Effect of PH on PCP Remediation by Smectite Supported Pd⁰/Fe⁰

Abstract:

Due to its influence on iron corrosion and involvement in dechlorination reaction, the concentration of H+ (i.e. reaction pH) is crucial to the reactivity and efficiency of nanosized Pd0/Fe0. In this study, PCP dechlorination by smectite-templated Pd0/Fe0 was studied and the effect of pH on PCP dechlorination was investigated in detail. The reaction rate constant is critically dependant on the reaction pH over the range 6.0~10.0. When the pH is 6.0~8.0, the dechlorination rate constant () increases rapidly with decreasing the reaction pH value; the rate change is up to 3.346 folds with decreasing of per pH unit; while it decreases down to 0.3338 when pH is in the range 8.0~10.0. The reductive efficiency of zero-valent iron (ZVI) was further investigated by spiking excess PCP in the reaction system. The maximal reaction efficiency of ZVI for PCP dechlorination attains to 78% when pH is 9.0. The difference between the dechlorination rate and reductive efficiency with respect to reaction pH suggest that ZVI could not be effectively utilized to reduce PCP under acidic condition.

• Periodical: Applied Mechanics and Materials (Volumes 295-298)
• Pages: 1490-1496
• DOI: https://doi.org/10.4028/www.scientific.net/AMM.295-298.1490
• Online since: February 2013
• Authors: Jun Li Han, Han Zhong Jia, Cun Yi Song
• Keywords: Palladized Zero-Valent Iron, Pentachlorophenol, pH, Smectite

References

[1] Agrawal, A, Ferguson, W. J, Gardner, B. O, Christ, J. A, Bandstra, J. Z., Tratnyek, P. G. Effects of carbonate species on the kinetics of dechlorination of 1, 1, 1-trichloroethane by zero-valent iron. Environ. Sci. Technol. Vol. 36(2002).

DOI: 10.1021/es025562s

[2] Cao, J. S., Zhang, W. X. Perchlorate reduction by nanoscale iron particles. J. Nanopart. Res. Vol. (2005)7, p.499—506.

[3] Choi, J. H, Choi, S. J., Kim, Y. H. Hydrodechlorination of 2, 4, 6-trichlorophenol for a permeable reactive barrier using zero-valent iron and catalyzed iron. Korean J. Chem. Eng. Vol. 3 (2008), p.493—500.

DOI: 10.1007/s11814-008-0083-5

[4] Chena, J. L., Al-Abed, R. S., Ryan, A. J., Li, Z. B. Effects of PH on dechlorination of TCE by zero-valent iron. J. Hazard. Mater. Vol. 83( 2001) , p.243–254.

DOI: 10.1016/s0304-3894(01)00193-5

[5] Farrell, J., Kason, M., Melitas, N. Investigation of the long-term performance of zero-valent iron for reductive dechlorination of trichloroethylene. Environ. Sci. Technol. Vol. 34(2000 ), p.514–521.

DOI: 10.1021/es990716y

[6] Gu, C., Jia, H. Z., Li, H., Teppen, J. B., Boyd, A. S. Synthesis of highly reactive subnano-sized zero-valent iron using smectite clay templates, Environ. Sci. Technol. Vol. 11(2010 ), p.4258–4263.

DOI: 10.1021/es903801r

[7] He, F., Zhao, D. Y. Hydrodechlorination of trichloroethene using stabilized Fe-Pd nanoparticles: Reaction mechanism and effects of stabilizers, catalysts and reaction conditions. Appl. Catal. B: Environ. Vol. 84(2008) , p.533–540.

DOI: 10.1016/j.apcatb.2008.05.008

[8] ia, H.Z., Gu, C., Boyd, S.A., Teppen, B.J., Johnston, C.T. Song, C., Li, H. Comparison of Reactivity of Nano-scaled Zero-Valent Iron Formed on Clay Surfaces, Soil Sci. Soc. America. J. Vol. 75(2010) , p.357−364.

DOI: 10.2136/sssaj2010.0080nps

[9] Jiao, Y.L., Qiu, C.C., Huang, L.H., Wu, K., Ma, H., Chen, S.H., Ma, L.M., Wu, D.L. Reductive dechlorination of carbon tetrachloride by zero-valent iron and related iron corrosion. Appl. Catal. B: Environ. Vol. 91( 2009 ), p.434−440.

DOI: 10.1016/j.apcatb.2009.06.012

[10] Klausen, J., Ranke, J., Schwarzenbach, R. P. Influence of solution composition and column aging on the reduction of nitroaromatic compounds by zero-valent iron. Chemosphere. Vol. 44(2001), p.511–517.

DOI: 10.1016/s0045-6535(00)00385-4

[11] Li, X.Q., Zhang, W.X. Zero-valent iron nanoparticles for abatement of environmental pollutants: materials and engineering aspects. Solid State Mater. Sci. Vol. 31 (2006) , p.111–122.

DOI: 10.1080/10408430601057611

[12] Liu, Y. Q., Lowry, V. G. Effect of particle age (Fe0 content) and solution pH on NZVI reactivity: H2 evolution and TCE dechlorination. Environ. Sci. Technol. Vol. 40(2006) , p.6085–6090.

DOI: 10.1021/es060685o.s001

[13] Liu, Y. Q., Majetich, S., Tilton, R., Sholl, D., Lowry, V. G. TCE dechlorination rates, pathways, and efficiency of nanoscale iron particles with different properties. Environ. Sci. Technol. Vol. 39(2005) , p.1338–1345.

DOI: 10.1021/es049195r

[14] Lowry, V. G., Johnson, K. M. Congener-specific dechlorination of dissolved PCBs by microscale and nanoscale zerovalent iron in a water/methanol solution. Environ. Sci. Technol. Vol. 38(2004), p.5208–5216.

DOI: 10.1021/es049835q

[15] Miyazaki, A., Amano, T., Saito, H., Nakano, Y. Acute toxicity of chlorophenols to earthworms using a simple paper contact method and comparison with toxicities to fresh water organisms. Chemosphere. Vol. 47( 2002), p.65–69.

DOI: 10.1016/s0045-6535(01)00286-7

[16] US EPA, 2004. http: /www. epa. gov/safewater.

[17] Wei, J. J., Xu, X. H., Liu, Y., Wang, D. H. Catalytic hydrodechlorination of 2, 4-dichlorophenol over nanoscale Pd/Fe: Reaction pathway and some experimental parameters, Water Res. Vol. 40(2006), p.348–354.

DOI: 10.1016/j.watres.2005.10.017

[18] Zhang, W. X. Nanoscale iron particles for environmental remediation: overview. J. Nanopart. Res. Vol. 5(2003), p.323–332.

[19] Zhang, W. X., Wang, C. B., Lien, H. L. Treatment of chlorinated organic contaminants with nanoscale bimetallic particles. Catal. Today. Vol. 40(1998), p.387–395.

DOI: 10.1016/s0920-5861(98)00067-4