Difference Between Adsorbent and Absorbent

Published on January 2017 | Categories: Documents | Downloads: 66 | Comments: 0 | Views: 683
of 4
Download PDF   Embed   Report

Comments

Content

Difference Between Adsorbent and Absorbent Adsorbent vs Absorbent Every one is aware of the word absorbent but might have not heard about adsorbent. With a single change of „d‟ in place of „b‟ means a lot of difference between the two. Both adsorbent and absorbent are different physical and chemical processes. Absorbent is the process by which a material absorbs some amount of liquid or gas into it. Adsorbent is a process by which some liquid or gas gets accumulated on the surface of a solid material. Absorbent is a process by which a substance takes in another substance. Absorbent can also be stated as a condition where the ions, atoms or molecules enter some liquid, solid or gas material. Absorption can also be said to the process by which the energy of a photon is absorbed by another entity. Unlike absorbent that is related to volume, Adsorbent is related to surface. Adsorbent is just the opposite of absorbent where the gas or liquid is not absorbed but only forms on the surface of the material. Adsorbent is widely used in industrial applications like activated charcoal, water purification and synthetic resins. In absorption, something moves inside an object whereas in adsorbent, the substance forms a layer on the surface of an object. Adsorption involves adhesion and absorption involves dissolution or diffusion. In absorbent materials, the atoms, molecules or particles are taken internally. On the other hand, the particles, atoms and molecules adhere to the surface only in Adsorbent materials. The molecules are retained only on the surface. Absorption can also be called as filling the pores as the molecules go deep into the body.

Most people are familiar with the term "absorbent" whereas "adsorbent" is often mistaken for a misprint of the word absorbent. The substitution of the "b" by a "d" makes the whole difference in these two words. A material said to be absorbent indicates its ability to carry a certain amount of liquid in its interstice, or little chamber like in a sponge. In the case of a textile fabric, the yarn itself can act like a mini sponge. Also the space between the yarns can be sufficiently tight to trap water and immobilize it due to the surface tension of the water. Yarns of fabric can be made to create additional "traps" for water by brushing. Now, what about adsorption, with a “d”? The word adsorption was introduced to illustrate the concept of „‟chemical absorption‟‟ which occurs when a substance is caught either in nanopores or to the surface of a substrate by low energy (Van der Waal Forces). This is the principle used for activated carbon filter where billions of tiny pores will clean contaminants from a passing fluid. These contaminants can be extracted fairly easily by a steam process. The more one tries to explain the difference between absorption and adsorption, the more it appears that both concepts are in fact very similar. The main difference is that adsorption refers to trapping substances on a nanometric scale (1X10-9). So from now on you may disregard the word adsorption from your vocabulary and use only absorption to express the capacity to hold a liquid within a structure. Adsorption - Is a process that occurs when a gas or liquid accumulates on the surface of a solid or, more rarely, a liquid forming a molecular or atomic film It is different from absorption, in which a substance diffuses into a liquid or solid to form a solution. The term sorption encompasses both processes, while desorption is the reverse process.

Adsorption is operative in most natural physical, biological, and chemical systems, and is widely used in industrial applications such as activated charcoal, synthetic resins and water purification. Adsorption, ion exchange and chromatography are sorption processes in which certain adsorptives are selectively transferred from the fluid phase to the surface of insoluble, rigid particles suspended in a vessel or packed in a column. Similar to surface tension, adsorption is a consequence of surface energy. In a bulk material, all the bonding requirements (be they ionic, covalent or metallic) of the constituent atoms of the material are filled. But atoms on the (clean) surface experience a bond deficiency, because they are not wholly surrounded by other atoms. Thus it is energetically favourable for them to bond with whatever happens to be available. The exact nature of the bonding depends on the details of the species involved, but the adsorbed material is generally classified as exhibiting physisorption or chemisorption. American Society for Testing and Materials(ASTM) Definitions: taken from "Standard Test Methods for Sorbent Performance of adsorbents – ASTM Designation F726 – 99." Sorbent: "An insoluble material or mixture of materials used to recover liquids through the mechanisms of Absorption or Adsorption or both." Adsorbent: "An insoluble material that is coated by a liquid on its‟ surface including pores and capillaries without swelling more than 50% in excess liquid."

Absorbent: "A material that picks up and retains a liquid distributed throughout its‟ molecular structure causing the solid to swell (50% or more). The absorbent is at least 70% insoluble in excess fluid". 1. Absorbent is the process by which a material absorbs some amount of liquid or gas into it. Adsorbent is a process by which some liquid or gas gets accumulated on the surface of a solid material. 2. Unlike absorbent that is related to volume, Adsorbent is related to surface. 3. Absorbent can also be stated as a condition where the ions, atoms or molecules enter some liquid, solid or gas material. 4. Absorption can also be said to the process by which the energy of a photon is absorbed by another entity. 5. In absorption, something moves inside an object whereas in adsorption, the substance forms a layer on the surface of an object. 6. Adsorption involves adhesion and absorption involves dissolution or diffusion. 7. In absorbent materials, the atoms, molecules or particles are taken internally. On the other hand, the particles, atoms and molecules only adhere to the surface in Adsorbent materials.

Sponsor Documents

Or use your account on DocShare.tips

Hide

Forgot your password?

Or register your new account on DocShare.tips

Hide

Lost your password? Please enter your email address. You will receive a link to create a new password.

Back to log-in

Close