form free ionic species, more protons available to saturate metal-binding sites. This
means that the adsorbent surface is further positively charged at higher hydrogen ion
concentrations. The change in pH improves the biosorption rate as reducing pH
provides high numbers of the free binding sites and increases metal uptakes
(Dwivedi 2012). Thorium removal by Aspergillus fumigatus was reported at pH 4
with maximum metal ion removal capacity (Bhainsa and D’Souza 2009).
3.2 The Influence of Initial Concentration of Heavy Metal
The preliminary amount of heavy metal plays a significant role that determines
molecular mass transfer resistances between the molecule and sorbent (Khataee et al.
2013). The influence of the initial amount on metal ion biosorption is analyzed by
using the initial concentration of chromium [Cr (III)/Cr (VI)] ranging from 0 to
500 mgL
À1 . Reduction of Cr (IV) to Cr (III) was observed over 200 mgL
À1 initial
concentration which proves that initial concentration also matters with fungal biomass and contact time (Kim et al. 2011). Trichoderma versicolor fungal biomass
analyzed for biosorption of chromium (VI) was observed at the preliminary amount
of 15–30 mgL
À1 , and chromium uptake was observed at the range of 2.34 mgg
À1 in
the study conducted by Aksu et al. (2007).
3.3 The Influence of Temperature
Temperature is one of the known factors to influence the solidity of the cell wall and
its arrangement and can also cause ionization of chemical moieties. These factors
may concurrently influence the binding sites on isolated fungal species causing a
reduction in heavy metal elimination (Congeevaram et al. 2007). Temperature
affects the adsorption of heavy metals by fungi (Kabbout and Taha 2014). As
mentioned in Table 17.1, most of the heavy metal biosorption using different fungal
species was optimum at the temperature between 20 and 30
C.
3.4 The Influence of Contact Time
Contact time is the length of time the fungi stay in the contaminant. It also plays an
effective role in fungal biosorption indicating the efficiency of biosorbent to remove
pollutants from a contaminated environment. The efficiency of metal adsorption of
the dead mass of Aspergillus niger was evaluated, and quick removal of metal ions
on the interchange in the functional groups presents on the fungal cell surface at the
initial reaction period and further reduction into metal ion adsorption due to intracellular aggregation of the metal particles. Adsorption rate at an initial 5 min for
360
A. Ayele et al.
means that the adsorbent surface is further positively charged at higher hydrogen ion
concentrations. The change in pH improves the biosorption rate as reducing pH
provides high numbers of the free binding sites and increases metal uptakes
(Dwivedi 2012). Thorium removal by Aspergillus fumigatus was reported at pH 4
with maximum metal ion removal capacity (Bhainsa and D’Souza 2009).
3.2 The Influence of Initial Concentration of Heavy Metal
The preliminary amount of heavy metal plays a significant role that determines
molecular mass transfer resistances between the molecule and sorbent (Khataee et al.
2013). The influence of the initial amount on metal ion biosorption is analyzed by
using the initial concentration of chromium [Cr (III)/Cr (VI)] ranging from 0 to
500 mgL
À1 . Reduction of Cr (IV) to Cr (III) was observed over 200 mgL
À1 initial
concentration which proves that initial concentration also matters with fungal biomass and contact time (Kim et al. 2011). Trichoderma versicolor fungal biomass
analyzed for biosorption of chromium (VI) was observed at the preliminary amount
of 15–30 mgL
À1 , and chromium uptake was observed at the range of 2.34 mgg
À1 in
the study conducted by Aksu et al. (2007).
3.3 The Influence of Temperature
Temperature is one of the known factors to influence the solidity of the cell wall and
its arrangement and can also cause ionization of chemical moieties. These factors
may concurrently influence the binding sites on isolated fungal species causing a
reduction in heavy metal elimination (Congeevaram et al. 2007). Temperature
affects the adsorption of heavy metals by fungi (Kabbout and Taha 2014). As
mentioned in Table 17.1, most of the heavy metal biosorption using different fungal
species was optimum at the temperature between 20 and 30
C.
3.4 The Influence of Contact Time
Contact time is the length of time the fungi stay in the contaminant. It also plays an
effective role in fungal biosorption indicating the efficiency of biosorbent to remove
pollutants from a contaminated environment. The efficiency of metal adsorption of
the dead mass of Aspergillus niger was evaluated, and quick removal of metal ions
on the interchange in the functional groups presents on the fungal cell surface at the
initial reaction period and further reduction into metal ion adsorption due to intracellular aggregation of the metal particles. Adsorption rate at an initial 5 min for
360
A. Ayele et al.