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Read this article to learn about the conditions, characteristics, factors, role and significance of imbibition.
The term imbibition means the absorption of water by the solid particles of an adsorbent without forming a solution.
The absorption of water by the solid particles of an adsorbent without forming a solution is called Imbibition. In other words the adsorption of water by hydrophilic colloids is known as Imbibition. Solid substance or adsorbent which take part in imbibition are called Imbibants. The liquid which is imbibed is known as Imbibate. Imbibition of water of increases the volume of the imbibant due to which pressure is created known as Imbibitional Pressure (IP).
Condition Necessary for Imbibition:
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1. A water potential gradient should occur between imbibant and liquid imbibe.
2. There should be some force of attraction between imbibant and imbibed liquid.
3. Increase in temperature brings about an increased imbibition.
Characteristics of Imbibition:
1. Adsorption:
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Imbibant substance is an adsorbent. Imbibant holds imbibate (water) by adsorption due to the great force of attraction between the two.
2. Water Potential:
Imbibants have a very high negative water potential. It is called matric potential. Water has (the highest) maximum water potential (maximum being zero).
3. Water Potential Gradient:
When dry imbibant (with high negative water potential) comes in contact with water (maximum water potential), a steep gradient of water potential is created and water diffuses rapidly from its higher potential into the imbibant.
4. Heat of Wetting:
Energy in the form of heat is released during imbibition. It is called heat of wetting.
5. Increase in Volume:
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Volume of the imbibant increases during imbibition e.g. swelling of soaked seeds, swelling of wooden frames during rainy season, etc.
Imbibing Capacity:
Imbibing capacity differs/varies in different imbibants for example, proteins being hydrophilic colloids have maximum imbibing capacity. As compared, starch has lesser and cellulose has the least capacity. As a result, when soaked in water, protein containing seeds e.g. pea swell more than starch storing grains of wheat, maize etc.
Imbibition Pressure:
When the imbibing substance is kept in a confined space, pressure is developed due to the increase in the volume of the imbibant. This is called imbibition pressure. It develops due to the matric potential of the imbibant, hence called matric potential and is denoted as Ѱm (= psi) Ѱm measured in bars or mega pascals (MPa). Now a days, the term imbibition pressure is replaced by the new term matric potential.
Factors Influencing Imbibition:
Capacity as well as the degree of imbibition vary in different imbibing substances and depend up on following factors:
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(a) Texture of the imbibant
(b) Affinity of the imbibant for the imbibate
(c) Temperature
(d) Pressure
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(e) pH of the medium.
Role of Imbibition In Plants:
(i) Imbibition is the first step in the absorption of water by the roots and cells,
(ii) Imbibition of water by cell walls helps to keep the cells moist, and
(iii) Imbibition pressure is helpful in seed germination, growth of seedling through the soil, ascent of sap in plants, etc.
Significance of Imbibition:
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1. It is the dominant and first step of water absorption.
2. Imbibition is the first step of seed germination.
3. Seedling is able to come out of soil due to development of imbibitional pressure.
