Mechanism and performance of Fluoride's removal using hydrochar modified by different loadings of aluminum source

Xu Fuqiang; Gong Miao; Liu Piao; Xu Qiao; Su Ying; Fan Yujie; Guo Shuai

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Mechanism and performance of Fluoride's removal using hydrochar modified by different loadings of aluminum source

Updated：2026-08-24

- Mechanism and performance of Fluoride's removal using hydrochar modified by different loadings of aluminum source
- Chinese Journal of Chemical Engineering Vol. 94, Issue 6, Pages: 44-59(2026)
- Affiliations：
  
  School of Civil Engineering, Hefei University of Technology, Hefei 230009, China
  Anhui Provincial Engineering Laboratory for Rural Water Environment and Resources, Hefei 230009, China
  College of Civil Engineering, Yancheng Institute of Technology, Yancheng 224051, China
  School of Civil Engineering, Nanyang Institute of Technology, Nanyang 473004, China
- Author bio：
  
  Corresponding authors. E-mail addresses: miaogong@hfut.edu.cn(M. Gong)
  guoshuai@hfut.edu.cn(S. Guo)
- Funds：
- DOI：
  CLC：
- Received：28 September 2025，
  
  Revised：2025-12-16，
  
  Accepted：24 December 2025，
  
  Online First：14 March 2026，
  
  Published：2026-06
- Accepted：
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Xu Fuqiang, Gong Miao, Liu Piao, et al. Mechanism and performance of Fluoride's removal using hydrochar modified by different loadings of aluminum source[J]. Chinese Journal of Chemical Engineering, 2026, 94(6): 44-59.
DOI：

Xu Fuqiang, Gong Miao, Liu Piao, et al. Mechanism and performance of Fluoride's removal using hydrochar modified by different loadings of aluminum source[J]. Chinese Journal of Chemical Engineering, 2026, 94(6): 44-59. DOI：

摘要

Abstract

The present study prepared aluminum-functionalized hydrochars through a single-step hydrothermal carbonization reaction of sewage sludge using various Al precursors (namely AlCl

(SO

)

Al(NO

)

Al(OH)

and Al

). We found that ligand properties and hydrolysis pathways determine the formation of Al(OH)

/AlOOH and low-reactivity Al

regions

thereby regulating the density and accessibility of surface Al―OH sites and thus affecting fluoride binding. X-ray photoelectron spectroscopy (XPS) analysis revealed that Cl

by forming [AlCl(H

]

species through coordination

retarded the hydrolysis kinetics and promoted the synergistic formation of Al(OH)

(39.04%) and AlOOH (47.52%).

Conversely speaking

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induced the oriented growth of layered hydroxides through a templating effect

while the weak coordination capability of

https://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=116192057&type=

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led to dehydroxylation and the predominant formation of inert Al

(20.92%) with low―OH functionality. Under optimized conditions (30% AlCl

)

organic decomposition increased BET surface area to 111.54 m

·g

- 1

(44% over unmodified hydrochar)

yielding Langmuir capacity of 24.10 mg·g

- 1

(10-fold enhancement)

via

pseudo-second-order kinetics and Freundlich isotherms. Fluoride sequestration primarily occurred through hydroxyl-fluoride ligand exchange

which was augmented by electrostatic interactions and mesoporous confinement. The hydrochar retained 70% capacity over five cycles

with anion interference followed the order:

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＞

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＞

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＞Cl

. These findings highlight the potential of aluminum-modified hydrochar for efficient removal of fluoride from aqueous solutions and resource valorization of sewage sludge.

关键词

Keywords

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