TABLE 4.

Theoretical overall energy-generating equations for benzene degradation under methanogenic, sulfate-reducing, iron-reducing, and nitrate-reducing conditions

Electron acceptors (oxidized/reduced)	Overall energetic equation	ΔG°′ (kJ/mol)a
CO2/CH4	C6H6 + 6.75 H2O→2.25 HCO3− + 3.75 CH4 + 2.25 H+	−116
SO42−/H2S	C6H6 + 3 H2O + 3.75 SO42−→6 HCO3− + 1.875 H2S + 1.875 HS− + 0.375 H+	−200
Fe3+/Fe2+	C6H6 + 18 H2O + 30 Fe3+→6 HCO3− + 30 Fe2+ + 36 H+	−3,070
NO3−/N2	C6H6 + 6 NO3−→6 HCO3− + 3 N2	−2,990
NO3−/NO2−	C6H6 + 15 NO3− + 3 H2O→6 HCO3− + 15 NO2− + 6 H	−2,020

^aThe data used to calculate the standard free energy changes (ΔG°′) were obtained from references 14, 18 and 19.