TY - JOUR
T1 - Mn(II) oxidation in Fenton and Fenton type systems
T2 - Identification of reaction efficiency and reaction products
AU - van Genuchten, Case M.
AU - Peña, Jasquelin
N1 - Publisher Copyright:
© 2017 American Chemical Society.
PY - 2017/3/7
Y1 - 2017/3/7
N2 - Efficient and low-cost methods of removing aqueous Mn(II) are required to improve the quality of impacted groundwater supplies. In this work, we show that Fe(0) electrocoagulation (EC) permits the oxidative removal of Mn(II) from solution by reaction with the reactive oxidant species produced through Fe(II) oxidation. Manganese(II) removal was enhanced when the accumulation of aqueous Fe(II) was minimized, which was achieved at low Fe(II) production rates, high pH, the presence of H2O2 instead of O2 as the initial Fe(II) oxidant, or a combination of all three. In addition, in the EC-H2O2 system, Mn(II) removal efficiency increased as pH decreased from 6.5 to 4.5 and as pH increased from 6.5 to 8.5, which implicates different reactive oxidants in acidic and alkaline solutions. Chemical analyses and X-ray absorption spectroscopy revealed that Mn(II) removal during Fe(0) EC leads to the formation of Mn(III) (0.02 to >0.26 Mn·Fe-1 molar ratios) and its incorporation into the resulting Fe(III) coprecipitates (lepidocrocite and hydrous ferric oxide for EC-O2 and EC-H2O2, respectively), regardless of pH and Fe(II) production rate. The Mn(II) oxidation pathways elucidated in this study set the framework to develop kinetic models on the impact of Mn(II) during EC treatment and in other Fenton type systems.
AB - Efficient and low-cost methods of removing aqueous Mn(II) are required to improve the quality of impacted groundwater supplies. In this work, we show that Fe(0) electrocoagulation (EC) permits the oxidative removal of Mn(II) from solution by reaction with the reactive oxidant species produced through Fe(II) oxidation. Manganese(II) removal was enhanced when the accumulation of aqueous Fe(II) was minimized, which was achieved at low Fe(II) production rates, high pH, the presence of H2O2 instead of O2 as the initial Fe(II) oxidant, or a combination of all three. In addition, in the EC-H2O2 system, Mn(II) removal efficiency increased as pH decreased from 6.5 to 4.5 and as pH increased from 6.5 to 8.5, which implicates different reactive oxidants in acidic and alkaline solutions. Chemical analyses and X-ray absorption spectroscopy revealed that Mn(II) removal during Fe(0) EC leads to the formation of Mn(III) (0.02 to >0.26 Mn·Fe-1 molar ratios) and its incorporation into the resulting Fe(III) coprecipitates (lepidocrocite and hydrous ferric oxide for EC-O2 and EC-H2O2, respectively), regardless of pH and Fe(II) production rate. The Mn(II) oxidation pathways elucidated in this study set the framework to develop kinetic models on the impact of Mn(II) during EC treatment and in other Fenton type systems.
UR - http://www.scopus.com/inward/record.url?scp=85020436873&partnerID=8YFLogxK
U2 - 10.1021/acs.est.6b05584
DO - 10.1021/acs.est.6b05584
M3 - Article
C2 - 28135801
AN - SCOPUS:85020436873
SN - 0013-936X
VL - 51
SP - 2982
EP - 2991
JO - Environmental Science and Technology
JF - Environmental Science and Technology
IS - 5
ER -