7 mg g⁻¹, respectively. Various isotherm models of Langmuir, Freundlich, Temkin and Dubinin-Radushkevich are utilized, adsorption kinetics are analyzed, adsorption mechanism is uncovered based on hydrogen bonding and electrostatic attraction. The increase in the temperature or the presence of coexisting cations facilitates the adsorption of CR, whereas coexisting anions weaken the adsorption of CR on the AlOOH–U2M-R5Hz microspheres. Furthermore, the excellent recycling performances and especially dynamic adsorption (retainment of removal efficiency of approx. 99.0% within 1000 min) as well as authentic water bodies (e.g. tap water and river water) simulated wastewater treatment undoubtedly indicate great practical applications of the AlOOH–U2M-R5Hz microspheres, towards cleaner aluminum production and cost-effective sustainable solution to anionic dye-bearing wastewater.

Graphical abstract

Keywords

Red mud; Valuable metal recovery; Rotating hydrothermal; Boehmite; Dye adsorption

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