Absorption (chemistry): Difference between revisions
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In [[chemistry]], '''absorption''' is a process by which a substance incorporated in one state is transferred into another substance of a different state (e.g., | In [[chemistry]], '''absorption''' is a process by which a substance incorporated in one state is transferred into another substance of a different state (e.g., [[gas]]es being absorbed by a [[liquid]] or liquids being absorbed by a [[solid]]). As an industrial process, the most commonly encountered use of absorption is for the separation and/or purification of a gas mixture by the absorption of part of the mixture in a [[solvent]]. | ||
==Types of absorption== | |||
Absorption may be either a physical or a chemical process: | |||
'''''Physical absorption''''' of a gas or part of a gas mixture in a liquid solvent involves the mass transfer that occurs at the interface between the gas and the liquid and the rate at which the gas diffuses into the liquid. | |||
:An example of physical absorption of a gas into a liquid is the absorption of [[ammonia]] (NH<sub>3</sub>) into [[water]] (H<sub>2</sub>). Another example is the separation of low [[molecular weight]] [[gas]]es such as [[propane]] (C<sub>3</sub>H<sub>8</sub>) and [[butane]] (C<sub>4</sub>H<sub>10</sub>) from a [[hydrocarbon]] gas mixture of [[methane]] (CH<sub>4</sub>), [[ethane]] (C<sub>2</sub>H<sub>6</sub>), propane and butane by absorbing the propane and butane in a solvent that is a mixture of much higher molecular weight hydrocarbon liquids. | |||
Revision as of 18:35, 21 February 2010
In chemistry, absorption is a process by which a substance incorporated in one state is transferred into another substance of a different state (e.g., gases being absorbed by a liquid or liquids being absorbed by a solid). As an industrial process, the most commonly encountered use of absorption is for the separation and/or purification of a gas mixture by the absorption of part of the mixture in a solvent.
Types of absorption
Absorption may be either a physical or a chemical process:
Physical absorption of a gas or part of a gas mixture in a liquid solvent involves the mass transfer that occurs at the interface between the gas and the liquid and the rate at which the gas diffuses into the liquid.
- An example of physical absorption of a gas into a liquid is the absorption of ammonia (NH3) into water (H2). Another example is the separation of low molecular weight gases such as propane (C3H8) and butane (C4H10) from a hydrocarbon gas mixture of methane (CH4), ethane (C2H6), propane and butane by absorbing the propane and butane in a solvent that is a mixture of much higher molecular weight hydrocarbon liquids.