Applications of Colloids: According to Thomas Graham, the substances that diffuse through the animal membrane are called crystalloids such as salt, and urea solution. Those substances which do not diffuse through the animal membrane are called colloids. However, this classification of Thomas Graham is not correct because salt behaves as a crystalloid in the water while as a colloid in alcohol. We will answer these questions in this article along with the application of colloidal solutions.

Why does the sky look blue? What causes the formation of the delta? Can you make artificial rain? Let us explore the answer to all these questions in this. In this article, you will understand the meaning and examples of colloids, their applications in pharmacy, food articles, the application of colloids in colloid water treatment, zeta potential in colloid science and more.

What are Colloids? 

Colloids are heterogeneous systems having a particle size ranging from \(1\,{\text{nm}} – 1000\,{\text{nm}}\). It consists of two phases, i.e., dispersed phase and a dispersion medium.

(i) Dispersed Phase: The substance present in the form of colloidal particles in the colloidal system is called the dispersed phase.

(ii) Dispersion Medium: The medium in which the colloidal particles are dispersed is called dispersion medium.

Example: In a colloidal solution of ferric hydroxide in water, ferric hydroxide is the dispersed phase, and water is the dispersion medium.

Some examples of colloids are cheese, butter, jellies, paints, cell fluids, and muddy water.

Colloids are found to be useful in daily use and industrial applications. Some typical applications of colloids are described below.

Applications of Colloid in Pharmacy

A large number of medicines and pharmaceutical preparations are colloidal. Some of them are emulsions adsorbed by the body tissue and easily assimilated due to the large surface area. Therefore they are more effective.

Examples: Argyrol is a silver soul used as an eye lotion. Colloidal antimony is used for curing kala-azar. Colloidal gold is used as an intramuscular injection. Milk of magnesia, an emulsion, is used as an antacid to reduce acidity in the stomach. Antibiotics such as penicillin, streptomycin, etc., are usually injected into the body in colloidal forms.

Applications of Colloid in Food Articles

Many constituents of our food are colloidal solutions in nature. For example, milk, starch, proteins, and fruit jellies are colloids. Milk is an emulsion of butterfat in water, stabilised by milk protein (casein). Ice cream is a dispersion of colloid ice particles in cream. Similarly, bread consists of air dispersed in Baker dough.

Applications of Colloids in Water Treatment

River lakes and canal water contain suspended and soluble particles in the form of colloids. This matter cannot be separated by sedimentation or filtration. 

The precipitation of colloidal impurities present in water can be done by adding certain electrolytes like alum. The negatively charged colloidal particles of impurities get coagulated by the \({\text{A}}{{\text{l}}^{3 + }}\)ions into aluminium hydroxide and settle down. Then the pure water is decanted.

Application of Colloids in Rubber Industry

The latex obtained from a rubber tree is an emulsion consisting of a dispersion of negatively charged rubber particles in water. On boiling, the latex of the rubber particles gets coagulated. The coagulated mass is vulcanised and sold as natural rubber. Rubber plated articles can be prepared directly from latex by electrically deposing the negatively charged rubber particles over the articles to be rubber plated by making the articles an anode in the rubber plating bath.

Application of Colloids in Sewage Disposal

Sewage water contains dirt and mud, which are colloidal and carry electrical charges. These particles are removed by electrophoresis. In this method, sewage water is passed through a tunnel fitted with metallic electrodes and maintained at a high potential difference. The colloidal particles present in the sewage water migrate to the oppositely charged electrode and get coagulated. The coagulated colloidal waste can be used as manure.

Application of Colloids in Smoke Precipitations

Smoke is a dispersion of fine dust and carbon particles in the air. These dispersions of suspended particles of colloidal dimensions are electrically charged. Therefore, it can be removed from the air by electrical precipitation using a high voltage smoke precipitator called Cottrell precipitator. In this method, smoke is allowed to pass through a chamber having a number of metal plates attached to a metal wire connected to a source of high potential. Charged particles of smoke get attracted by oppositely charged electrodes, get precipitated after losing their charge, and the hot air passes through the chimney. The dust particles are also removed in this process.

Application of Colloids in Photography

A colloidal solution of silver bromide in gelatine is applied on a glass plate or celluloid films or paper to form a sensitive plate in photography.

Application of Colloids in Leather Industry

The process of hardening leather is known as tanning. Tanning contains negatively charged colloidal particles. Animal hides are also colloidal and contain positively charged colloidal particles. When they are soaked in tannin, their mutual coagulation takes place, and leather becomes hard.  

Application of Colloids in Metallurgical Operations

Several metal ores are concentrated by the froth floatation process. This process involves the treatment of pulverised ore in the emulsion of pine oil.

Application of Colloids in Industrial Product

Several industrial products which we use in our daily life are colloidal—examples: Inks, paints, lubricants, synthetic plastics, rubber, and cement.

Application of Colloids in Formation of Delta

Extensive deposits of up slip and clay formed in the sea at the river’s mouth are called delta. The river water contains colloidal particles of sand and clay, which carries a negative charge. The seawater contains many positive ions such as \({\text{N}}{{\text{a}}^ + },{\text{M}}{{\text{g}}^{2 + }}\), and \({\text{C}}{{\text{a}}^{2 + }}\) ions. When the river water meets seawater, the negative charge present on the colloidal sand and clay particles gets neutralised by the positively charged ions present in the seawater. They get coagulated; with time, it takes the shape of the seawater delta.

What is the Reason for Blue Colour of the Sky?

The sky is empty space around the earth and, as such, has no colour. The blue colour of the sky is due to the scattering of blue light by the colloidal particles like dust, nuclei of condensed water, etc., present in the air.

Cleaning Action of Soaps and Detergents

Soap and detergent remove the oil and dust particles from the fabric by forming water-soluble emulsions through adsorption. 

Application of Colloids in Smoke Screen

A smokescreen is a colloidal dispersion of titanium oxide or Silicon tetrachloride.

Some Examples of Colloids in Daily Life

1. Blue colour of the sky: Dust particles present in the atmosphere combine with air to form colloidal solutions and these colloidal particles scatter the blue colour of light, due to which the colour of the sky appears blue to us.

2. Foodstuff: Milk, butter, fruit juice, ice cream etc are colloidal in nature.

3. Formation of delta: Due to the mixing of dust and sand particles in the water of rivers, this water becomes a negatively charged colloid. There are many types of electrolytes in sea water. When river water comes in contact with sea water, these electrolytes coagulate the river water. Due to which the sand particles start accumulating and the sand gets collected at their meeting point which is called delta.

4. Blood

5. Fog, haze and rain

Summary

In this article, you have learnt about the meaning and the applications of colloids. You can now explain the applications of colloids in pharmacy, food articles, rubber industry, smoke precipitator, sewage disposal, photography, leather industry, metallurgical processes and many more.

FAQs

Q.1: Does colloidal solution find applications?
Ans: The applications of colloids are:
a. For creating artificial rain by throwing an oppositely charged sand or common salt to coagulate water particles. 
b. The blue colour of the sky is due to the scattering of light by colloidal dust particles.
c. Purification of water by coagulation of mud particles on adding alum.
d. The formation of the delta is due to the coagulation of sand or clay particles by salt like NaCl present in seawater.

Q.2: What are 5 examples of colloids?
Ans: Five examples of colloids are cheese, butter, jellies, cell fluids and muddy water.

Q.3: How are colloids used in medicine?
Ans: Emulsions are colloids. They are adsorbed by the body tissue and easily assimilated due to the large surface area. Therefore, they are more effective and used in medicines.
Examples: Argyrol is a silver soul used as an eye lotion. Colloidal antimony is used for curing kala-azar. Colloidal gold is used as an intramuscular injection. Milk of magnesia, an emulsion, is used as an antacid to reduce acidity in the stomach. Antibiotics such as penicillin, streptomycin, etc., are usually injected into the body in colloidal forms.

Q.4: What is the importance and uses of colloids?
Ans: Colloids are important in our daily life and industries. The daily use substances like milk, butter, paints, etc., are colloids. Colloids are also used to purify water, smoke screens, photography, rubber and leather industries, etc.

We hope this article on the Application of Colloids has helped you. If you have any queries, drop a comment below, and we will get back to you.”