Control of Gaseous and Odour Emission | Environmental Engineering

In this article we will discuss about the application of adsorption for control of gaseous and odour emission.

1. Vapour Recovery in Process Industries:

Major applications are in the recovery of solvents from air stream that are free from particulate matter and whose vapor concentrations are above 700 ppm. Activated carbon has been found very effective in adsorption of various organic compounds. Amenability of adsorption of selected hydrocarbons are given in Table 10.7.

2. Deodorisation of Odours Emissions:

Many odorants in low concentrations such as 100 ppb or less are detectable and objectionable and deodorization of such gas streams by solid adsorption is in many instances an effective and economical procedure.

3. Adsorption of H₂S and Carbon Disulphide from Waste Gases of Viscose Production Plants:

Typical pollutants in the waste gases of Viscose rayon industries are hydrogen sulphide and carbon disulphide and these gases can be separated from waste gas stream in single adsorption plant using activated carbon.

4. Adsorption of Sulphur Containing Gases:

Adsorptive separation of various sulphur compounds like H₂S, SO₂ can be achieved by physical adsorption catalysis. Activated carbon serves as a contact catalyst for various reactions of sulphur compounds including air oxidation of H₂S to sulphur of SO₂ to SO₃ or to sulphuric acid and reduction of SO₂ or sulphuric acid by H₂S to produce sulphur(4, 8) Fig. 10.8.

5. Adsorption of No_x:

The methods applied for removal No_x from waste gases are trusted on physical and catalised adsoprtion.

6. Adsorption of Mercury Vapours:

Mercury vapours can be removed by use of adsorbent like activated carbon and ion-exchange resin.

7. Control of Gaseous Radioactive Emission:

Activated carbon adsorption can be used to prevent emission of radioactive gases from nuclear reactors or other sources Radan and radioiodine are examples of adsorptable radioactive gases (9, 10).

8. Gas Musks:

Activated carbon or charcoal are used almost universally in gas mask because they are best all round adsorbent for toxic gases.

For control of evaporative emission:

Activated carbon canisters has been used for carbon of evaporative emission from the fuel tanks and in some cases from the carburettor during the hot soak period after the engine has been turned off (4). Subsequently vapours are descarbed from the carbon by a controlled air purge and the vapors are returned.