The problem of excessive fluoride may exist in many industries, especially in those industries that use fluorine-containing chemicals or may introduce fluoride during the production process. Fluorine-containing chemicals such as hydrofluoric acid are often used in the production process of photovoltaic, new energy batteries, pharmaceutical industry, metal cleaning processing, semiconductor, glass etching processing and other industries, which will cause the fluoride ion concentration of direct wastewater and wastewater generated during cleaning to exceed the standard and fail to meet the discharge standard. If the wastewater is discharged without proper treatment, the fluoride level in the environment may exceed the safety standard, posing a potential risk to the ecosystem and human health. Therefore, these industries need to take corresponding governance measures to ensure that the fluoride concentration in the discharge meets the relevant national or local standards.
Defluoridation agents are chemicals used to treat excess fluoride ions in industrial wastewater or wastewater from other sources. Their main function is to reduce the concentration of fluoride ions during wastewater treatment so that it meets the national or local emission standards and prevents environmental pollution due to excessive fluoride. The working principle of defluoridation agents mainly relies on chemical or physical methods to remove fluoride ions from water. There are two main working principles of common defluoridation agents.
1. The principle of chemical precipitation is: by adding certain chemicals, such as calcium salts or aluminum salts, to the wastewater, these chemicals can react chemically with fluoride ions in the water to form insoluble fluoride precipitates (such as CaF₂ or AlF₆³⁻). The formed precipitates can be removed by subsequent flocculation and coagulation precipitation steps, such as adding flocculants or coagulants (such as polyaluminum chloride PAC, polyacrylamide PAM, etc.) to the wastewater. These agents can increase the volume and weight of suspended particles in the water, promote their sedimentation, and can also help capture fluoride ions.
2. The principle of adsorption is: using adsorbents with high surface area and special functional groups, such as modified clay, activated carbon, zeolite, aluminum-based adsorbents, rare earths, etc., these adsorbents have strong affinity on the surface and can effectively adsorb fluoride ions in water.
By using defluorination agents or a combination of defluorination processes, the fluoride ion concentration can be reduced to below 0.1ppm, meeting the prescribed emission standards, or meeting the reuse standards, thereby reducing the corrosive effects of fluoride ions on equipment.
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