L'alumine activée, une forme partiellement déshydratée de l'oxyde d'aluminium (Al₂O₃), joue un rôle crucial dans diverses applications environnementales. Sa structure poreuse et sa surface élevée en font un excellent adsorbant, capable de capturer une large gamme de polluants de l'air et de l'eau.
Fonctionnement de l'alumine activée :
La structure unique de l'alumine activée est la clé de son efficacité. Elle se compose d'un réseau de pores interconnectés, créant une vaste surface interne. Lorsqu'elle est exposée à des polluants, ces pores agissent comme de minuscules pièges, liant physiquement les molécules par divers mécanismes, notamment :
Applications environnementales :
L'alumine activée trouve des applications diverses dans la protection de l'environnement, notamment :
Avantages de l'alumine activée :
Résumé :
L'alumine activée est un matériau polyvalent doté d'un immense potentiel en matière de protection de l'environnement. Ses propriétés adsorbantes exceptionnelles, associées à sa réutilisabilité et à sa rentabilité, en font un outil précieux pour nettoyer l'air et l'eau, et atténuer la pollution. Son développement continu et ses applications promettent un environnement plus propre et plus sain pour tous.
Instructions: Choose the best answer for each question.
1. What is the primary reason for activated alumina's effectiveness as an adsorbent?
a) Its high density. b) Its porous structure and high surface area. c) Its ability to dissolve pollutants. d) Its strong magnetic properties.
b) Its porous structure and high surface area.
2. Which of the following is NOT a mechanism by which activated alumina adsorbs pollutants?
a) Physical adsorption b) Chemical oxidation c) Chemisorption d) Ion exchange
b) Chemical oxidation
3. How is activated alumina used in water purification?
a) It removes bacteria and viruses. b) It reduces the pH of acidic water. c) It removes fluoride, arsenic, and heavy metals. d) It adds chlorine to disinfect water.
c) It removes fluoride, arsenic, and heavy metals.
4. Which of the following is a key advantage of using activated alumina?
a) It is a permanent solution to pollution. b) It is non-toxic and biodegradable. c) It can be regenerated for repeated use. d) It is completely inert and unaffected by chemicals.
c) It can be regenerated for repeated use.
5. Which of the following is NOT a common application of activated alumina?
a) Air purification b) Water purification c) Fuel production d) Desiccant
c) Fuel production
Task: A factory releases sulfur dioxide (SO₂) into the air. You are tasked with designing a system to remove SO₂ from the exhaust using activated alumina.
Considerations:
Develop a basic design for your system, including the following:
**System Design:** **Components:** * **Adsorption Tower:** A cylindrical vessel filled with activated alumina. * **Exhaust Inlet:** Entry point for the factory's exhaust containing SO₂. * **Air Outlet:** Exit point for clean air after SO₂ removal. * **Regeneration Unit:** A separate chamber for heating the spent activated alumina. **Process Flow:** 1. The factory exhaust enters the adsorption tower. 2. SO₂ molecules adhere to the activated alumina due to their strong affinity. 3. Clean air exits the adsorption tower. 4. Once the activated alumina becomes saturated with SO₂, it is transferred to the regeneration unit. **Regeneration Process:** 1. The spent activated alumina is heated to a high temperature. 2. The heat drives off the adsorbed SO₂ molecules, restoring the adsorbent capacity. 3. The regenerated activated alumina is then returned to the adsorption tower. **Explanation:** The system operates by capturing SO₂ from the exhaust using activated alumina. The adsorbed SO₂ is then removed through regeneration, allowing the activated alumina to be reused. This design is cost-effective due to the reusability of the material and its high efficiency in SO₂ removal.
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