16
1 A Comprehensive Approach to Heavy Metal Removal by Adsorption …
Arivoli et al. [13] investigated the influence of contact hours on the elimination
of Cu(II) ions by activated carbon at different initial concentrations. They stated that
percentage removal of Cu(II) ions reduced as the initial concentration of Cu(II) ions
raised, but the total amount of Cu(II) ions adsorbed per unit mass of carbon improved
as the concentration of metal ions rises, which implies adsorption is largely based on
the actual concentration of ions. This finding was attributed to the fact that the ratio
of the original concentration of Cu(II) ions to the accessible surface area is small
at lesser concentration, and eventually, the fractional adsorption is regardless of the
actual concentration. Nevertheless, the accessible site of adsorption is less at greater
concentration and thus the percentage of copper ion removal is independent following
initial concentration. They further stated that at all concentrations, equilibrium was
formed 60 min at the contact hours.
1.5 Regeneration/Desorption
For correct dumping and for the re-usability of the adsorbent, metal regeneration
from packed adsorbent is important. Adsorbent re-use tends to maintain the operation
expenses low, and for that intent, it is crucial to regenerate the adsorbent for another
period of use. Nonetheless, the adsorption process requires the absorption of metal
ions which provide a direction for the design of the desorption strategy [142]. Since
pH is such a critical aspect in metal binding, a pH change can enable the metal
to desorb, in order to ensure the adsorbent’s unequalled adsorption efficiency, it is
essential to use the correct eluant for the desorption process.
Shabudeen et al. [139] documented desorption by using (0.25–2) M sodium
hydroxide solution of mercury (II) charged activated carbon. With 2 M of NaOH solution, the researchers recorded a maximum recovery of 99%. They further observed
increased desorption of Hg(II) as compared to the chloride complexes owing to the
establishment of fairly quite stabilized iodide complexes of Hg(II) (Table 1.6).
1.6 Conclusion
In this review, a thorough analysis of related literature reveals that of the five adsorbents reviewed in this study, such as activated carbon, zeolite, peat, chitin and
chitosan. Chitosan and its derivative have the ability to effectively eliminate heavy
metal ions from water and wastewater and to recycle for subsequent use, among
many ways to reduce costs. There are several other reports in the literature about
the removal of heavy metal ions by other adsorbents; however, it is significant to
mention that the overall adsorption ability of different adsorbents varies with the
metal ion size, pH, ionic strength, temperature, concentration, contact time, and
adsorbent constituents. Nevertheless, in spite of the number of articles which have
been reported for heavy metal removal by these adsorbents in recent years, only a
1 A Comprehensive Approach to Heavy Metal Removal by Adsorption …
Arivoli et al. [13] investigated the influence of contact hours on the elimination
of Cu(II) ions by activated carbon at different initial concentrations. They stated that
percentage removal of Cu(II) ions reduced as the initial concentration of Cu(II) ions
raised, but the total amount of Cu(II) ions adsorbed per unit mass of carbon improved
as the concentration of metal ions rises, which implies adsorption is largely based on
the actual concentration of ions. This finding was attributed to the fact that the ratio
of the original concentration of Cu(II) ions to the accessible surface area is small
at lesser concentration, and eventually, the fractional adsorption is regardless of the
actual concentration. Nevertheless, the accessible site of adsorption is less at greater
concentration and thus the percentage of copper ion removal is independent following
initial concentration. They further stated that at all concentrations, equilibrium was
formed 60 min at the contact hours.
1.5 Regeneration/Desorption
For correct dumping and for the re-usability of the adsorbent, metal regeneration
from packed adsorbent is important. Adsorbent re-use tends to maintain the operation
expenses low, and for that intent, it is crucial to regenerate the adsorbent for another
period of use. Nonetheless, the adsorption process requires the absorption of metal
ions which provide a direction for the design of the desorption strategy [142]. Since
pH is such a critical aspect in metal binding, a pH change can enable the metal
to desorb, in order to ensure the adsorbent’s unequalled adsorption efficiency, it is
essential to use the correct eluant for the desorption process.
Shabudeen et al. [139] documented desorption by using (0.25–2) M sodium
hydroxide solution of mercury (II) charged activated carbon. With 2 M of NaOH solution, the researchers recorded a maximum recovery of 99%. They further observed
increased desorption of Hg(II) as compared to the chloride complexes owing to the
establishment of fairly quite stabilized iodide complexes of Hg(II) (Table 1.6).
1.6 Conclusion
In this review, a thorough analysis of related literature reveals that of the five adsorbents reviewed in this study, such as activated carbon, zeolite, peat, chitin and
chitosan. Chitosan and its derivative have the ability to effectively eliminate heavy
metal ions from water and wastewater and to recycle for subsequent use, among
many ways to reduce costs. There are several other reports in the literature about
the removal of heavy metal ions by other adsorbents; however, it is significant to
mention that the overall adsorption ability of different adsorbents varies with the
metal ion size, pH, ionic strength, temperature, concentration, contact time, and
adsorbent constituents. Nevertheless, in spite of the number of articles which have
been reported for heavy metal removal by these adsorbents in recent years, only a