Application of colloids

Have you seen water droplets in the fog? Yeah! Fog is also a colloidal substance. The fog is dense with water molecules. Similarly, you are certain to come across several colloids in your everyday life. Thus, this article will discuss the applications and qualities of colloids.

Colloids

Colloids are heterogeneous mixtures of two substances that include minute particles of one component. The dispersed phase is the material in which minute particles are suspended, whereas the dispersion medium is the substance in which the dispersed phase is suspended. In fog, for example, the dispersed phase is water (liquid), while the dispersion medium is composed of various gases. Due to the incredibly tiny size of dispersed phase particles in colloids, we cannot see them with our naked eyes.

Colloids Examples

Numerous colloidal solutions are observable throughout our environment. Cake, milk, bread, butter, ice cream, fruit juices and whipped cream are all colloids. Apart from these, colloids include fog, mist, dirt and so on. The following are some colloidal instances, along with their dispersed phase.

Properties of Colloids

One property that distinguishes colloidal systems from actual solutions is that colloidal particles scatter light. When a light beam, such as that from a flashlight, passes through the colloid, the light is reflected (scattered) by the colloidal particles, allowing the light path to be observed. When a beam of light passes through a real solution (such as salt in water), the light is scattered so little that the light path cannot be seen, and only a small amount of scattered light can be detected by highly sensitive instruments. The scattering of light by colloids, commonly known as the Tyndall effect. 

Colloidal particles selectively absorb ions and acquire electrical charges. All particles of a given colloid carry the same charge (positive or negative) and therefore repel each other. When a potential is applied to the colloid, the charged colloidal particles move towards the oppositely charged electrode; this migration is called electrophoresis. If the charge on the particles is neutralised, they will settle out of suspension. A colloid can be precipitated by the addition of another oppositely charged colloid; the particles attract each other, coagulate and precipitate. Adding soluble ions can precipitate colloids; seawater ions precipitate colloidal sludge, which is dispersed in river water to form deltas. A method developed by FG Cottrell reduces air pollution by using electrostatic precipitators to remove colloidal particles such as smoke, dust and fly ash from exhaust gases. The particles in the lyophobic system are easy to coagulate and precipitate, and the system is not easy to return to the colloidal state. Lyophilic colloids are not easily precipitated and can usually be recovered by adding solvent.

Thixotropy is a property of some gels (semi-solid, gel-like colloids). Thixotropic gels appear solid and hold their shape until subjected to shear (lateral) forces or other disturbances such as shock. It then acts as a sol (a semi-liquid colloid) and flows freely. The thixotropic behaviour is reversible, and if you leave it alone, the soil will slowly turn into a gel. Common thixotropic gels include oil well drilling muds, some printing coatings and inks, and some clays. Thixotropic living clay has caused landslides in parts of Scandinavia and Canada.

Application Of Colloidal Solutions 

Colloids serve a critical role in both nature and daily life. The following sections address some of the most significant applications of colloids:

Colloids in Industrial Applications

 1)  Pharmaceuticals- Colloidal medications are more effective since they are readily absorbed by the body’s tissues.

2) Treatment of wastewater- Colloidal particles of filth, muck, and other organic materials have an electric charge when sewage water is passed over the plates with high potential, the colloidal particles coagulate, and the suspended matter is removed.

3) Purification of water- It is possible to precipitate colloidal pollutants in water by adding certain electrolytes such as alum. Contaminant colloidal particles that are negatively charged are neutralised by the Al3+ ions and settle to the bottom, allowing pure water to be decanted.

4) The cleaning activity of soap- Soap solution that is colloidal in nature. It removes dirt particles by adsorbing or emulsifying the oily substance stuck to the cloth.

5) Formation of the Delta- Colloidal particles of clay, sand and a range of other things may be found in river water. Seawater has a large number of dissolved electrolytes. The colloidal particles in river water coagulate and settle at the contact site when they come into contact with salt water. As a consequence, the level of the riverbed increases. As a consequence, the water flows in a different direction, ultimately forming a delta.

6) Electrical precipitation of smoke- Smoke particles are electrically charged colloidal carbon particles in the air. To precipitate smoke particles, the Cottrell precipitator, which is based on the electrophoresis idea, is utilised. Smoke is allowed to travel through a chamber made up of a succession of metal plates linked to a high-potential source via a metal wire. The heated air escapes via the chimney when charged particles of smoke are attracted to an electrode with an opposing charge. Furthermore, dust particles are removed during this procedure. As a result, the nuisance of smoke in huge industrial cities may be avoided.

7) Techniques of photography- To make sensitive plates in photography, a colloidal solution of silver bromide in gelatin is applied to glass plates, celluloid films, or paper.

8) Rain created by humans- Spraying colloidal dust or sand particles with opposite charges over a cloud may produce artificial rain. Colloidal water droplets in the cloud will be neutralised and coagulated into bigger water drops, creating artificial rain.

9) Rubber production- Negatively charged rubber particles suspended in a colloidal fluid make up latex. Latex coagulation may be used to produce rubber. Rubber-plated items are made by depositing negatively charged rubber particles onto the object to be rubber-plated and then employing the item as an anode in a rubber plating solution. 

10) Smokes-screen- Smoke screens are used to hide things with smoke clouding. Generally used to cover the movement of troops. A smoke screen is also a colloidal system in which titanium oxide particles are dispersed into the air.

Natural Application Of Colloids

Blue Sky:

Light gets dispersed when it meets particles that are smaller than the wavelength of light. The sky’s blue hue is created by light dispersed by minuscule particles in the atmosphere (dust and water particles). The intensity of dispersed light is inversely proportional to the wavelength’s fourth power, according to Rayleigh’s law. Blue light is dispersed the greatest, and red light is scattered the least because blue light has the shortest wavelength and red light has the longest. A blue sky appears in the dispersed blue light that reaches the eye.

Rain, Fog, and Mist:

In nature, fog, mist, and rain are all colloidal. During the winter, moisture in the air condenses on the surface of dust particles, generating microscopic droplets. Due to the colloidal structure of these droplets, they float in the air and condense as mist or fog.

Clouds are a kind of aerosol made up of thousands of small water droplets floating in the air (aerosols). Clouds are the colloidal solution. Colloidal water particles get bigger and larger as they condense in the upper atmosphere, eventually falling like rain. They are electrically charged. When dust particles are exposed to temperatures below their dew point, condensation occurs. When opposingly charged clouds meet, it sometimes rains.

Clouds are sprayed with oppositely charged colloidal dust, sand particles, or silver iodide precipitates to create artificial rain. This spraying procedure neutralises the cloud’s charge, causing the water droplets to coagulate and fall as rain.

Blue Sea:

There are many impurities suspended in seawater, which act as colloids. Due to the Tyndall effect and Rayleigh scattering, these colloidal particles scatter blue light, making them appear blue.

Conclusion:

• A colloid is a complex mixture of minute particles of one material dispersed in a dispersion medium of another substance.
• Colloids are used as thickening agents in lubricants, lotions, toothpaste, and coatings, among other commercial items.
• Colloids are used in the production of paints and inks. Gel ink is used in ball-point pens (liquid-solid colloid).
• The suspended pollutants in natural water are removed by coagulating them with aluminium sulphates (alum) and iron sulphates (ferric sulphates).
• The vast majority of pharmaceuticals are colloidal. To keep muscles alive, colloidal gold and calcium are injected into the body. Argyrol (silver sol) is a topical eye ointment. Albumin, hetastarch, and dextran are some of the other colloids used in medicine.