Final Answer:
Carbon dioxide and moisture are removed from air during fractional distillation through a series of purification steps, including adsorption and cooling.
Step-by-step explanation:
In the initial stages of fractional distillation, air undergoes compression and cooling to convert its components into liquids. This process, however, brings along impurities like carbon dioxide (CO2) and moisture. To ensure the purity of the final products, additional purification steps are essential.
One method employed is adsorption, where a molecular sieve or absorbent material selectively captures carbon dioxide and water molecules. Molecular sieves, such as zeolites, possess specific pore sizes that allow them to adsorb these impurities while letting oxygen and nitrogen pass through.
After adsorption, the air is further cooled. At lower temperatures, carbon dioxide and moisture in the air tend to condense and can be removed as liquids. This step is crucial for preventing these impurities from freezing and affecting the efficiency of the subsequent stages of the fractional distillation process.
In summary, the removal of carbon dioxide and moisture from air during fractional distillation involves a combination of adsorption and cooling techniques. These measures are essential to obtain high-purity oxygen and nitrogen as the final products of the process.