M.Auezov South Kazakhstan State University High school: «Natural science-pedagogical» Chair: «Chemistry» PRESENTATION THEME: ADSORPTION Accepted the: Dikanbaуeva A. Group:SP-15-4K Surrendered:Ibragimova S.

ADSORPTION Adsorption is the process in which matter is extracted from one phase and concentrated at the surface of a second phase. (Interface accumulation). This is a surface phenomenon as opposed to absorption where matter changes solution phase, e.g. gas transfer. This is demonstrated in the following schematic.

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If we have to remove soluble material from the solution phase, but the material is neither volatile nor biodegradable, we often employ adsorption processes. Also adsorption has application elsewhere, as we will discuss later. adsorbate: material being adsorbed adsorbent: material doing the adsorbing. (examples are activated carbon or ion exchange resin).

Exchange adsorption (ion exchange)– electrostatic due to charged sites on the surface. Adsorption goes up as ionic charge goes up and as hydrated radius goes down. Physical adsorption: Van der Waals attraction between adsorbate and adsorbent. The attraction is not fixed to a specific site and the adsorbate is relatively free to move on the surface. This is relatively weak, reversible, adsorption capable of multilayer adsorption.

Chemical adsorption: Some degree of chemical bonding between adsorbate and adsorbent characterized by strong attractiveness. Adsorbed molecules are not free to move on the surface. There is a high degree of specificity and typically a monolayer is formed. The process is seldom reversible.Generally some combination of physical and chemical adsorption is responsible for activated carbon adsorption in water and wastewater.

ADSORPTION EQUILIBRIA If the adsorbent and adsorbate are contacted long enough an equilibrium will be established between the amount of adsorbate adsorbed and the amount of adsorbate in solution. The equilibrium relationship is described by isotherms.

Determination of appropriate model: To determine which model to use to describe the adsorption for a particular adsorbent/adsorbate isotherms experiments are usually run. Data from these isotherm experiments are then analyzed using the following methods that are based on linearization of the models.

Adsorbent: Virtually every solid surface has the capacity to adsorb solutes. From the wastewater/water treatment point of view activated carbon (AC) is the adsorbent of choice. AC prepared from many sources: Wood Lignite Coal Nutshells Bone