261
rest other substances which enable sorption properties toward heavy metal ions. An
experimental study on activated coconut shell with phosphoric acid revealed that
adsorption of Pb is higher than inactivated coconut shell (El-Deen and El-Deen
2016). Another research work converts coconut shell into activated carbon, and the
result shows maximum adsorption capacity of 26.41 mg g
−1
for cadmium ion at
pH 5.5 (Jin et al. 2013).
Peanut shells are also found to be a good adsorbent for heavy metal removal. An
effective Cr
+6
removal at low pH values was also achieved by researchers (Ahmad
et al. 2017). Peanut husk seemed to have efficient adsorption properties toward
heavy metals.
Pistachio hull waste is also considered as a susceptible adsorbent for various
toxic metals. It was reported that Cr
+6
from waste was removed with 98% of efficiency using pistachio hull (Moussavi and Barikbin 2010). Another study explored
adsorption capabilities of pecan shells with different metal ions such as Pb
+2
, Cu
+2
,
and Zn
+2
by applying a number of modification methods to improve removal efficiency which includes carbon dioxide, steam, and acid activation (Bansode
et al. 2003).
Fruit waste material like peel shows remarkable adsorption capacity for various
heavy metals in treatment of different wastewater. Orange peel acts as an efficient
bioadsorbent as it contains cellulose, pectin, hemicelluloses, and lignin in high
amount. Different heavy metals like Zn, Pb, Ni, Cu, and Cd were significantly
removed using orange peel. Studies have stated that chemically modified orange
peel enhances adsorption capacities metal like Pb, Cd, Cu, and Ni. Mosambi or
sweet lime peel dust was capable to adsorb Cr
+6
ions from an aqueous solution
(Saha et al. 2013). Banana peel also shows different degrees of heavy metal removal
for Zn
+2
, Pb
+
2, Cd
+2
, Cu
+2
, and Ni
+2
. A maximum adsorption capacity of 46.1 and
42.1 mg g
−1
for the removal of Ni and Cd was achieved by grapefruit peel (TorabMostaedi et al. 2013).
10.3.7 Industrial Waste
Industrial waste is another cheap source of adsorbent which can be used for heavy
metal removal from wastewater. Synthesis of adsorbent from industrial waste
mainly by-products requires very small processing. Some of the industrial wastes
capable of removing heavy metals from wastewater are fly ash, red mud, lignin,
blast furnace sludge, grape stalks waste, and battery industry waste.
Fly ash, a residue product of coal combustion, has high potential for adsorption
for which it is used in wide range of applications. It can be used as a good substitute
of commercial adsorbents such as zeolite and activated carbon. Adsorption capacities of fly ash depend on the origin from which it is derived as because it has a
variety in chemical composition. Mainly the chemical compositions of fly ash are
silica 60–65%, alumina 25–30%, and magnetite 6–15% which makes it compatible
to be used as an adsorbent. Raw fly has low adsorption capacity which can be
10 Heavy Metal Removal by Low-Cost Adsorbents
rest other substances which enable sorption properties toward heavy metal ions. An
experimental study on activated coconut shell with phosphoric acid revealed that
adsorption of Pb is higher than inactivated coconut shell (El-Deen and El-Deen
2016). Another research work converts coconut shell into activated carbon, and the
result shows maximum adsorption capacity of 26.41 mg g
−1
for cadmium ion at
pH 5.5 (Jin et al. 2013).
Peanut shells are also found to be a good adsorbent for heavy metal removal. An
effective Cr
+6
removal at low pH values was also achieved by researchers (Ahmad
et al. 2017). Peanut husk seemed to have efficient adsorption properties toward
heavy metals.
Pistachio hull waste is also considered as a susceptible adsorbent for various
toxic metals. It was reported that Cr
+6
from waste was removed with 98% of efficiency using pistachio hull (Moussavi and Barikbin 2010). Another study explored
adsorption capabilities of pecan shells with different metal ions such as Pb
+2
, Cu
+2
,
and Zn
+2
by applying a number of modification methods to improve removal efficiency which includes carbon dioxide, steam, and acid activation (Bansode
et al. 2003).
Fruit waste material like peel shows remarkable adsorption capacity for various
heavy metals in treatment of different wastewater. Orange peel acts as an efficient
bioadsorbent as it contains cellulose, pectin, hemicelluloses, and lignin in high
amount. Different heavy metals like Zn, Pb, Ni, Cu, and Cd were significantly
removed using orange peel. Studies have stated that chemically modified orange
peel enhances adsorption capacities metal like Pb, Cd, Cu, and Ni. Mosambi or
sweet lime peel dust was capable to adsorb Cr
+6
ions from an aqueous solution
(Saha et al. 2013). Banana peel also shows different degrees of heavy metal removal
for Zn
+2
, Pb
+
2, Cd
+2
, Cu
+2
, and Ni
+2
. A maximum adsorption capacity of 46.1 and
42.1 mg g
−1
for the removal of Ni and Cd was achieved by grapefruit peel (TorabMostaedi et al. 2013).
10.3.7 Industrial Waste
Industrial waste is another cheap source of adsorbent which can be used for heavy
metal removal from wastewater. Synthesis of adsorbent from industrial waste
mainly by-products requires very small processing. Some of the industrial wastes
capable of removing heavy metals from wastewater are fly ash, red mud, lignin,
blast furnace sludge, grape stalks waste, and battery industry waste.
Fly ash, a residue product of coal combustion, has high potential for adsorption
for which it is used in wide range of applications. It can be used as a good substitute
of commercial adsorbents such as zeolite and activated carbon. Adsorption capacities of fly ash depend on the origin from which it is derived as because it has a
variety in chemical composition. Mainly the chemical compositions of fly ash are
silica 60–65%, alumina 25–30%, and magnetite 6–15% which makes it compatible
to be used as an adsorbent. Raw fly has low adsorption capacity which can be
10 Heavy Metal Removal by Low-Cost Adsorbents