organic pollutants present in the water. In a recent study, CuFeO 2 nanocubes and
nanoplates were tested for the degradation of ofloxacin. This study proved that the
oxidation efficiency of the CuFeO 2 material depended on the facet of oxide material
(Dai et al. 2018). Fe0/CeO 2 with hydrogen peroxide act as Fenton’s reagent to
degrade tetracycline was studied. In this study, hydrogen peroxide alone showed
less than 20% degradation of tetracycline, whereas hydrogen peroxide with
Fe0/CeO 2 showed 91% degradation efficiency. The material showed recyclability
up to five cycles (Zhang et al. 2019). In another study, CaO 2 /Fe(II) system shows
complete degradation of benzene in 10 minutes, whereas CaO 2 /Fe(III) system with
molar ratio of 15:15 took 80 minutes for degradation of benzene. The study also
proved that molar ratio of CaO 2 and Fe influenced the degradation time of benzene
(Xue et al. 2019). Fe-zeolite catalyst was studied for the removal of ibuprofen
(20 mg/L) in water (Adityosulindro et al. 2018). The Fe-zeolite catalyst along with
two times the stoichiometric amount of H 2 O 2 showed 88% degradation of ibuprofen
at natural pH. In a reaction time of 60 minute, H 2 O 2 dosage of 170 mg L
À1 , HNO3modified coal fly ash (HFA) loading of 10.0 g L
À1 , at pH 2.0, and mixing speed of
150 rpm showed 98% removal of p-nitro phenol (Wang et al. 2017).
13.4.4 Electrochemical Methods
Water electrooxidation is an indirect anodic oxidation process. This process is
classified as an electrochemical advanced oxidation process (EAOP), as it leads to
the in situ production of the hydroxyl radical (•OH). In this process boron-doped
diamond electrode is used as the anode. The electrochemical reaction at the anode is
M þ H 2 O ! M • OH
ð
ÞþH
þ
þ e
À
ð13:1Þ
where M represents the anode material and M(•OH) hydroxyl radical adsorbed on
the anode. Pollutants (R) are then oxidized as follows:
M • OH
ð
ÞþR ! M þ RO þ H
þ
þ e
À
ð13:2Þ
Lindane was oxidized by the hydroxyl radical, (•OH), formed due to the oxidation of water on the anode (M) surface (Dominguez et al. 2018). Carbon sponge and
carbon felt cathodic materials showed good degradation when compared with SS
cathode. The anode used was Boron-doped diamond electrode. The lindane degradation reaction at the anode surface is given in the following reaction,
C 6 H 6 Cl 6 þ 12 H 2 O ! 6 CO 2 þ 6 Cl
À
þ 30 H
þ
þ 24 e
À
ð13:3Þ
The decay in lindane concentration during electrolysis was observed as a function
of current density. Lindane conversion varied from 35% to 80% at current density,
510
G. Dheenadayalan and R. Thiruvengadathan
nanoplates were tested for the degradation of ofloxacin. This study proved that the
oxidation efficiency of the CuFeO 2 material depended on the facet of oxide material
(Dai et al. 2018). Fe0/CeO 2 with hydrogen peroxide act as Fenton’s reagent to
degrade tetracycline was studied. In this study, hydrogen peroxide alone showed
less than 20% degradation of tetracycline, whereas hydrogen peroxide with
Fe0/CeO 2 showed 91% degradation efficiency. The material showed recyclability
up to five cycles (Zhang et al. 2019). In another study, CaO 2 /Fe(II) system shows
complete degradation of benzene in 10 minutes, whereas CaO 2 /Fe(III) system with
molar ratio of 15:15 took 80 minutes for degradation of benzene. The study also
proved that molar ratio of CaO 2 and Fe influenced the degradation time of benzene
(Xue et al. 2019). Fe-zeolite catalyst was studied for the removal of ibuprofen
(20 mg/L) in water (Adityosulindro et al. 2018). The Fe-zeolite catalyst along with
two times the stoichiometric amount of H 2 O 2 showed 88% degradation of ibuprofen
at natural pH. In a reaction time of 60 minute, H 2 O 2 dosage of 170 mg L
À1 , HNO3modified coal fly ash (HFA) loading of 10.0 g L
À1 , at pH 2.0, and mixing speed of
150 rpm showed 98% removal of p-nitro phenol (Wang et al. 2017).
13.4.4 Electrochemical Methods
Water electrooxidation is an indirect anodic oxidation process. This process is
classified as an electrochemical advanced oxidation process (EAOP), as it leads to
the in situ production of the hydroxyl radical (•OH). In this process boron-doped
diamond electrode is used as the anode. The electrochemical reaction at the anode is
M þ H 2 O ! M • OH
ð
ÞþH
þ
þ e
À
ð13:1Þ
where M represents the anode material and M(•OH) hydroxyl radical adsorbed on
the anode. Pollutants (R) are then oxidized as follows:
M • OH
ð
ÞþR ! M þ RO þ H
þ
þ e
À
ð13:2Þ
Lindane was oxidized by the hydroxyl radical, (•OH), formed due to the oxidation of water on the anode (M) surface (Dominguez et al. 2018). Carbon sponge and
carbon felt cathodic materials showed good degradation when compared with SS
cathode. The anode used was Boron-doped diamond electrode. The lindane degradation reaction at the anode surface is given in the following reaction,
C 6 H 6 Cl 6 þ 12 H 2 O ! 6 CO 2 þ 6 Cl
À
þ 30 H
þ
þ 24 e
À
ð13:3Þ
The decay in lindane concentration during electrolysis was observed as a function
of current density. Lindane conversion varied from 35% to 80% at current density,
510
G. Dheenadayalan and R. Thiruvengadathan