Distillation:-Distillation is an operation in which the components of a liquid mixture are separated using thermal energy. It depends upon the difference in boiling points of the individual components. The difference in vapour pressure of the components of a liquid mixture at the same temperature is responsible for separation by distillation. In this operation, liquid and vapour phases are involved. The vapour phase is created by supplying heat to the liquid phase. The concentration of more volatile component of the liquid mixture is higher in vapour phase than in the feed solution, while that of the less volatile component is higher in the liquid phase. When a liquid mixture containing more volatile and less volatile components are heated, more volatile component will vaporize first and the vapours are collected and condensed to get it in pure form.
Leaching:
-Leaching is an operation in which a solid mixture is contacted with a liquid solvent for the removal of one or more constituent of the solid mixture.
-The process of removing a solute from the solid by treating it with a liquid solvent is called leaching.
-This operation is also called as solid-liquid extraction.
-Leaching involves the transfer of soluble component of a solid phase into a relatively non-volatile liquid solvent. The soluble solid from an insoluble solid matter dissolves in the solvent used.
-Leaching may be used either for the production of a concentrated solution of a valuable solid material, or in order to free an insoluble solid from a solute material with it is contaminated.
-Examples of leaching
1) Leaching of gold from its ores by using sodium cyanide solution.
2) Extraction of oil from oilseeds by using hexane as solvent.
3)Extraction of sugar from sugar beats using hot water.