Factors Affecting the Adsorption Performance of Activated Alumina
Activated alumina is generally prepared by heating and dehydrating aluminum hydroxide. Aluminum hydroxide is also called hydrated alumina. Its chemical composition is Al2O3·nH2O. Usually, it can be divided into alumina trihydrate and alumina monohydrate according to the number of crystal water contained. After heating and dehydration of aluminum hydroxide, γ-Al2O3 can be obtained. That is commonly referred to as activated alumina.
1. Use of activated alumina
Activated alumina belongs to the category of chemical alumina, and activated alumina is used for adsorbents, water purifiers, catalysts and catalyst carriers. Activated alumina has selective adsorption capacity for gas, water vapor and moisture in some liquids. After the adsorption is saturated, it can be heated at about 175-315 ℃ to remove water and resurrect. Adsorption and resurrection can be performed multiple times. In addition to being used as a desiccant, it can also absorb the vapor of lubricating oil from polluted oxygen, hydrogen, carbon dioxide, natural gas, etc. And can be used as catalyst and catalyst carrier and chromatographic analysis carrier.
Activated alumina can be used as a defluorination agent for high fluoride drinking water (large defluorination capacity), a defluorination agent for circulating alkanes in the production of alkyl benzene, a deacidification and regenerating agent for transformer oil, used in oxygen production industry, textile industry, electronics industry, etc. Industrial gas drying, automatic instrument air drying, as desiccant and purifying agent in chemical fertilizer, petrochemical drying and other industries (dew point can reach -40 ℃) in the air separation industry, pressure swing adsorption dew point can reach -55 ℃. It is a high-efficiency desiccant for deep drying of trace water, which is very suitable for heatless regeneration devices.
2. 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) pH value of raw water: 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 in raw water: the higher the initial fluorine concentration, the larger the adsorption capacity.
(4) Raw water alkalinity: The high concentration of bicarbonate in raw water will reduce the adsorption capacity.
(5) Chloride and sulfate ions.
(6) Influence 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 it is difficult to elute arsenic ions during regeneration.