Main uses of activated alumina
Appearance of activated alumina: Activated alumina is a white spherical porous particle with uniform particle size, smooth surface, high mechanical strength, strong hygroscopicity, unswollen and uncracked after absorbing water, non-toxic, odorless, insoluble in water, ethanol, has strong adsorption to fluorine, and is mainly used for fluoride removal of drinking water in high fluoride areas.
Activated alumina has the ability to selectively adsorb the moisture of gases, water vapor and some liquids. After adsorption saturation, it can be heated to remove water at about 175-315 ° C and revived. Adsorption and revival can be performed multiple times. In addition to being used as a desiccant, it can also adsorb the vapor of lubricating oil from polluted oxygen, hydrogen, carbon dioxide, natural gas, etc. It can also be used as a catalyst and catalyst carrier and color layer analysis carrier.
Activated alumina Under certain operating conditions and regeneration conditions, the drying depth of the product is as high as the dew point temperature below -70 degrees, [Activated alumina use]: This product can be used as a defluorination agent for high-fluoride drinking water (large defluorination capacity), defluorination agent for circulating alkanes in the production of alkylbenzene, deacidification and regeneration agent for transformer oil, used for gas drying in the oxygen production industry, textile industry, electronics industry, drying of automated instrument wind, and in the drying of fertilizers, petrochemical drying and other industries as desiccants, purification agents (dew point up to -40 degrees), and pressure swing adsorption dew point up to -55 degrees in the air separation industry. It is a highly efficient desiccant for deep drying of trace water. It is very suitable for non-thermal regeneration devices.
Relevant introduction to activated alumina for fluoride removal: my country's "Sanitary Code for Drinking Water" stipulates that the fluoride content should not exceed 1.0mg/L. Raw water with high fluoride is often alkaline, and the pH value is often greater than 7.5.
Fluoride removal methods are roughly divided into the following categories:
(1) Adsorption filtration method;
(2) Membrane method;
(3) Flocculation precipitation method;
(4) Ion exchange method.
The main factors affecting the adsorption performance of activated alumina:
(1) Particle size: The smaller the particle size, the higher the adsorption capacity, but the smaller the particle size, the lower the particle strength, which affects its service life.
(2) Raw water pH value: When the pH value is greater than 5, the lower the pH value, the higher the adsorption capacity of activated alumina.
(3) Initial fluorine concentration of raw water: The higher the initial fluorine concentration, the larger the adsorption capacity.
(4) Alkalinity of raw water: The concentration of bicarbonate in raw water is high, and the adsorption capacity will decrease.
(5) Chloride ions and sulfate ions.
(6) Effect of arsenic: Activated alumina has an adsorption effect on arsenic in water. The accumulation of arsenic on activated alumina causes a decrease in the adsorption capacity of fluoride ions, and makes it difficult to elute arsenic ions during regeneration.
How to regenerate activated alumina: The regeneration agent adopts sodium hydroxide solution or aluminum sulfate solution.
The solution concentration of sodium hydroxide regenerant is 0.75% -1%. The consumption of sodium hydroxide can be calculated based on 8-10g solid sodium hydroxide required for each removal of 1g of fluoride, and the amount of regeneration liquid is 3-6 times the volume of the filter material. The solution concentration of aluminum sulfate regenerant is 2-3%, and the consumption of aluminum sulfate can be calculated based on 60-80g solid aluminum sulfate required for each removal of 1g of fluoride.