Abstract
Mechanistic aspects of the role of 20 kHz ultrasonication in photocatalytic oxidation of dimethyl methylphosphonate (DMMP), a simulant for nerve chemical warfare agents, were studied in a batch reactor. We found that DMMP did not undergo mineralization under low frequency (20 kHz) ultrasonic irradiation. The increase of the rate of DMMP photocatalytic mineralization in the presence of ultrasound was not due to deagglomeration of TiO2, but was associated with enhanced mass transport of reagents. The same intermediate non-volatile products were detected in photocatalytic and sonophotocatalytic degradation. A kinetic model involving all stable intermediate species detected was introduced. Apparent rate constants of all stages of DMMP mineralization increase under sonication. A reaction route of DMMP mineralization without the formation of intermediate products appeared under ultrasonication. Such behaviour was attributed to enabling mass transport of DMMP into micropores and to the surface of TiO2.
Similar content being viewed by others
References
Y.-C. Yang, Chemical reactions for neutralizing chemical warfare agents, Chem. Ind., 1995, 9, 334–337.
Y.-C. Yang, J. A. Baker and J. R. Ward, Decontamination of chemical warfare agents, Chem. Rev., 1992, 92, 1729–1743.
Z. Hua, Z. Manping, X. Zongfeng, G. K-C. Low, Titanium dioxide mediated photocatalytic degradation of monocrotophos, Water Res., 1995, 29, 2681–2688.
R. Doong and W. Chang, Photoassisted titanium dioxide mediated degradation of organophosphorus pesticides by hydrogen peroxide, J. Photochem. Photobiol. A, 1997, 107, 239–244.
J. M. Herrmann, C. Guillard, M. Arguello, A. Agüera, A. Tejedor, L. Piedra, A. Fernández-Alba, Photocatalytic degradation of pesticide pirimiphos-methyl — Determination of the reaction pathway and identification of intermediate products by various analytical methods, Catal. Today, 1999, 54, 353–367.
R. Doong and W. Chang, Photodegradation of parathion in aqueous titanium dioxide and zero valent iron solutions in the presence of hydrogen peroxide, J. Photochem. Photobiol. A, 1998, 116, 221–228.
M.-C. Lu, G.-D. Roam, J.-N. Chen and C. P. Huang, Photocatalytic mineralization of toxic chemicals with illuminated TiO2, Chem. Eng. Commun., 1995, 139, 1–13.
I. Konstantinou, T. Sakellarides, V. Sakkas and T. Albanis, Photocatalytic degradation of selected s-triazine herbicides and organophosphorus insecticides over aqueous TiO2 suspensions, Environ. Sci. Technol., 2001, 35, 398–405.
C. Pétrier, M.-F. Lamy, A. Francony, A. Benahcene and B. David, Sonochemical degradation of phenol in dilute aqueous-solutions — comparison of the reaction-rates at 20 kHz and 487 kHz, J. Phys. Chem., 1994, 98, 10514–10520.
I. Z. Shirgaonkar and A. B. Pandit, Sonophotochemical destruction of aqueous solution of 2,4,6-trichlorophenol, Ultrason. Sonochem., 1998, 5, 53–61.
V. Ragaini, E. Selli, C. L. Bianchi and C. Pirola, Sono-photocatalytic degradation of 2-chlorophenol in water: kinetic and energetic comparison with other techniques, Ultrason. Sonochem., 2001, 8, 251–258.
J. Peller, O. Wiest and P. V. Kamat, Sonolysis of 2,4-dichlorophenoxyacetic acid in aqueous solutions. Evidence for OH-radical-mediated degradation, J. Phys. Chem. A, 2001, 105, 3176–3181.
P. Théron, P. Pichat, C. Guillard, C. Pétrier and T. Chopin, Degradation of phenyltrifluoromethylketone in water by separate or simultaneous use of TiO2 photocatalysis and 30 or 515 kHz ultrasound, Phys. Chem. Chem. Phys., 1999, 1, 4663–4668.
Y. Jiang, S. Decker, C. Mohs and K. J. Klabunde, Catalytic solid state reactions on the surface of nanoscale metal oxide particles, J. Catal., 1998, 180, 24–35.
S. R. Segal, L. Cao, S. L. Suib, X. Tang and S. Satyapal, Thermal decomposition of dimethyl methylphosphonate over manganese oxide catalysts, J. Catal., 2001, 198, 66–76.
S. P. Decker, J. S. Klabunde, A. Khaleel and K. J. Klabunde, Catalyzed destructive adsorption of environmental toxins with nanocrystalline metal oxides. Fluoro-, chloro-, bromocarbons, sulfur, and organophosophorus compounds, Environ. Sci. Technol., 2002, 36, 762–768.
S. Segal, S. L. Suib, X. Tang and S. Satyapal, Photoassisted decomposition of dimethyl methylphosphonate over amorphous manganese oxide catalysts, Chem. Mater., 1999, 11, 1687–1695.
J. H. Werner and T. A. Cool, Kinetic model for the decomposition of DMMP in a hydrogen/oxygen flame, Combust. Flame, 1999, 117, 78–98.
K. E. O’Shea, S. Beightol, I. Garcia, M. Aguilar, D. V. Kalen and W. J. Cooper, Photocatalytic decomposition of organophosphonates in irradiated TiO2 suspensions, J. Photochem. Photobiol. A, 1997, 107, 221–226.
K. E. O’Shea, I. Garcia and M. Aguilar, TiO2 photocatalytic degradation of dimethyl- and diethyl- methylphosphonate, effects of catalyst and environmental factors, Res. Chem. Intermed., 1997, 23, 325–339.
A. V. Vorontsov, L. Davydov, E. P. Reddy, E. N. Savinov and P. G. Smirniotis, Routes of photocatalytic destruction of chemical warfare agents simulants, New J. Chem., 2002, 26, 732–744.
C. N. Rusu and J. T. Yates, Adsorption and decomposition of dimethyl methylphosphonate on TiO2, J. Phys. Chem. B, 2000, 104, 12292–12298.
C. N. Rusu and J. T. Yates, Photooxidation of dimethyl methylphosphonate on TiO2 powder, J. Phys. Chem. B, 2000, 104, 12299–12305.
T. N. Obee and S. Satyapal, Photocatalytic decomposition of DMMP on titania, J. Photochem. Photobiol. A, 1998, 118, 45–51.
K. E. O’Shea, A. Aguila, K. Vinodgopal and P. V. Kamat, Reaction pathways and kinetics parameters of sonolytically induced oxidation of dimethyl methyl-phosphonate in air saturated aqueous solutions, Res. Chem. Intermed., 1998, 24, 695–705.
D. Drijvers, H. V. Langenhove and K. Vervaet, Sonolysis of chlorobenzene in aqueous solution: organic intermediates, Ultrason. Sonochem., 1998, 5, 13–19.
K. Vinodgopal, J. Peller, O. Makogon and P. V. Kamat, Ultrasonic mineralization of a reactive textile azo dye, Remazol black B, Water Res., 1998, 32, 3646–3650.
J. Schramm and I. Hua, Ultrasonic irradiation of dichlorvos: Decomposition mechanism, Water Res., 2001, 35, 665–674.
L. Davydov, E. P. Reddy, P. France and P. Smirniotis, Sonophotocatalytic destruction of organic contaminants in aqueous systems on TiO2 powders, Appl. Catal. B, 2001, 32, 95–105.
Y. Kado, M. Atobe and T. Nonaka, Ultrasonic effects on electroorganic processes — Part 20. Photocatalytic oxidation of aliphatic alcohols in aqueous suspension of TiO2 powder, Ultrason Sonochem., 2001, 8, 69–74.
S. Matsuzawa, J. Tanaka, S. Sato and T. Ibusuki, Photocatalytic oxidation of dibenzothiophenes in acetonitrile using TiO2: effect of hydrogen peroxide and ultrasound irradiation, J. Photochem. Photobiol. A, 2002, 149, 183–189.
C. S. Turchi and D. F. Ollis, Photocatalytic degradation of organic-water contaminants — mechanisms involving hydroxyl radical attack, J. Catal., 1990, 122, 178–192.
Y. Nosaka, M. Kishimoto and J. Nishino, Factors governing the initial process of TiO2 photocatalysis studied by means of in-situ electron spin resonance measurements, J. Phys. Chem. B, 1998, 102, 10279–10283.
X. Yang and N. Tamai, How fast is interfacial hole transfer? In situ monitoring of carrier dynamics in anatase TiO2 nanoparticles by femtosecond laser spectroscopy, Phys. Chem. Chem. Phys., 2001, 1, 3393–3398.
N. L. Stock, J. Peller, K. Vinodgopal and P. V. Kamat, Combinative sonolysis and photocatalysis for textile dye degradation, Environ. Sci. Technol., 2000, 34, 1747–1750.
A. Aguila, K. E. O’Shea, T. Tobien, K.-D. Asmus, Reactions of hydroxyl radical with dimethyl methylphosphonate and diethyl methylphosphonate. A fundamental mechanistic study, J. Phys. Chem. A, 2001, 105, 7834–7839.
G. V. Buxton, C. L. Greenstock, W. P. Helman and A. B. Ross, Critical-review of rate constants for reactions of hydrated electrons, hydrogen-atoms and hydroxyl radicals in aqueous-solution, J. Phys. Chem. Ref. Data, 1988, 17, 513–817.
K. E. O’Shea, E. Pernas and J. Saiers, The influence of mineralization products on the coagulation of TiO2 photocatalyst, Langmuir, 1999, 15, 2071–2076.
A. V. Vorontsov, A. A. Panchenko, E. N. Savinov, C. Lion and P. G. Smirniotis, Photocatalytic Degradation of 2-phenethyl-2-chloroethylsulfide in Liquid and Gas Phases, Environ. Sci. Technol., 2002, 36, 5261–5269.
A. V. Vorontsov, E. N. Savinov and P. G. Smirniotis, Vibrofluidized- and Fixed-Bed Photocatalytic Reactors: Case of Gaseous Acetone Photooxidation, Chem. Eng. Sci., 2000, 55, 5089–5098.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Chen, YC., Vorontsov, A.V. & Smirniotis, P.G. Enhanced photocatalytic degradation of dimethyl methylphosphonate in the presence of low-frequency ultrasound. Photochem Photobiol Sci 2, 694–698 (2003). https://doi.org/10.1039/b300444a
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1039/b300444a