331
13.2.3 Other Fruit Peels as Biosorbent
Over the years, many researchers have worked on various kinds of waste fruit cortexes as the cheapest and easily available source of biosorbent for heavy metal
removal. Some extensive work was done on mango peel by a group of researchers
from Pakistan. It was found that mango peel waste is able to remove Cd
2+
and Pb
2+
with a maximum absorption capacity of 68.92 and 99.05 mg/g (Iqbal et al. 2009b).
Another reported work shows that mango peel also has the capacity to remove
Cu
2+
, Ni
2+
, and Zn
2+
from constituted metal solutions and genuine electroplating
industry wastewater (Iqbal et al. 2009a). The adsorption capacity of passion fruit
shell as compared to Citrus maxima peel and sugarcane bagasse for the removal of
Cu
2+
, Cd
2+
, Ni
2+
, and Pb
2+
showed that the Citrus maxima peel and passion fruit shell
gave the highest maximum adsorption capacity (Chao et al. 2014).
Pomelo peel, the white albedo, was separated from the peel, coarsely chopped,
washed, and dried to be used as biosorbent for Cu
2+
removal, and it showed that the
maximum adsorption capacity is 19.7 mg g
−1
(Tasaso 2013). A study on saponified
muskmelon peel showed maximum adsorption capacity of 0.81 mol k
−1
g for Pb
2+
.
Muskmelon peels were found to contain pectic acid that is responsible for the uptake
of lead ions (Huang and Zhu 2013).
Another type of fruit that is highly consumed around the world is grapefruit.
Grapefruit peel activated with ZnCl 2 has been proven to remove lead ions (Pei and
Liu 2011). The efficiency of grapefruit peel as an adsorbent was further investigated
and shown to be able to remove U(IV) from aqueous solutions with an adsorption
capacity of 140.79 mg g
−1
. The biosorbent was also found to regenerate using
0.05 mol L
−1
HCL solution at least three times with 80% recovery (Zou et al. 2012).
In a comparative study between citrus fruits, apples, and grapes, citrus fruits gave
the best adsorption capacity for Cd
2+
in conjunction with physical stability (Schiewer
and Patil 2008). Al-Qahtani (2016) in his study compared kiwi, banana, and tangerine waste fruit cortexes for the removal of Cd
2+
, Cr
3+
, and Zn
2+
. In terms of adsorption capacity, it was found that the adsorption capacities of banana differed from
kiwi and tangerine waste fruit cortexes for the various heavy metals tested. For
banana, it was reported to be Cr
+3
< Cd
+2
< Zn
+2
, whereas it was Cd
+2
< Cr
+3
< Zn
+2
for kiwi and tangerine.
13.3 Heavy Metal Adsorption Mechanisms for Waste
Fruit Cortexes
One of the most economical methods to treat wastewater for heavy metal content is
through adsorption process. The process is simple and adaptable for small industries. Moreover, usage of biosorbent as the source of adsorbent greatly reduces the
cost and increases the ease of operation, making the method attractive for small
holders instead of dumping untreated wastewater unscrupulously. The metal
13 Waste Fruit Cortexes for the Removal of Heavy Metals from Water
13.2.3 Other Fruit Peels as Biosorbent
Over the years, many researchers have worked on various kinds of waste fruit cortexes as the cheapest and easily available source of biosorbent for heavy metal
removal. Some extensive work was done on mango peel by a group of researchers
from Pakistan. It was found that mango peel waste is able to remove Cd
2+
and Pb
2+
with a maximum absorption capacity of 68.92 and 99.05 mg/g (Iqbal et al. 2009b).
Another reported work shows that mango peel also has the capacity to remove
Cu
2+
, Ni
2+
, and Zn
2+
from constituted metal solutions and genuine electroplating
industry wastewater (Iqbal et al. 2009a). The adsorption capacity of passion fruit
shell as compared to Citrus maxima peel and sugarcane bagasse for the removal of
Cu
2+
, Cd
2+
, Ni
2+
, and Pb
2+
showed that the Citrus maxima peel and passion fruit shell
gave the highest maximum adsorption capacity (Chao et al. 2014).
Pomelo peel, the white albedo, was separated from the peel, coarsely chopped,
washed, and dried to be used as biosorbent for Cu
2+
removal, and it showed that the
maximum adsorption capacity is 19.7 mg g
−1
(Tasaso 2013). A study on saponified
muskmelon peel showed maximum adsorption capacity of 0.81 mol k
−1
g for Pb
2+
.
Muskmelon peels were found to contain pectic acid that is responsible for the uptake
of lead ions (Huang and Zhu 2013).
Another type of fruit that is highly consumed around the world is grapefruit.
Grapefruit peel activated with ZnCl 2 has been proven to remove lead ions (Pei and
Liu 2011). The efficiency of grapefruit peel as an adsorbent was further investigated
and shown to be able to remove U(IV) from aqueous solutions with an adsorption
capacity of 140.79 mg g
−1
. The biosorbent was also found to regenerate using
0.05 mol L
−1
HCL solution at least three times with 80% recovery (Zou et al. 2012).
In a comparative study between citrus fruits, apples, and grapes, citrus fruits gave
the best adsorption capacity for Cd
2+
in conjunction with physical stability (Schiewer
and Patil 2008). Al-Qahtani (2016) in his study compared kiwi, banana, and tangerine waste fruit cortexes for the removal of Cd
2+
, Cr
3+
, and Zn
2+
. In terms of adsorption capacity, it was found that the adsorption capacities of banana differed from
kiwi and tangerine waste fruit cortexes for the various heavy metals tested. For
banana, it was reported to be Cr
+3
< Cd
+2
< Zn
+2
, whereas it was Cd
+2
< Cr
+3
< Zn
+2
for kiwi and tangerine.
13.3 Heavy Metal Adsorption Mechanisms for Waste
Fruit Cortexes
One of the most economical methods to treat wastewater for heavy metal content is
through adsorption process. The process is simple and adaptable for small industries. Moreover, usage of biosorbent as the source of adsorbent greatly reduces the
cost and increases the ease of operation, making the method attractive for small
holders instead of dumping untreated wastewater unscrupulously. The metal
13 Waste Fruit Cortexes for the Removal of Heavy Metals from Water