A sorbent is an insoluble material that either absorbs or adsorbs liquids or gases. They are frequently used to remove

pollutant A pollutant or novel entity is a substance or energy introduced into the environment that has undesired effect, or adversely affects the usefulness of a resource. These can be both naturally forming (i.e. minerals or extracted compounds like oi ...

s and in the cleanup of

chemical accident A chemical accident is the unintentional release of one or more Chemical hazard, hazardous chemicals, which could harm human health and the environment. Such events include fires, explosions, and release of toxic materials that may cause people ill ...

s and

oil spill An oil spill is the release of a liquid petroleum hydrocarbon into the environment, especially the marine ecosystem, due to human activity, and is a form of pollution. The term is usually given to marine oil spills, where oil is released into th ...

s. Besides their uses in industry, sorbents are used in commercial products such as

diaper A diaper (, North American English) or a nappy (British English, Australian English, Hiberno-English) is a type of underwear that allows the wearer to urinate or defecate without using a toilet, by absorbing or containing waste products to p ...

s and

odor An odor (American English) or odour ( Commonwealth English; see spelling differences) is a smell or a scent caused by one or more volatilized chemical compounds generally found in low concentrations that humans and many animals can perceive ...

absorbents, and are researched for applications in environmental air analysis, particularly in the analysis of

volatile organic compound Volatile organic compounds (VOCs) are organic compounds that have a high vapor pressure at room temperature. They are common and exist in a variety of settings and products, not limited to Indoor mold, house mold, Upholstery, upholstered furnitur ...

s. The name sorbent is derived from sorption, which is itself a derivation from adsorption and absorption.

Mechanism of action

Sorbents collect specific liquids or gases depending on the composition of the material being used in the sorbent. Some of the most common sorbents used to clean oil spills are made from materials that are both oleophilic and

hydrophobic In chemistry, hydrophobicity is the chemical property of a molecule (called a hydrophobe) that is seemingly repelled from a mass of water. In contrast, hydrophiles are attracted to water. Hydrophobic molecules tend to be nonpolar and, thu ...

, have high surface area through structural designs that include pores and capillaries, and draw in liquid through

capillary action Capillary action (sometimes called capillarity, capillary motion, capillary rise, capillary effect, or wicking) is the process of a liquid flowing in a narrow space without the assistance of external forces like Gravitation, gravity. The effe ...

. Sorbents may be used to collect undesirable ions and act like a reusable ion-exchange resin, composed of charged layers of material that can be heated or otherwise treated to remove pollutants. In this and similar cases, pollutant particles are attracted to the sorbent through electrostatic forces. Some sorbents chemically bind to particles through chemical adsorption, or chemisorption; this process is often more difficult to reverse.

Examples

Sorbents come in various forms and materials, including: * Activated carbon, the most widely used sorbent, which has been known and manufactured since the 19th century, * Molecular sieves, commonly made from

zeolite Zeolites are a group of several microporous, crystalline aluminosilicate minerals commonly used as commercial adsorbents and catalysts. They mainly consist of silicon, aluminium, oxygen, and have the general formula ･y where is either a meta ...

, *

Sponge Sponges or sea sponges are primarily marine invertebrates of the animal phylum Porifera (; meaning 'pore bearer'), a basal clade and a sister taxon of the diploblasts. They are sessile filter feeders that are bound to the seabed, and a ...

s, which can absorb many times their own weight in liquid, *

Polypropylene Polypropylene (PP), also known as polypropene, is a thermoplastic polymer used in a wide variety of applications. It is produced via chain-growth polymerization from the monomer Propene, propylene. Polypropylene belongs to the group of polyolefin ...

fiber mats, which can be employed to absorb oil, *

Cellulose Cellulose is an organic compound with the chemical formula, formula , a polysaccharide consisting of a linear chain of several hundred to many thousands of glycosidic bond, β(1→4) linked glucose, D-glucose units. Cellulose is an important s ...

fiber products used for oil or chemical sorption, * The granular gel material in

s, capable of absorbing multiple times its original weight in

urine Urine is a liquid by-product of metabolism in humans and many other animals. In placental mammals, urine flows from the Kidney (vertebrates), kidneys through the ureters to the urinary bladder and exits the urethra through the penile meatus (mal ...

, * Incontinence pads, which may also incorporate

nonwoven fabric Nonwoven fabric or non-woven fabric is a fabric-like material made from staple fibre (short) and long fibres (continuous long), bonded together by chemical, mechanical, heat or solvent treatment. The term is used in the textile manufacturing in ...

as a sorbent, and *

Desiccant A desiccant is a hygroscopic substance that is used to induce or sustain a state of dryness (desiccation) in its vicinity; it is the opposite of a humectant. Commonly encountered pre-packaged desiccants are solids that absorb water. Desiccant ...

s, which attract water, thereby

drying Drying is a mass transfer process consisting of the removal of water or another solvent by evaporation from a solid, semi-solid or liquid. This process is often used as a final production step before selling or packaging products. To be consider ...

(

desiccating Desiccation is the state of extreme dryness, or the process of extreme drying. A desiccant is a hygroscopic (attracts and holds water) substance that induces or sustains such a state in its local vicinity in a moderately sealed container. The ...

) surrounding materials.

References

* * * * * {{Authority control Desiccants Natural materials Synthetic materials