Before we discuss the colloids around us and their commercial applications, let us recall what they are.
What is a Colloid?
A colloid is a heterogeneous mixture in which the minute particles of one substance are dispersed in another substance, called the dispersion medium. The minute particles here are 1 to 1000 nanometers in diameter but they still remain suspended and do not settle at the bottom of the mixture. Sol, aerosol, foam, emulsion, etc., are some of the types of colloids. In this section, we will see how colloids are present in our everyday items of use and their applications in different fields.
Examples of Colloid
- Most of the food products which we eat today are colloids, including the dairy products. Cake, bread, milk, cream, butter, ice cream, margarine, fruit juices, whipped cream, etc. are colloidal in nature.
- The natural phenomena which we observe such as fog, mist, clouds, and rain are colloids in different forms. Even dust and smoke are colloidal.
- The blue color of the sky can be credited to the suspended dust and water particles in the air which scatter blue light more than any other wavelength. Similarly, seawater is blue because of the colloidal impurities present in it, which also scatter blue light.
- A colloid is present in the fertile soil in the form of clay and humus material. It also plays a vital role in storage and exchange of minerals.
Commercial Applications of Colloid
- A colloid is used as thickening agents in industrial products such as lubricants, lotions, toothpaste, coatings, etc.
- In the manufacture of paints and inks, colloids are useful. In ball-point pens, the ink used is gel (liquid-solid colloid).
- The suspended impurities contained in the natural water are removed by adding sulfates of aluminum (alum) and of iron which coagulates them.
- Most of the medicines are colloidal. Colloidal gold and calcium are injected into the human body for the vitality of the muscles. Argyrol (silver sol) is used as an eye lotion. Albumin, Hetastarch, and Dextran are a few other colloids used in medicine.
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