11
1.4.4 Surface Modification by Coordinated
Ligand Functionalization
Literature has shown that different coordinated ligands have significantly modified
activated carbon characteristics such as textural and chemical properties with the
aim of improving the adsorption capacity of activated carbon (Rivera-Utrilla et al.
2011). Chemical composition of modified activated carbon by coordinated ligand
functionalization is dependent on the ligand employed, and this has been portrayed
to increase surface basicity, negative charge, nitrogen, chlorine, and the sulfur content (Justi et al. 2005; Li et al. 2009). Published articles have demonstrated that
activated carbon with ligands at the surface has increase metal adsorption rate, nonleachability of the ligands into the contaminated solutions and the ease of regeneration of activated carbon ligand modified adsorbents (Rivera-Utrilla et al. 2011).
1.5 Factors Affecting the Performance of Activated Carbon
Performance of activated carbon mainly depends on both the physicochemical properties of its precursors and the production routes (González-García 2018). Activated
carbon parameters that have been found to have significant influence on its performance as adsorbent are summarized in Table 1.4.
1.5.1 Effects of Physical and Operational Parameters
It has been broadly reported that the higher the surface area and pore volume of
activated carbon, the better its performance as an adsorbent (Alslaibi et al. 2013;
Danish and Ahmad 2018; Müller 2010; Roman et al. 2013). With respect to this,
Şentorun-Shalaby et al. (2006) and Alslaibi et al. (2013) reported that the finer the
particle size, the higher the specific surface area and pore volume which in turn
leads to higher adsorption capacity. While investigating the removal and recovery of
lanthanum (La) using different adsorbents, Iftekhar et al. (2018) concluded that
adsorbent materials with functional groups such as amine, carboxyl, and hydroxyl
have higher adsorption capacity and, thus, efficiently removed La over an extensive
range of pH. Also, the effects of phosphoric acid (H 3 PO 4 ) concentrations as activating reagent on the pore structure and surface chemistry of olive stone-based activated carbon were investigated by Yakout and El-Deen (2016). It was reported that
increasing the reagent concentrations increases the surface area and pore volume of
the activated carbon produced; however, the reverse is the case for the yield of activated carbon. The effects of various factors on the properties as well as the performance of activated carbon are shown in Table 1.5.
1 Synthesis of Activated Carbons for Heavy Metals Removal
1.4.4 Surface Modification by Coordinated
Ligand Functionalization
Literature has shown that different coordinated ligands have significantly modified
activated carbon characteristics such as textural and chemical properties with the
aim of improving the adsorption capacity of activated carbon (Rivera-Utrilla et al.
2011). Chemical composition of modified activated carbon by coordinated ligand
functionalization is dependent on the ligand employed, and this has been portrayed
to increase surface basicity, negative charge, nitrogen, chlorine, and the sulfur content (Justi et al. 2005; Li et al. 2009). Published articles have demonstrated that
activated carbon with ligands at the surface has increase metal adsorption rate, nonleachability of the ligands into the contaminated solutions and the ease of regeneration of activated carbon ligand modified adsorbents (Rivera-Utrilla et al. 2011).
1.5 Factors Affecting the Performance of Activated Carbon
Performance of activated carbon mainly depends on both the physicochemical properties of its precursors and the production routes (González-García 2018). Activated
carbon parameters that have been found to have significant influence on its performance as adsorbent are summarized in Table 1.4.
1.5.1 Effects of Physical and Operational Parameters
It has been broadly reported that the higher the surface area and pore volume of
activated carbon, the better its performance as an adsorbent (Alslaibi et al. 2013;
Danish and Ahmad 2018; Müller 2010; Roman et al. 2013). With respect to this,
Şentorun-Shalaby et al. (2006) and Alslaibi et al. (2013) reported that the finer the
particle size, the higher the specific surface area and pore volume which in turn
leads to higher adsorption capacity. While investigating the removal and recovery of
lanthanum (La) using different adsorbents, Iftekhar et al. (2018) concluded that
adsorbent materials with functional groups such as amine, carboxyl, and hydroxyl
have higher adsorption capacity and, thus, efficiently removed La over an extensive
range of pH. Also, the effects of phosphoric acid (H 3 PO 4 ) concentrations as activating reagent on the pore structure and surface chemistry of olive stone-based activated carbon were investigated by Yakout and El-Deen (2016). It was reported that
increasing the reagent concentrations increases the surface area and pore volume of
the activated carbon produced; however, the reverse is the case for the yield of activated carbon. The effects of various factors on the properties as well as the performance of activated carbon are shown in Table 1.5.
1 Synthesis of Activated Carbons for Heavy Metals Removal