Absorption; Assimilation of molecular species throughout the bulk of the solid or liquid is termed as absorption. It is a  bulk  phenomenon. It is endothermic process. It is not affected by temperature.It occurs at a uniform rate.It is same throughout the material.

Adsorption: Accumulation of the molecular species at the surface rather than in the bulk of the solid or liquid is termed as adsorption.It is a surface phenomenon. It is exothermic process. It is favored by low temperature.  .IT steadily increases and reach to equilibrium. Concentration on the surface of adsorbent is different from that in the bulk

Uses

Absorption: The common commercial uses of absorption cycle are absorption chillers for space cooling applications, ice production, cold storage, turbine inlet cooling. High efficiency operation, environmentally friendly refrigerants, clean-burning fuels and few moving parts that require maintenance make absorption a very good choice for consumers. The process of gas absorption by a liquid is used in hydrogenation of oils and carbonation of beverages.

Adsorption: Some of the industrial applications for adsorption are air-conditioning, adsorption chillers, synthetic resin and water purification. An adsorption chiller does not require moving parts and hence is quiet. In pharmaceutical industry applications, adsorption is used as a means to prolong neurological exposure to specific drugs or parts thereof. Adsorption of molecules onto polymer surfaces is used in various applications such as in the development of non-stick coatings and in various bio-medical devices.

Absorption systems use a pair of absorbent/absorbate which are liquid (LiBr/water or water/Ammonia). adsorption systems use a pair of adsorbent/adsorbate which are solid/vapour (Silica Gel, zeolite, activated carbon). the regeneration of both system will need external heat source. I m not aware of any system that combines the two types.

Perhaps, you will be interested by the link to work:

work:https://www.researchgate.net/publication/231092445_Study_of_photoinduced_absorption_by_the_method_of_modified_laser_photothermal_radiometry

Article Study of photoinduced absorption by the method of modified l...

Sorption: The phenomenon in which adsorption and absorption occur simultaneously is called sorption. Mc. Bain introduced a general term sorption describeing both the processes, however adsorption is instantaneous i.e. a fast process while absorption is a slow process.

Reference:Sample Preparation Techniques in Analytical Chemistry

edited by Somenath Mitra

The Pearson Guide to Objective Chemistry for the AIEEE

By Singhal Atul

Dear All.

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