Which of the following processes is not an example of adsorption applied to gaseous separations ?

ANS:D - Decolouration of yellow glycerene.

The process that is not an example of adsorption applied to gaseous separations is Decolouration of yellow glycerine. Explanation:

1. Recovery of valuable solvent vapors from dilute mixture with air and other gases: This process involves adsorption where the valuable solvent vapors are selectively adsorbed onto a solid adsorbent material while the remaining gases are allowed to pass through. The adsorbed solvent vapors can then be recovered by desorption for reuse. This is a common application of adsorption in gaseous separations, often used in industries such as chemical manufacturing and petrochemical refining.
2. Dehumidification of air and gas: Dehumidification involves the removal of moisture from air and gas streams using adsorbent materials. Moisture is selectively adsorbed onto the surface of the adsorbent, allowing dry air or gas to pass through. This is a typical application of adsorption in gaseous separations, commonly used in air conditioning systems, compressed air systems, and gas processing industries.
3. Removal of objectionable odor and impurities from industrial gases: Adsorption is frequently used to remove odorous compounds and impurities from industrial gas streams. Adsorbent materials with specific affinity for the target compounds adsorb them from the gas phase, resulting in purified gas streams. This process is commonly employed in industries such as wastewater treatment, chemical manufacturing, and environmental remediation.
4. Decolouration of yellow glycerine: Decolouration typically involves processes such as filtration, precipitation, or chemical treatment to remove colorants from glycerine. Adsorption is not commonly employed for decolouration purposes in glycerine processing. Instead, other methods are usually utilized to achieve the desired color removal.