the reduced Fe
2+ ions are reformed by accepting the electrons formed during the
conversion of chemical oxygen demand to CO 2 in the anode side (Gao et al. 2015).
5.6.2 Novel Bioelectro-Fenton System for Environmental
Remediation
Zhu and Ni first designed the bioelectro-Fenton system in 2009. (Li et al. 2018; Zhu
and Ni 2009) The combination of microbial fuel cell (MFC) set up with Fenton
reaction has the advantage of powering Fenton reaction and lowering the cost of
operation since no external power source is used, production H 2 O 2 within the system
and the formation of Fe
2+ ions simultaneously from Fe electrodes. Moreover, instead
of the using sewage sludge as anolyte, marine sediments are used which significantly
improved the power efficiency of MFC (Dios et al. 2014a; Dios et al. 2014b). In
simple words, the essential characteristics that a cathodic material should inherit for
a bioelectroFenton cell are good conductivity, Fe
2+ source, 2e oxygen reduction
catalyst and are resistant to various pH values. (Li et al. 2018).
While associating Fenton system with microbial fuel cell (MFC), the efficiency of
the overall cell can be improved through (1) enhancing the current generation from
MFC and (2) choosing the appropriate electrode material for cathode reaction.
Distinct cathodic electrode materials have been used for enhancing the efficiency
of Fenton processes. For example, Feng and his group used (CNT)/γ-FeOOH for the
degradation of an azo dye Orange II at neutral pH. Here CNT highly favours the
two-electron oxygen reduction reaction whereas γ-FeOOH acts as the Fe
2+ source.
(Feng et al. 2010) Xu et al. used FeVO 4 /CF cathode for the treatment of coal
gasification wastewater. Here both Fe
3+ and V
5+ will act as a catalyst for the
production of OH• radicals which has considerably increased the overall efficiency
for the removal of pollutant. (Xu et al. 2018) Le et al. used carbon Felt@Au
(CF@Au) and porous carbon deposited CF as the cathode materials. Here ferrous
sulphate solution is taken as catholyte which provides the Fe
2+ source for carrying
out Fenton reaction. (Huongle et al. 2016) Zhuang et al. used Fe@Fe 2 O 3 /carbon felt
for the controlled release of Fenton’s reagent and has used expanded
polytetrafluoroethylene laminated cloth as separator. The separator enhanced the
efficiency of MFC by four times. The proposed mechanism is shown in Fig. 5.3
(Zhuang et al. 2010) Dios and group used iron-containing zeolite for the degradation
of Black 5 dye and phenanthrene. The dye was decolourized nearer to completion
after 90 min, and 78% of phenanthrene degradation was obtained after 30 h. Since
zeolite is a naturally existing adsorbent iron can be easily loaded on the highly
surfaced zeolites. Furthermore, preliminary reusability tests of the developed catalyst showed high degradation levels for successive cycles (Dios et al. 2014a; Dios
et al. 2014b).
In general, the factors that affect the working of bioelectroFenton system are pH,
temperature, the substrate used and the nature of the biocatalyst. (Kahoush et al.
5 Removal of Priority Water Pollutants Using Adsorption and Oxidation. . .
137
2+ ions are reformed by accepting the electrons formed during the
conversion of chemical oxygen demand to CO 2 in the anode side (Gao et al. 2015).
5.6.2 Novel Bioelectro-Fenton System for Environmental
Remediation
Zhu and Ni first designed the bioelectro-Fenton system in 2009. (Li et al. 2018; Zhu
and Ni 2009) The combination of microbial fuel cell (MFC) set up with Fenton
reaction has the advantage of powering Fenton reaction and lowering the cost of
operation since no external power source is used, production H 2 O 2 within the system
and the formation of Fe
2+ ions simultaneously from Fe electrodes. Moreover, instead
of the using sewage sludge as anolyte, marine sediments are used which significantly
improved the power efficiency of MFC (Dios et al. 2014a; Dios et al. 2014b). In
simple words, the essential characteristics that a cathodic material should inherit for
a bioelectroFenton cell are good conductivity, Fe
2+ source, 2e oxygen reduction
catalyst and are resistant to various pH values. (Li et al. 2018).
While associating Fenton system with microbial fuel cell (MFC), the efficiency of
the overall cell can be improved through (1) enhancing the current generation from
MFC and (2) choosing the appropriate electrode material for cathode reaction.
Distinct cathodic electrode materials have been used for enhancing the efficiency
of Fenton processes. For example, Feng and his group used (CNT)/γ-FeOOH for the
degradation of an azo dye Orange II at neutral pH. Here CNT highly favours the
two-electron oxygen reduction reaction whereas γ-FeOOH acts as the Fe
2+ source.
(Feng et al. 2010) Xu et al. used FeVO 4 /CF cathode for the treatment of coal
gasification wastewater. Here both Fe
3+ and V
5+ will act as a catalyst for the
production of OH• radicals which has considerably increased the overall efficiency
for the removal of pollutant. (Xu et al. 2018) Le et al. used carbon Felt@Au
(CF@Au) and porous carbon deposited CF as the cathode materials. Here ferrous
sulphate solution is taken as catholyte which provides the Fe
2+ source for carrying
out Fenton reaction. (Huongle et al. 2016) Zhuang et al. used Fe@Fe 2 O 3 /carbon felt
for the controlled release of Fenton’s reagent and has used expanded
polytetrafluoroethylene laminated cloth as separator. The separator enhanced the
efficiency of MFC by four times. The proposed mechanism is shown in Fig. 5.3
(Zhuang et al. 2010) Dios and group used iron-containing zeolite for the degradation
of Black 5 dye and phenanthrene. The dye was decolourized nearer to completion
after 90 min, and 78% of phenanthrene degradation was obtained after 30 h. Since
zeolite is a naturally existing adsorbent iron can be easily loaded on the highly
surfaced zeolites. Furthermore, preliminary reusability tests of the developed catalyst showed high degradation levels for successive cycles (Dios et al. 2014a; Dios
et al. 2014b).
In general, the factors that affect the working of bioelectroFenton system are pH,
temperature, the substrate used and the nature of the biocatalyst. (Kahoush et al.
5 Removal of Priority Water Pollutants Using Adsorption and Oxidation. . .
137