2
1.6 Physicochemical Characteristics of Activated Carbon
12
1.6.1 Physical Characteristics of Activated Carbon
12
1.6.2 Chemical Characteristics of Activated Carbon
15
1.7 Adsorption Mechanism of Activated Carbon
16
1.8 Adsorption Isotherms, Kinetics, and Thermodynamic
Studies of Activated Carbon
19
1.8.1 Adsorption Isotherms
19
1.8.2 Adsorption Kinetics
20
1.8.3 Adsorption Thermodynamics
22
1.9 Conclusions and Future Investigation
23
References
24
Abstract This review provides information on the utilization of activated carbon as
adsorbent for heavy metals removal with a focus on the aqueous phase. Activated
carbon is known to provide large surface area for adsorption. Agricultural residues
(biowastes) which are renewable, highly efficient, and of low cost, have been used
as precursors for synthesis of activated carbon applied in heavy metals uptake. In
this review, details of types of activated carbon, methods of their preparation, and
surface modification and treatment of activated carbon via oxidation, sulfuration,
and nitrogenation are presented. Various factors affecting the performance of activated carbon as well as its physicochemical properties are also discussed. The possible adsorption mechanisms of heavy metal ions typical of different adsorbents are
also summarized in this review. The overview also expounds adsorption isotherms,
adsorption thermodynamics, and adsorption kinetics as they influence the adsorption process.
Keywords Activated carbon · Heavy metals · Surface modification · Adsorption
mechanism · Adsorbent · Adsorbate · Isotherms · Kinetics · Thermodynamics ·
Agricultural wastes
1.1 Introduction
Numerous natural phenomenon and anthropogenic activities have been reported as
the source of heavy metals into the environment. The ions of heavy metals such as
Cr, Co, Cd, Pb, and Hg are injurious to human health and other living forms (Sud
et al. 2008). Several bodies have proposed and set maximum limits for these toxic
heavy metals, specifically in aqueous media. However, rapid industrialization and
urbanization have been promoting the continuous increase in the level of these contaminants in different water systems.
Due to the limitations of the conventional approach (such as ultrafiltration and
reverse osmosis) in the removal of heavy metals, the search for an alternative technique has led to the adoption of activated carbon utilization for the removal of heavy
metals. Besides the attributes activated carbon possesses, such as its large surface
area and high surface reactivity, the associated high cost in its production has been
B. Oladipo et al.
1.6 Physicochemical Characteristics of Activated Carbon
12
1.6.1 Physical Characteristics of Activated Carbon
12
1.6.2 Chemical Characteristics of Activated Carbon
15
1.7 Adsorption Mechanism of Activated Carbon
16
1.8 Adsorption Isotherms, Kinetics, and Thermodynamic
Studies of Activated Carbon
19
1.8.1 Adsorption Isotherms
19
1.8.2 Adsorption Kinetics
20
1.8.3 Adsorption Thermodynamics
22
1.9 Conclusions and Future Investigation
23
References
24
Abstract This review provides information on the utilization of activated carbon as
adsorbent for heavy metals removal with a focus on the aqueous phase. Activated
carbon is known to provide large surface area for adsorption. Agricultural residues
(biowastes) which are renewable, highly efficient, and of low cost, have been used
as precursors for synthesis of activated carbon applied in heavy metals uptake. In
this review, details of types of activated carbon, methods of their preparation, and
surface modification and treatment of activated carbon via oxidation, sulfuration,
and nitrogenation are presented. Various factors affecting the performance of activated carbon as well as its physicochemical properties are also discussed. The possible adsorption mechanisms of heavy metal ions typical of different adsorbents are
also summarized in this review. The overview also expounds adsorption isotherms,
adsorption thermodynamics, and adsorption kinetics as they influence the adsorption process.
Keywords Activated carbon · Heavy metals · Surface modification · Adsorption
mechanism · Adsorbent · Adsorbate · Isotherms · Kinetics · Thermodynamics ·
Agricultural wastes
1.1 Introduction
Numerous natural phenomenon and anthropogenic activities have been reported as
the source of heavy metals into the environment. The ions of heavy metals such as
Cr, Co, Cd, Pb, and Hg are injurious to human health and other living forms (Sud
et al. 2008). Several bodies have proposed and set maximum limits for these toxic
heavy metals, specifically in aqueous media. However, rapid industrialization and
urbanization have been promoting the continuous increase in the level of these contaminants in different water systems.
Due to the limitations of the conventional approach (such as ultrafiltration and
reverse osmosis) in the removal of heavy metals, the search for an alternative technique has led to the adoption of activated carbon utilization for the removal of heavy
metals. Besides the attributes activated carbon possesses, such as its large surface
area and high surface reactivity, the associated high cost in its production has been
B. Oladipo et al.