unstable carbonyl groups are immediately converted to CO 2 through either hydrolysis or further oxidation by the permanganate ion. Manganese dioxide (MnO 2 ) is
the end product of the reduction of the permanganate oxyanion under neutral to basic
pH conditions by the following reaction:
MnO 4
À þ 2H 2 O þ 3e À ! MnO 2 þ 4OH À
ð7:4Þ
At low pH, reduction of MnO 4
– proceeds to Mn(II):
MnO 4
À þ 8H
þ
þ 5e À ! Mn
2þ
þ 4H 2 O
ð7:5Þ
The Mn(II) cation is soluble in water at concentrations above the regulatory limit
(50 μg/L) when chloride or sulfate counteranions are present.
Permanganate is easily handled, readily available, and it is a strong and versatile
oxidizing agent with a relatively high oxidizing power (Table 7.1), reacting with a
wide range of organic compounds over a wide range of pH. Permanganate oxidation
involves primarily electron transfer in contrast with the Fenton’s reaction and the
persulfate reactions that also involve free radical reaction. Advantages of using
permanganate over other chemical oxidants include: (1) unlike Fenton reactions,
the reactions are not exothermic, (2) pH control is not an issue, (3) catalysts are not
required, (4) free radical scavengers such as carbonates are not required, and
(5) being a mild oxidant, it can be used in association with bioremediation. Permanganates have been successfully used in the oxidation of alkanes, alkenes, aromatic
hydrocarbons, ketones, aldehydes, PAHs, etc. (Achugasim et al. 2014 and references
therein).
7.2.2 Ozonation
Ozone has been used for treating drinking water since the beginning of the twentieth
century (Gerrity et al. 2018), because of its high power to oxidize contaminants and
the innocuous decay products generated in the process (oxygen and water). This
makes the method less toxic compared with other treatments that use, e.g., Cl 2 or
chromic acid. The compound is a powerful oxidant (Table 7.1) and an efficient
bactericide.
Ozone can react by a direct reaction (slow and selective) with an organic
compound P:
O 3ðgÞ ! O 3ðlÞ þ P ! P ox k % 1x10
3 1=ðM sÞ
ð 7:6Þ
or by a radical reaction (rapid and non-selective), accelerated in alkaline media
(Huang et al. 1993; Domènech et al. 2004; Litter 2005; Oppenländer 2003; Glaze
124
M. I. Litter
the end product of the reduction of the permanganate oxyanion under neutral to basic
pH conditions by the following reaction:
MnO 4
À þ 2H 2 O þ 3e À ! MnO 2 þ 4OH À
ð7:4Þ
At low pH, reduction of MnO 4
– proceeds to Mn(II):
MnO 4
À þ 8H
þ
þ 5e À ! Mn
2þ
þ 4H 2 O
ð7:5Þ
The Mn(II) cation is soluble in water at concentrations above the regulatory limit
(50 μg/L) when chloride or sulfate counteranions are present.
Permanganate is easily handled, readily available, and it is a strong and versatile
oxidizing agent with a relatively high oxidizing power (Table 7.1), reacting with a
wide range of organic compounds over a wide range of pH. Permanganate oxidation
involves primarily electron transfer in contrast with the Fenton’s reaction and the
persulfate reactions that also involve free radical reaction. Advantages of using
permanganate over other chemical oxidants include: (1) unlike Fenton reactions,
the reactions are not exothermic, (2) pH control is not an issue, (3) catalysts are not
required, (4) free radical scavengers such as carbonates are not required, and
(5) being a mild oxidant, it can be used in association with bioremediation. Permanganates have been successfully used in the oxidation of alkanes, alkenes, aromatic
hydrocarbons, ketones, aldehydes, PAHs, etc. (Achugasim et al. 2014 and references
therein).
7.2.2 Ozonation
Ozone has been used for treating drinking water since the beginning of the twentieth
century (Gerrity et al. 2018), because of its high power to oxidize contaminants and
the innocuous decay products generated in the process (oxygen and water). This
makes the method less toxic compared with other treatments that use, e.g., Cl 2 or
chromic acid. The compound is a powerful oxidant (Table 7.1) and an efficient
bactericide.
Ozone can react by a direct reaction (slow and selective) with an organic
compound P:
O 3ðgÞ ! O 3ðlÞ þ P ! P ox k % 1x10
3 1=ðM sÞ
ð 7:6Þ
or by a radical reaction (rapid and non-selective), accelerated in alkaline media
(Huang et al. 1993; Domènech et al. 2004; Litter 2005; Oppenländer 2003; Glaze
124
M. I. Litter