Activated alumina Appearance: Activated alumina is white spherical porous particles, uniform particle size, smooth surface, large mechanical strength, strong hygroscopicity, no swelling or cracking after water absorption to maintain the original state, non-toxic, odorless, insoluble in water, ethanol, It has strong adsorption to fluorine and is mainly used for fluoride removal from drinking water in high fluoride areas. Activated alumina has a selective adsorption capacity for gases, water vapor, and some liquids. After the adsorption is saturated, the water can be removed by heating at about 175-315°C to be revived. Adsorption and reactivation can be performed multiple times. In addition to its use as a desiccant, it also absorbs vapours from contaminated oxygen, hydrogen, carbon dioxide, natural gas, and the like. And it can be used as catalyst and catalyst carrier and chromatographic analysis carrier.
The main factors affecting the adsorption performance of activated alumina:
(1) Particle size: The smaller the particle size, the higher the adsorption capacity. However, the smaller the particle size is, the lower the particle strength will affect its service life.
(2) PH value of raw water: When the PH value is greater than 5, the lower the PH value, the higher the activated alumina adsorption capacity. (3) Initial fluorine concentration of raw water: The higher the initial fluorine concentration, the greater the adsorption capacity.
(3) Raw water alkalinity: The concentration of heavy bicarbonate in raw water is high and the adsorption capacity will be reduced.
(4) Chloride and sulfate ions.
(5) Effects of arsenic: Activated alumina adsorbs arsenic in water. Accumulation of arsenic on activated alumina causes a decrease in fluoride ion adsorption capacity, and it is difficult to elute arsenic ions during regeneration.
How to regenerate activated alumina？The regenerant uses sodium hydroxide solution, but also aluminum sulfate solution.The concentration of sodium hydroxide regenerant solution is 0.75%-1%, the sodium hydroxide consumption can be calculated as 8-10g solid sodium hydroxide per 1g of fluoride removed, and the amount of regeneration liquid is 3-6 times the volume of the filter media. . The solution concentration of the aluminum sulfate regenerant is 2-3%, and the aluminum sulfate consumption can be calculated as 60-80g solid aluminum sulfate per 1g of fluoride removed.