What are the two main methods for molecular contaminant removal?

The two main methods for molecular contaminant removal are absorption and chemisorption, making this choice the most accurate. Absorption involves the process where molecules from a gas or liquid phase are taken up by a solid or liquid, effectively removing contaminants from the air or fluid. This is often facilitated through materials that have high affinity for the contaminants, such as activated carbon or other chemical adsorbents.

Chemisorption is a more specific form of adsorption where there is a chemical reaction between the contaminant molecules and the adsorbent surface. This typically results in a stronger bond and thus a more effective removal process for certain types of chemical pollutants. This method is highly relevant in air filtration systems designed to capture harmful chemicals from the air effectively.

In contrast, the other options provided focus on different methods or processes that do not primarily target molecular contaminant removal. For instance, filtration and settling are more about separating particles from a fluid or air but may not effectively target gaseous contaminants or those at a molecular level. Similarly, centrifugation and distillation are physical separation processes not specifically designed for molecular contaminants, and evaporation and air filtration pertain more to physical changes and removing particulate matter rather than the chemical or molecular focus required in certain contaminant scenarios.