Efficient recovery of highly pure CaF2 from fluorine-containing wastewater using an icy lime solution.
Water Sci Technol
; 90(1): 32-44, 2024 Jul.
Article
in En
| MEDLINE
| ID: mdl-39007305
ABSTRACT
Developing a feasible and low-cost strategy for the recovery of calcium fluoride efficiently from fluoride-containing wastewater is very essential for the recycle of fluoride resources. Herein, a modified lime precipitation method was employed to recover CaF2 from fluorinated wastewater using a special icy lime solution. Intriguingly, the highest F- removal was greater than 95% under the optimal condition, leaving a fluoride concentration from 200 to 8.64 mg/L, while the lime dosage was much lower than that of industry. Importantly, spherical-shaped CaF2 particles with a 93.47% purity and size smaller than 600 nm were recovered, which has a high potential for the production of hydrofluoric acid. Besides, the precipitation was significantly affected by Ca/F molar ratio, stirring time, temperature, and solution pH. Furthermore, the thermodynamics and kinetics were investigated in detail to reveal the crystallization process. As a result, the defluorination reaction followed the pseudo-second order reaction kinetics model. Also, CO2 in the air adversely influenced the CaF2 purity. Based on this facile method, a high lime utilization efficiency was applied to defluorination, which contributed to protecting the environment and saving costs. This study, therefore, provides a feasible approach for the green recovery of fluorine resources and has significance for related research.
Key words
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Oxides
/
Calcium Fluoride
/
Calcium Compounds
/
Wastewater
/
Fluorine
Language:
En
Journal:
Water Sci Technol
Journal subject:
SAUDE AMBIENTAL
/
TOXICOLOGIA
Year:
2024
Type:
Article
Affiliation country:
China