12 Chlorophenols Dechlorination Water Treatment Using …
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accumulation of lower CPs. In general, CPs with a higher degree of chlorination
demonstrated greater CP dechlorination. The reactivity of CPs with Ni/Fe bimetallic system followed the sequence of PCP > 2,3,4,6-TeCP > 2,4,6-TCP ≈ 2,4-DCP
over the 25 days reaction. As the degree of chlorination of the CPs decreased, the
CPs showed an increased affinity for incorporation (sorption, co-precipitation and/or
physical entrapment of CP and/or degradation products) with the iron oxides, incomplete mass recovery of CPs, and decreased dechlorination. In particular, 2,4,6-TCP
and 2,4-DCP demonstrated a greater tendency for incorporation with the iron oxides.
This effect of 2,4,6-TCP and 2,4-DCP may be attributed to the higher pKa values
of these two CPs leading to a greater affinity for incorporation with the oxides thus
lack of availability of these two CPs in the aqueous phase hindering the dechlorination. Furthermore, relatively high amounts of passive oxides (akaganeite, haematite,
lepidocrocite, wustite, goethite, ferrihydrite) along with relatively low amounts of
magnetite (compared to that with PCP and 2,3,4,6-TeCP) was detected during the
reaction of 2,4,6-TCP and 2,4-DCP with Ni/Fe bimetal. The passive oxides seemed
to hinder the dechlorination of 2,4,6-TCP and 2,4-DCP, but possibly increased CPs
incorporation with the oxides.
Acknowledgements Authors would like to thank Dr. Michel Nieuwoudt for the technical assistance provided with the Raman spectroscopic analysis. The research funding was provided by the
New Zealand International Doctoral Research Scholarship, New Zealand Foundation for Research,
Science and Technology and the University of Auckland, New Zealand.
References
Arning MD, Minteer SD (2007) Electrode potentials. In: Handbook of electrochemistry. In: Zoski
CG (ed). Elsevier Science, p 934
ATSDR (Agency for Toxic Substances and Disease Registry) (1999) Toxicological profile for
chlorophenols. Agency for toxic substances and disease registry. U.S Department of Health and
Human Services, p 260
Cheng R, Wang Jl, Zhang W-x (2007) Comparison of reductive dechlorination of p-chlorophenol
using Fe 0 and nanosized Fe 0 . J Hazard Mater 144:334–339
Cheng R, Zhou W, Wang J-L, Qi D, Guo L, Zhang W-X, Qian Y (2010) Dechlorination of pentachlorophenol using nanoscale Fe/Ni particles: Role of nano-Ni and its size effect. J Hazard
Mater 180:79–85
Choi JH, Choi SJ, Kim YH (2008) Hydrodechlorination of 2,4,6-trichlorophenol for a permeable
reactive barrier using zero-valent iron and catalyzed iron. Korean J Chem Eng 25:493–500
Chun CL, Baer DR, Matson DW, Amonette JE, Penn RL (2010) Characterization and reactivity of
iron nanoparticles prepared with added Cu, Pd, and Ni. Environ Sci Technol 44:5079–5085
Cornell RM, Schwertmann U (2003) The iron oxides structure, properties, reactions, occurrences,
and uses. Wiley-VCH, Weinheim, p 659
Cwiertny DM, Bransfield SJ, Roberts AL (2007) Influence of the oxidizing species on the reactivity
of iron-based bimetallic reductants. Environ Sci Technol 41(10):3734–3740
Czaplicka M (2004) Sources and transformations of chlorophenols in the natural environment. Sci
Total Environ 322:21–39
291
accumulation of lower CPs. In general, CPs with a higher degree of chlorination
demonstrated greater CP dechlorination. The reactivity of CPs with Ni/Fe bimetallic system followed the sequence of PCP > 2,3,4,6-TeCP > 2,4,6-TCP ≈ 2,4-DCP
over the 25 days reaction. As the degree of chlorination of the CPs decreased, the
CPs showed an increased affinity for incorporation (sorption, co-precipitation and/or
physical entrapment of CP and/or degradation products) with the iron oxides, incomplete mass recovery of CPs, and decreased dechlorination. In particular, 2,4,6-TCP
and 2,4-DCP demonstrated a greater tendency for incorporation with the iron oxides.
This effect of 2,4,6-TCP and 2,4-DCP may be attributed to the higher pKa values
of these two CPs leading to a greater affinity for incorporation with the oxides thus
lack of availability of these two CPs in the aqueous phase hindering the dechlorination. Furthermore, relatively high amounts of passive oxides (akaganeite, haematite,
lepidocrocite, wustite, goethite, ferrihydrite) along with relatively low amounts of
magnetite (compared to that with PCP and 2,3,4,6-TeCP) was detected during the
reaction of 2,4,6-TCP and 2,4-DCP with Ni/Fe bimetal. The passive oxides seemed
to hinder the dechlorination of 2,4,6-TCP and 2,4-DCP, but possibly increased CPs
incorporation with the oxides.
Acknowledgements Authors would like to thank Dr. Michel Nieuwoudt for the technical assistance provided with the Raman spectroscopic analysis. The research funding was provided by the
New Zealand International Doctoral Research Scholarship, New Zealand Foundation for Research,
Science and Technology and the University of Auckland, New Zealand.
References
Arning MD, Minteer SD (2007) Electrode potentials. In: Handbook of electrochemistry. In: Zoski
CG (ed). Elsevier Science, p 934
ATSDR (Agency for Toxic Substances and Disease Registry) (1999) Toxicological profile for
chlorophenols. Agency for toxic substances and disease registry. U.S Department of Health and
Human Services, p 260
Cheng R, Wang Jl, Zhang W-x (2007) Comparison of reductive dechlorination of p-chlorophenol
using Fe 0 and nanosized Fe 0 . J Hazard Mater 144:334–339
Cheng R, Zhou W, Wang J-L, Qi D, Guo L, Zhang W-X, Qian Y (2010) Dechlorination of pentachlorophenol using nanoscale Fe/Ni particles: Role of nano-Ni and its size effect. J Hazard
Mater 180:79–85
Choi JH, Choi SJ, Kim YH (2008) Hydrodechlorination of 2,4,6-trichlorophenol for a permeable
reactive barrier using zero-valent iron and catalyzed iron. Korean J Chem Eng 25:493–500
Chun CL, Baer DR, Matson DW, Amonette JE, Penn RL (2010) Characterization and reactivity of
iron nanoparticles prepared with added Cu, Pd, and Ni. Environ Sci Technol 44:5079–5085
Cornell RM, Schwertmann U (2003) The iron oxides structure, properties, reactions, occurrences,
and uses. Wiley-VCH, Weinheim, p 659
Cwiertny DM, Bransfield SJ, Roberts AL (2007) Influence of the oxidizing species on the reactivity
of iron-based bimetallic reductants. Environ Sci Technol 41(10):3734–3740
Czaplicka M (2004) Sources and transformations of chlorophenols in the natural environment. Sci
Total Environ 322:21–39