Colloidal particles of a colloidal solution carry either positive or negative charge, which makes them good conductors. This property of colloids is made use of in several applications. Some of the applications are given below:
(a) Rubber Plating : This involves electro-deposition of negatively charged rubber particles from rubber sol on handles of different tools, rubber gloves etc.
(b) Sewage Disposal : The sewage water contains impurities, which have colloidal dimensions, carry charge and therefore, do not settle down. These particles can be removed by electrophoresis. The sewage water is passed through a tunnel fitted with two electrodes. A high potential difference is applied when all the colloidal particles move to the oppositely charged electrodes, get neutralised and are coagulated.
(c) Cottrell Smoke Precipitator : A number of industries release large quantity of smoke into the air causing air pollution. The smoke contains unburnt colloidal carbon particles. It can be made free of colloidal particles by installing cottrell precipitator in the chimney of an industrial unit releasing smoke. It consists of two metal rods charged to high potential difference of the order of `30,000` V. The carbon particles get deposited and finally precipitated down while the gases free from carbon particles leave the chimney.
(d) Artificial Rain : Clouds consist of colloidal water particles dispersed in air. They carry charge. When oppositely charged colloidal particles are sprayed over clouds, the water particles get neutralised and are coagulated into bigger water drops causing artificial rain.
(e) Purification of Water : Colloidal particles present in impure water can be coagulated by adding small amount of potash alum `K_2SO_4. Al_2(SO_4)_3 .24H_2O`. The ionic species furnished by alum cause coagulation of colloidal impurities.
(f) Formation of Delta : The muddy river water contains colloidal particles of sand and clay, which carry negative charge. The sea water, on the other hand contains positive ions such as `Na^+`, `Mg^(2+)` and `Ca^(2+)`. As the river water meets seawater, these ions discharge the sand or clay particles, which are precipitated as `text(delta)`.
(g) Foods : Milk is an emulsion of butterfat in water protected by a protein, casein. Salad dressing, gelatin desserts, fruit jellies and whipped cream are other examples. Bread, bun, cake are dispersion of air in baked dough.
(h) Medicines : Medicines in finely divided colloidal form are more effective and are easily absorbed in our system. Many ointments such as skin ointment, lotion, creams and antibiotics such as penicillin and streptomycin are produced in colloidal form.
Colloidal particles of a colloidal solution carry either positive or negative charge, which makes them good conductors. This property of colloids is made use of in several applications. Some of the applications are given below:
(a) Rubber Plating : This involves electro-deposition of negatively charged rubber particles from rubber sol on handles of different tools, rubber gloves etc.
(b) Sewage Disposal : The sewage water contains impurities, which have colloidal dimensions, carry charge and therefore, do not settle down. These particles can be removed by electrophoresis. The sewage water is passed through a tunnel fitted with two electrodes. A high potential difference is applied when all the colloidal particles move to the oppositely charged electrodes, get neutralised and are coagulated.
(c) Cottrell Smoke Precipitator : A number of industries release large quantity of smoke into the air causing air pollution. The smoke contains unburnt colloidal carbon particles. It can be made free of colloidal particles by installing cottrell precipitator in the chimney of an industrial unit releasing smoke. It consists of two metal rods charged to high potential difference of the order of `30,000` V. The carbon particles get deposited and finally precipitated down while the gases free from carbon particles leave the chimney.
(d) Artificial Rain : Clouds consist of colloidal water particles dispersed in air. They carry charge. When oppositely charged colloidal particles are sprayed over clouds, the water particles get neutralised and are coagulated into bigger water drops causing artificial rain.
(e) Purification of Water : Colloidal particles present in impure water can be coagulated by adding small amount of potash alum `K_2SO_4. Al_2(SO_4)_3 .24H_2O`. The ionic species furnished by alum cause coagulation of colloidal impurities.
(f) Formation of Delta : The muddy river water contains colloidal particles of sand and clay, which carry negative charge. The sea water, on the other hand contains positive ions such as `Na^+`, `Mg^(2+)` and `Ca^(2+)`. As the river water meets seawater, these ions discharge the sand or clay particles, which are precipitated as `text(delta)`.
(g) Foods : Milk is an emulsion of butterfat in water protected by a protein, casein. Salad dressing, gelatin desserts, fruit jellies and whipped cream are other examples. Bread, bun, cake are dispersion of air in baked dough.
(h) Medicines : Medicines in finely divided colloidal form are more effective and are easily absorbed in our system. Many ointments such as skin ointment, lotion, creams and antibiotics such as penicillin and streptomycin are produced in colloidal form.