Factors Affecting Adsorption of Gases on Solids

There are five states of matter known to date in the chemistry sphere. Amongst these, four states of matter are natural. Humans have introduced the last or the fifth matter. The natural states of matter are gases, liquids, solids and plasma.

The fifth state of matter is Bose-Einstein condensates. The Earth is an amalgamation based on the interaction between these matters. So, knowing these interactions is as important as knowing the matters. One such interaction is the adsorption of gases on solids. 

In the simplest sense, the adsorption of gases and solids is the interaction on the surface. Let us understand the term in detail. With this, we will also understand its types and the factors affecting the adsorption of gases on solids.

What Is Adsorption?

Adsorption is the process where the molecules of a matter interact with others on the surface. It is the concentration of one matter on another matter’s surface. Here, the interaction of the matters takes place on the surface. There is a wide concentration of one substance or matter on the surface of another. 

There are two components of adsorption. In adsorption, the molecules of matter that are adsorbed on surfaces are called adsorbate. The surface of the matter that adsorbs these molecules is called adsorbent. 

In adsorption, four main factors affect the process. These are:

Temperature: Adsorption ideally happens when the temperature is low. This is due to adsorption being an exothermic process. The surface or the adsorbent remains highly unstable. When the adsorbent absorbs the adsorbates, the energy decreases and heat is released. 

Pressure Factor: An increase in pressure will escalate adsorption. However, no more adsorption will happen once the saturation takes place regardless of the pressure applied. 

Role of Surface: An essential part of adsorption is through the surface. This surface is where the adsorbates or molecules of other matter are adsorbed. The area of the surface escalates the rate of adsorption. 

Liquefiable Gases: In adsorption, liquefiable gases are easier for adoption. This is because adsorption depends on the nature of gases. The molecular forces of liquefiable gases are easier and greater in high temperatures. 

These are the factors that influence the process of adsorption. There are two types of adsorption that have been identified. Let us know these types in detail. 

Two Types of Adsorption

Adsorption can be classified into two types. These are:

Physical Adsorption

Physical adsorption is the adsorption of gases on solid surfaces. Any gas can be adsorbed by solid surfaces in this type of adsorption. Here, the lower the temperature, the more physical adsorption will be. Also, the greater the surface area, the more will be the adsorption. Physical adsorption can be reversed. If the pressure is increased, the gas molecules will be absorbed more. However, if the pressure is decreased, the adsorption will decrease. 

Chemical Adsorption

Chemical adsorption is a type of adsorption where the gases are adsorbed on the surface through chemical bonds. This surface is solid. This type of adsorption highly relies on when a chemical bond takes place.

If there is no chemical bond, the adsorption will not take place. Contrary to physical adsorption, chemical adsorption cannot be reversed. This is because the chemical bonds are irreversible. For chemical adsorption, increased temperature is necessary. Also, the increase in the surface area promotes increased chemical adsorption. 

These are the two types of adsorption that take place. 

Affecting Factors for Adsorption of Gases on Solids

For the adsorption of gases on solids, various factors affect its processing. These factors are mainly indicators of how well the adsorption is going on. Below are the factors that affect the adsorption of gases on solids:

Surface Area of Absorbent

Absorbent or the surface where the gas molecules get adsorbed is a crucial part of the process of adsorption. The area and the nature of the solid surface matter for adsorption of gases on solids. The wider the area of the absorbent, the rate of adsorption of gases on solids will increase. The solid absorbent must be efficiently porous in nature for the gas molecules to adsorb. Among the variety of absorbents, silica and charcoal are considered ideal absorbents. 

Temperature Variations

Temperature is another important factor that affects the adsorption of gases on solids. To continue adsorption, the temperature must continue to increase. With an increase in the temperature, the adsorption would increase too. As the temperature decreases, adsorption would decrease as well. The temperature does not play a role when saturation occurs. Regardless of the increase in temperature, the adsorption would stop if saturation occurred. 

Characteristics of Gas

The adsorption of gases on solids relies on the types or characteristics of the gases. The liquefiable gases are easier to adsorb than the other types of gases. This is because the molecular force of these gases is great at a critical temperature. However, this is only applicable for physical adsorption. 

Activating Solid Absorbent

The adsorption of gases on solids depends on the activation of the solid absorbent. This means increasing the efficiency of the adsorbent to adsorb more gas molecules. This activation can be done through electroplating. In electroplating, the metal particles are deposited on the solid surface. Activation can also be done by the segregation of adsorbents in particles. However, dividing into particles may lead to difficulties in absorbing gas molecules. 

These are some major factors that influence the adsorption of gases on solids. Regulating these factors will efficiently execute the adsorption of gases on solids.

Conclusion

The world is built with five matters or states of matter. The four natural states of matter are solids, liquids, gas and plasma. The fifth and the man-made state of matter is the Bose-Einstein condensates. 

The Earth involves the interaction of these states of matter. One such interaction is the adsorption of gases on solids. Adsorption refers to the interaction of matters on surfaces. Here, the molecules of one matter are adsorped by the surface of another matter. The adsorbed matter is known as adsorbate. The adsorbing surface is known as an adsorbent. 

Adsorption is of two kinds – physical adsorption and chemical adsorption. Several criteria influence the adsorption of gases on solids. These are:

• Surface Area of Absorbent
• Temperature Variations
• Characteristics of Gas
• Activating Solid Absorbent