ORIGINAL RESEARCH
Effect of Freeze-Thaw Cyclic Aging on the
Adsorption Performance of Sheep Manure Biochar
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1
School of Materials and Environmental Engineering, Chengdu Technological University, Chengdu 611730, China
2
Sichuan Environmental Protection Key Laboratory of Persistent Pollutant Wastewater Treatment, Chengdu 610066,
China
3
Engineering & Technology Center of Groundwater Pollution Control for Environmental Protection in Sichuan, Chengdu
610081, China
Submission date: 2025-03-04
Final revision date: 2025-03-20
Acceptance date: 2025-04-06
Online publication date: 2025-06-04
Corresponding author
Yixin Lu
School of Materials and Environmental Engineering, Chengdu Technological University, Chengdu 611730, China
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ABSTRACT
Biochar, SMB, was prepared from waste sheep manure and aged under simulated freeze-thaw cyclic
conditions, and the effects of freeze-thaw cyclic aging on the performance and behavioral features of
SMB when adsorbing methylene blue (MB) dye in water and its influence mechanism were investigated.
The results showed that 7~42 cycles of freeze-thaw aging could effectively improve the pore structure of
SMB and enhance its adsorption performance. After 14 freeze-thaw cycles, SMB could remove 95.7%
of MB under the optimal operating conditions, and the adsorption amount of MB reached 143.5 mg/g,
which was 14% higher than that of unaged SMB. When the freeze-thaw cycles reached 49, the pore
structure of SMB was damaged, and its adsorption performance deteriorated, and the adsorption amount
of MB was 18.8% lower than that before aging. The adsorption behaviors of SMB on MB both before and
after freeze-thaw cyclic aging were chemically dominated, multilayered, entropy-driven, spontaneous,
and heat-absorbing. Freeze-thaw cyclic aging increased the chemical dominance and spontaneity of
adsorption in the shorter term, while decreasing them in the longer term. The adsorption mechanisms
all involved electrostatic attraction, pore filling, hydrogen bonding, and π-π bonding interaction, with
pore filling being enhanced after shorter-term freeze-thaw cyclic aging. The findings provide broader
theoretical support for the application and promotion of SMB in actual pollution management.