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How the absorption method works to remove fluoride.

Fluoride is both a naturally occurring and added mineral that is found in many water sources. While small amounts of fluoride can be beneficial for dental health, high levels of fluoride in drinking water can be harmful to human health, causing dental and skeletal fluorosis. Therefore, it is important to remove excess fluoride from drinking water to ensure it is safe for consumption.


Two common methods for removing fluoride from drinking water are

activated alumina and corundum.


While both materials are forms of aluminum oxide, they have different properties and are used for different purposes.


Activated alumina is a synthetic material made by heating aluminum hydroxide to high temperatures to remove moisture and increase its surface area. The resulting material has a highly porous structure and a large surface area, which makes it an effective adsorbent for a variety of substances including fluoride. When water is passed through a bed of activated alumina, fluoride ions are attracted to the surface of the material and are adsorbed, leaving the water free of excess fluoride.

Corundum, on the other hand, is a naturally occurring mineral form of aluminum oxide that is found in rocks such as granite and basalt. It is a very hard and durable material, and is commonly used in industrial applications such as abrasives and refractories. Corundum has a unique crystal structure and surface chemistry that gives it a high affinity for fluoride ions. When water is passed through a bed of corundum, fluoride ions are attracted to the surface of the crystal and are adsorbed, leaving the water free of excess fluoride.

While both activated alumina and corundum are effective for removing fluoride from water, there are some differences between the two materials that may make one a better choice for certain applications. For example, corundum has been shown to be more effective than activated alumina at removing fluoride at low concentrations, making it a good choice for water sources with low fluoride levels. Additionally, corundum is more resistant to fouling than activated alumina, meaning it can be used for longer periods of time before needing to be replaced.

However, there are some drawbacks to using corundum for fluoride removal. For one, corundum is a more expensive material than activated alumina, making it less cost-effective for some applications. Additionally, corundum is not as commonly used as activated alumina, so it may be more difficult to find suppliers or expertise in working with the material.


Earthtank™ uses carbon water filters that use corundum for selective absorption to remove fluoride from drinking water. Our filters are designed to provide safe and clean drinking water by removing contaminants such as fluoride, chlorine, and heavy metals. Corundum is an effective and reliable material for fluoride removal, and we have chosen it for our filters due to its high affinity for fluoride ions and resistance to fouling. By using corundum for selective absorption, we are able to provide our customers with a cost-effective and long-lasting solution for removing fluoride from their water sources.


Overall, both activated alumina and corundum are effective methods for removing excess fluoride from drinking water, and both materials have their own unique advantages and disadvantages. Choosing the right material for a particular application will depend on factors such as the concentration of fluoride in the water, the cost of the material, and the availability of suppliers and expertise. Regardless of which material is chosen, removing excess fluoride from drinking water is an important step in ensuring safe and healthy water for consumption.


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