Bài giảng soil sorbtion

Gases or liquids being incorporated into another material of a different state and adhering to the surface of another molecule.. Ab sorption and Ad sorption Importance of sorption Soil

Gases or liquids being incorporated into another material of a different state and adhering to the surface of another molecule

Ab sorption and Ad sorption

Importance of sorption

Soil sorption

Predictions of contaminant transport

Sorption in filtration

Sorption reactions generally occur over a short period of time, however

if the adsorbed contaminant begins to be incorporated into the structure

of the sorbent , a slow occurring reaction, known as absorption, begins

to take place To be more precise , the difference between adsorption and absorption is that adsorption is the attraction between the outer surface of a solid particle and a contaminant, whereas absorption is the uptake of the contaminant into the physical structure of the solid.

Importance of sorption

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Soil sorption

Distribution of Inorganic contaminants (metals) in soil

soil organic matter

Metals – „aqueous phase“

•  Free metal ions (eg Cd 2+ , Ni 2+ , Zn 2+ , Cr 3+ ) or

•  Complexes (eg, CdSO 40 , ZnCl + , CdCl 3- )

•  Zn 2+ + Cl - = ZnCl + ZnCl + + Cl - = ZnCl 2

Cation exchange capacity CEC

•  The sum of exchangeable cations

soil CEC values The higher is CEC,

higher the adsorption cationic

contaminants to the surface, the higher the adsorption

Sorption of toxic metals

•  General order of preference or cations to adsorb Pb > Cr > Cu > Cd > Ni > Zn

Sorption of cation is influenced by:

CEC, PZC, pH, surface area, Eh, Ionic

strenght

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