8 Recovery and Regeneration of Biosorbents
The major advantage of using biosorbents is its reusability. As the adsorbent is
insoluble in the solution, it can be filtered or centrifuged to separate it from the
solution. Then the adsorbate can be separated from adsorbent by desorption process.
As the adsorbate and adsorbent are held together only by temporary interaction, they
can be easily released by reversing the physical or chemical reactions. Alteration of
pH to desorb the adsorbate from the adsorbent is common method used for desorption. The pH is altered from a range of 2–12 for a given period of time to desorb the
adsorbate [9]. Addition of chemicals which have functional groups that react with
the adsorbate will desorb the adsorbate from the adsorbent. This will return the
adsorbent to its previous state in which it can be used for adsorption again. Acids,
bases [25], chelating groups such as EDTA [6] and organic solvents [8] can be used
to recover the adsorbate and regenerate the adsorbent. Regenerated adsorbent can be
used for adsorption process again.
9 Kinetics and Models for Biosorption
For the representation of results, equilibrium data need to be analysed and an
equation is needed to be developed for design purposes. For this, there are several
equilibrium models and isotherms are available. Common isotherms include
Freundlich, Langmuir and Redlich–Peterson isotherms. The common isotherms,
their equation and the graph are presented in the below table [19, 35].
Material and Process Selection for Biosorption
253
The major advantage of using biosorbents is its reusability. As the adsorbent is
insoluble in the solution, it can be filtered or centrifuged to separate it from the
solution. Then the adsorbate can be separated from adsorbent by desorption process.
As the adsorbate and adsorbent are held together only by temporary interaction, they
can be easily released by reversing the physical or chemical reactions. Alteration of
pH to desorb the adsorbate from the adsorbent is common method used for desorption. The pH is altered from a range of 2–12 for a given period of time to desorb the
adsorbate [9]. Addition of chemicals which have functional groups that react with
the adsorbate will desorb the adsorbate from the adsorbent. This will return the
adsorbent to its previous state in which it can be used for adsorption again. Acids,
bases [25], chelating groups such as EDTA [6] and organic solvents [8] can be used
to recover the adsorbate and regenerate the adsorbent. Regenerated adsorbent can be
used for adsorption process again.
9 Kinetics and Models for Biosorption
For the representation of results, equilibrium data need to be analysed and an
equation is needed to be developed for design purposes. For this, there are several
equilibrium models and isotherms are available. Common isotherms include
Freundlich, Langmuir and Redlich–Peterson isotherms. The common isotherms,
their equation and the graph are presented in the below table [19, 35].
Material and Process Selection for Biosorption
253