310
C. Bhagat et al.
13.4.1.3 Sorption Techniques
Sorption (adsorption/absorption) processes are widely used to remove the unwanted
constitute from liquid waste generated from community/industries. Basically, sorption means attraction of one molecule in the liquid phase on another solid molecule
in the same phase by the chemical or physical forces. The adsorption process is
the surface phenomenon, whereas absorption is an internal phenomenon. The term
adsorption is generally used to describe the liability of the molecules in the liquid
phase have to adhere to a solid surface. The force field creates a region near the
solid surface either by a physical or chemical process, whose potential energy is low,
resulting in the molecular density increase near the solid surface.
In adsorption phenomenon solute is transported in the bulk and adsorbate movement by the stagnant liquid film surrounding the adsorbent then film diffusion takes
place and adsorbate transport along with the film then pores diffusion take place and
then adsorbate diffusion through the porous structure to the active sites on the surface
(molecular diffusion in the pore and/or in the adsorbent surface). Finally, adsorption
takes place when there is an interaction between adsorbate and porous structure
depending on the nature of the forces involved in the process; it can be divided into
chemical adsorption or physical adsorption (Alsager et al. 2018; Homem and Santos
2011). The forces involved in this phenomenon is relatively week, involving week
Van der Waals interactions forces or loose chemical forces. In chemical adsorption,
the electron transfer and chemical bonds formation between adsorbate and absorbent
occur; these interactions are strong and more specific rather than those existing in
physical adsorption (Ingerslev and Halling-Sørensen 2000).
There are several mechanisms that are involved in the removal of the antibiotic
from the wastewater using adsorbents, including ion exchange, pore filling and π–
π electron interaction (Hu et al. 2019), the electrostatic mechanism (de Oliveira
Carvalho et al. 2019), surface complexation and hydrogen bonding, etc., and they
may occur individually or simultaneously. The removal by ion exchange mechanism
depends upon the size of pollutants and SFG on the biochar used (Zhang et al. 2011;
Premarathna et al. 2019). The pore structure of biochar facilitates the sorption of
contaminants through the pore-filling mechanism (Ahmad et al. 2013).
The adsorption efficiency is dependent not only on adsorbent properties but also
on phase or medium characteristics in which the process is happening. Adsorbent
properties are namely surface area, porosity and pore diameter (Estevinho et al. 2007)
and phase (liquid phase) characteristics such as pH, temperature, type of contamination and their concentration, and also the presence of different organic matters. pH
has a major influence on the removal process because it directly affects the chemical
properties of adsorbent and the surface activity of biochar or adsorbent. Sorption
reaction is an exothermic reaction and hence it is dependent on temperature, with
an increase in temperature adsorption rate is increases. It is important to notice that
the process efficiency is dependent not only on the trace compounds of concern but
also on dissolved naturally occurring organic matter present in any liquid. A major
effect of the organic matter on the removal efficiency is its direct competition to the
C. Bhagat et al.
13.4.1.3 Sorption Techniques
Sorption (adsorption/absorption) processes are widely used to remove the unwanted
constitute from liquid waste generated from community/industries. Basically, sorption means attraction of one molecule in the liquid phase on another solid molecule
in the same phase by the chemical or physical forces. The adsorption process is
the surface phenomenon, whereas absorption is an internal phenomenon. The term
adsorption is generally used to describe the liability of the molecules in the liquid
phase have to adhere to a solid surface. The force field creates a region near the
solid surface either by a physical or chemical process, whose potential energy is low,
resulting in the molecular density increase near the solid surface.
In adsorption phenomenon solute is transported in the bulk and adsorbate movement by the stagnant liquid film surrounding the adsorbent then film diffusion takes
place and adsorbate transport along with the film then pores diffusion take place and
then adsorbate diffusion through the porous structure to the active sites on the surface
(molecular diffusion in the pore and/or in the adsorbent surface). Finally, adsorption
takes place when there is an interaction between adsorbate and porous structure
depending on the nature of the forces involved in the process; it can be divided into
chemical adsorption or physical adsorption (Alsager et al. 2018; Homem and Santos
2011). The forces involved in this phenomenon is relatively week, involving week
Van der Waals interactions forces or loose chemical forces. In chemical adsorption,
the electron transfer and chemical bonds formation between adsorbate and absorbent
occur; these interactions are strong and more specific rather than those existing in
physical adsorption (Ingerslev and Halling-Sørensen 2000).
There are several mechanisms that are involved in the removal of the antibiotic
from the wastewater using adsorbents, including ion exchange, pore filling and π–
π electron interaction (Hu et al. 2019), the electrostatic mechanism (de Oliveira
Carvalho et al. 2019), surface complexation and hydrogen bonding, etc., and they
may occur individually or simultaneously. The removal by ion exchange mechanism
depends upon the size of pollutants and SFG on the biochar used (Zhang et al. 2011;
Premarathna et al. 2019). The pore structure of biochar facilitates the sorption of
contaminants through the pore-filling mechanism (Ahmad et al. 2013).
The adsorption efficiency is dependent not only on adsorbent properties but also
on phase or medium characteristics in which the process is happening. Adsorbent
properties are namely surface area, porosity and pore diameter (Estevinho et al. 2007)
and phase (liquid phase) characteristics such as pH, temperature, type of contamination and their concentration, and also the presence of different organic matters. pH
has a major influence on the removal process because it directly affects the chemical
properties of adsorbent and the surface activity of biochar or adsorbent. Sorption
reaction is an exothermic reaction and hence it is dependent on temperature, with
an increase in temperature adsorption rate is increases. It is important to notice that
the process efficiency is dependent not only on the trace compounds of concern but
also on dissolved naturally occurring organic matter present in any liquid. A major
effect of the organic matter on the removal efficiency is its direct competition to the