Enhanced Fenton's destruction of non-aqueous phase perchloroethylene in soil systems

The Fenton's system is applied to the destruction of perchloroethylene (PCE) present as a dense non-aqueous phase liquid (DNAPL) in soil slurry systems; the initial concentration of PCE was 45 times higher than its aqueous solubility. Studies were conducted in two matrices: Ottawa sand and soil from Warsaw, IN. In Ottawa sand, a 60-62% decrease in PCE concentration was observed, and Cl(-) recovery was 47-58%, whereas in Warsaw soil, a 44-49% decrease in PCE concentration and a Cl(-) recovery of 40-42% were observed after the addition of 600 mM H(2)O(2) and 10 mM dissolved iron. Significantly enhanced destruction resulted during application of N-(2-hydroxyethyl) iminodiacetic acid (HEIDA) to Warsaw soil. For example, in the absence of HEIDA in Warsaw soil, 36% PCE loss and 33% Cl(-) release were observed at 600 mM H(2)O(2) and 5 mM Fe(III), while 74% PCE loss and 63% Cl(-) release were achieved at 600 mM H(2)O(2) and 5 mM Fe(III)-HEIDA. For both soils, the catalytic activities of Fe(II) and Fe(III) were nearly equivalent. These findings clearly demonstrate that system design can be optimized with regard to process variables in Fenton's treatment of DNAPL in soils.     

Influence of complex reagents on removal of chromium(VI) by zero-valent iron

The removal of Cr(VI) by zero-valent iron (Fe(0)) and the effect of three complex reagents, ethylenediaminetetraacetic acid (EDTA), NaF and 1,10-phenanthroline, on this reaction were investigated using batch reactors at pH values of 4, 5 and 6. The results indicate that the removal of Cr(VI) by Fe(0) is slow at pH 5.0 and that three complex reagents play different roles in the reaction. EDTA and NaF significantly enhance the reaction rate. The zero-order rate constants at pH 5.0 were 5.44 microM min(-1) in the presence of 4mM EDTA and 0.99 micrM min(-1) in the presence of 8 mM NaF, respectively, whereas that of control was only 0.33 micrM min(-1), even at pH=4.0. This enhancement is attributed to the formation of complex compounds between EDTA/NaF and reaction products, such as Cr(III) and Fe(III), which eliminate the precipitates of Cr(III), Fe(III) hydroxides and Cr(x)Fe(1-)(x)(OH)(3) and thus reduce surface passivation of Fe(0). In contrast, 1,10-phenanthroline, a complex reagent for Fe(II), dramatically decreases Cr(VI) reduction by Fe(0). At pH=4.0, the zero-order rate constant in the presence of 1mM of 1,10-phenanthroline was 0.02 micrM min(-1), decreasing by 99.7% and 93.9%, respectively, compared with the results in the presence and absence of EDTA. The results suggest that a pathway of the reduction of Cr(VI) to Cr(III) by Fe(0) may involve dissolution of Fe(0) to produce Fe(II), followed by reduction of Cr(VI) by Fe(II), rather than the direct reaction between Cr(VI) and Fe(0), in which Fe(0) transfers electrons to Cr(VI).     

Acceleration of the Fe(III)EDTA(-) reduction rate in BioDeNO(x) reactors by dosing electron mediating compounds

BioDeNO(x), a novel technique to remove NO(x) from industrial flue gases, is based on absorption of gaseous nitric oxide into an aqueous Fe(II)EDTA(2-) solution, followed by the biological reduction of Fe(II)EDTA(2-) complexed NO to N(2). Besides NO reduction, high rate biological Fe(III)EDTA(-) reduction is a crucial factor for a succesful application of the BioDeNO(x) technology, as it determines the Fe(II)EDTA(2-) concentration in the scrubber liquor and thus the efficiency of NO removal from the gas phase. This paper investigates the mechanism and kinetics of biological Fe(III)EDTA(-) reduction by unadapted anaerobic methanogenic sludge and BioDeNO(x) reactor mixed liquor. The influence of different electron donors, electron mediating compounds and CaSO(3) on the Fe(III)EDTA(-) reduction rate was determined in batch experiments (21mM Fe(III)EDTA(-), 55 degrees C, pH 7.2+/-0.2). The Fe(III)EDTA(-) reduction rate depended on the type of electron donor, the highest rate (13.9mMh(-1)) was observed with glucose, followed by ethanol, acetate and hydrogen. Fe(III)EDTA(-) reduction occurred at a relatively slow (4.1mMh(-1)) rate with methanol as the electron donor. Small amounts (0.5mM) of sulfide, cysteine or elemental sulfur accelerated the Fe(III)EDTA(-) reduction. The amount of iron reduced significantly exceeded the amount that can be formed by the chemical reaction of sulfide with Fe(III)EDTA(-), suggesting that the Fe(III)EDTA(-) reduction was accelerated via an auto-catalytic process with an unidentified electron mediating compound, presumably polysulfides, formed out of the sulfur additives. Using ethanol as electron donor, the specific Fe(III)EDTA(-) reduction rate was linearly related to the amount of sulfide supplied. CaSO(3) (0.5-100mM) inhibited Fe(III)EDTA(-) reduction, probably because SO(3)(2-) scavenged the electron mediating compound.     

Kinetics of oxidation of chlorobenzenes and phenyl-ureas by Fe(II)/H2O2 and Fe(III)/H2O2. Evidence of reduction and oxidation reactions of intermediates by Fe(II) or Fe(III)

The rates of degradation of 1,2,4-trichlorobenzene (TCB), 2,5-dichloronitrobenzene (DCNB), diuron and isoproturon by Fe(II)/H2O2 and Fe(III)/H2O2 have been investigated in dilute aqueous solution ([Organic compound]0 approximately 1 microM, at 25.0 +/- 0.2 degrees C and pH < or = 3). Using the relative rate method with atrazine as the reference compound, and the Fe(II)/H2O2 (with an excess of Fe(II)) and Fe(III)/H2O2 systems as sources of OH radicals, the rate constants for the reaction of OH* with TCB and DCNB were determined as (6.0 +/- 0.3)10(9) and (1.1 +/- 0.2)10(9) M(-1) s(-1). Relative rates of degradation of diuron and isoproturon by Fe(II)/H2O2 were about two times smaller in the absence of dissolved oxygen than in the presence of oxygen. These data indicate that radical intermediates are reduced back to the parent compound by Fe(II) in the absence of oxygen. Oxidation experiments with Fe(III)/H2O2 showed that the rate of decomposition of atrazine markedly increased in the presence of TCB and this increase has been attributed to a regeneration of Fe(II) by oxidation reactions of intermediates (radical species and dihydroxybenzenes) by Fe(III).     

Light-induced disappearance of nitrite in the presence of iron (III)

Understanding of rapid disappearance of nitrite in natural waters and its impact on nitrogen natural cycling has remained limited. We found that NO2- disappeared rapidly in pH 3.2 aqueous Fe(III) solutions both in sunlight and in 356 nm light. Quantum yields of the NO2- loss at 356 nm were 0.049-0.14 for initial levels of 10-80 microns NO2- and 200 microns Fe(III). The NO2- loss (at 356 nm) followed apparent first-order kinetics. The rate constants were 1.3 x 10(-3) (40 microns NO2-) and 4.1 x 10(-4) s-1 (80 microns NO2-) for 100 microns Fe(III), and 2.3 x 10(-3) (40 microns NO2-) and 7.5 x 10(-4) s-1 (80 microns NO2(-1)) for 200 microns Fe(III) (t1/2 = 8.7, 27.9, 5.1, and 15.3 min, respectively). The rate constants were directly proportional to [Fe(III)]0 and inversely proportional to [NO2-]0. Agreement between the rate constants obtained experimentally and those calculated mechanistically supports the hypothesis that NO2- was oxidized to NO2 by .OH radicals from photolysis of FeOH2+ complexes, and at high [NO2-]0 (e.g., 80 microns) relative to [Fe(III)]0, hydrolysis of NO2 or N2O4 to form NO3- and NO2- could be significant. This study showed that light and Fe(III)-induced oxidation of NO2- (rate = approximately 10(-1)-10(-2) microns s-1) was more rapid than its direct photolysis (rate = approximately 10(-4) microns s-1), and the photolysis could be a significant source of .OH radicals only in cases where the Fe(III) level is much lower than the NO2- level ([Fe(III)]/[NO2-] < 1/80). This study suggests that the light and Fe(III)-induced oxidation of NO2- would be one potential important pathway responsible for the rapid transformation of NO2- in acidic surface waters, especially those affected by acid-mine drainage or volcanic activities. This study also may be of interest for modeling certain acidic atmospheric water environments.     

A comparative study of the effects of chloride, sulfate and nitrate ions on the rates of decomposition of H2O2 and organic compounds by Fe(II)/H2O2 and Fe(III)/H2O2

The effects of chloride, nitrate, perchlorate and sulfate ions on the rates of the decomposition of hydrogen peroxide and the oxidation of organic compounds by the Fenton's process have been investigated. Experiments were conducted in a batch reactor, in the dark at pH < or = 3.0 and at 25 degrees C. Data obtained from Fe(II)/H2O2 experiments with [Fe(II)]0/[H2O2]0 > or = 2 mol mol(-1), showed that the rates of reaction between Fe(II) and H2O2 followed the order SO4(2-) > ClO4(-) = NO3- = Cl-. For the Fe(III)/H2O2 process, identical rates were obtained in the presence of nitrate and perchlorate, whereas the presence of sulfate or chloride markedly decreased the rates of decomposition of H2O2 by Fe(III) and the rates of oxidation of atrazine ([atrazine]0 = 0.83 microM), 4-nitrophenol ([4-NP]0 = 1 mM) and acetic acid ([acetic acid]0 = 2 mM). These inhibitory effects have been attributed to a decrease of the rate of generation of hydroxyl radicals resulting from the formation of Fe(III) complexes and the formation of less reactive (SO4(*-)) or much less reactive (Cl2(*-)) inorganic radicals.     

A comparative study of the removal of 3-indolebutyric acid using advanced oxidation processes

In this study, advanced oxidation technologies, namely Fenton Process (FP), Fenton-Like Process (FLP), ozonation (O3) and O3/H2O2 processes, were applied to synthetic wastewater containing 3-indolebutyric acid (IBA). The effectiveness of each process was investigated at different pH values, Fe(+2), Fe(+3), O3 and H2O2 concentrations with respect to the removal efficiencies for chemical oxygen demand (COD) and total organic carbon (TOC). The best removal efficiencies were seen at pH 3 and 2 mM Fe concentration in both FP and FLP, in which the optimum H2O2 concentrations were 6 mM for FP and 10 mM for FLP. Optimum process conditions were pH 12 for the O3 process, pH 9 for the O3/H2O2 process and 1:1 O3/H2O2 molar ratio. The highest COD removal efficiency was 86 percent, obtained in the O3/H2O2 process and the highest TOC removal efficiency was obtained at 77 percent in the FP.     

Oxidation of MCPA and 2,4-D by UV radiation, ozone, and the combinations UV/H2O2 and O3/H2O2

The phenoxyalkyl acid derivative herbicides MCPA (4-chloro 2-methylphenoxyacetic acid) and 2,4-D (2,4-dichlorophenoxyacetic acid) were oxidized in ultrapure water by means of a monochromatic UV irradiation and by ozone, as well as by the combinations UV/H2O2 and O3/H2O2. In the direct photolysis of MCPA, the quantum yield at 20 degrees C was directly evaluated and a value of 0.150 mol Eins(-1) was obtained in the pH range 5-9, while a lower value of 0.41 x 10(-2) mol Eins(-1) was determined at pH=3. Similarly, for 2,4-D a value of 0.81 x 10(-2) mol Eins(-1) was deduced, independent of the pH of work. The influence of the additional presence of hydrogen peroxide was established in the combined process UV/H2O2, and the specific contribution of the radical pathway to the global photo-degradation was evaluated. The oxidation by ozone and by the combination O3/H2O2 was also studied, with the determination of the rate constants for the reactions of both herbicides with ozone and hydroxyl radicals at 20 degrees C. These rate constants for the direct reactions with ozone were 47.7 and 21.9 M(-1) s(-1) for MCPA and 2,4-D respectively, while the found values for the rate constants corresponding to the radical reactions were 6.6 x 10(9) and 5.1 x 10(9) M(-1) s(-1).     

铁炭微电解-H2O2法降解二甲基甲酰胺废水

采用铁炭微电解-H2O2法降解二甲基甲酰胺(DMF)废水,探讨了反应时间、pH、铁炭质量比(简写为Fe/C)以及H2O2投加量对DMF去除率的影响.结果表明:(1)当反应时间为60 min、pH为3、Fe/C为3:1时,DMF去除率为73.4％.(2)向反应体系中投加H2O2,DMF去除率明显提高.当H2O2投放量为0.20 mL/L时,DMF去除率达到95.2％.     

Temperature dependence of hydroxyl radical formation in the hv/Fe3+/H2O2 and Fe3+/H2O2 systems

The thermal enhancement of the formation of *OH by the hv/Fe(III)/H2O2 system (including the Fe(III)/H2O2 system) was quantitatively investigated with reaction temperatures ranging from 25 to 50 degrees C. A temperature dependent kinetic model for the hv/Fe(III)/H2O2 system, incorporating 12 major reactions with no fitted rate constants or activation energies, was developed, and successfully explained the experimental measurements. Particularly, the thermal enhancement of Fe(OH)2+ photolysis which is the most significant step in the hv/Fe(III)/H2O2 system was effectively explained by two factors; (1) the variation of the Fe(OH)2+ concentration with temperature, and (2) the temperature dependence of the quantum yield for Fe(OH)2+ photolysis (measured activation energy=11.4 kJ mol(-1)). Although in both the hv/Fe(III)/H2O2 and Fe(III)/H2O2 systems, elevated temperatures enhanced the formation of *OH, the thermal enhancement was much higher in the dark Fe(III)/H2O2 system than the hv/Fe(III)/H2O2 system. Furthermore, it was found that the relative thermal enhancement of the formation of *OH in the presence of *OH scavengers (tert-butyl alcohol) was magnified in the Fe(III)/H2O2 system but was not in the hv/Fe(III)/H2O2 system.     

Photocatalytic removal of fenitrothion in pure and natural waters by photo-Fenton reaction

The photocatalytic removal kinetics of fenitrothion at a concentration of 0.5mgl(-1) in pure and natural waters were investigated in Fe(III)/H2O2/UV-Vis, Fe(III)/UV-Vis and H2O2/UV-Vis oxidation systems, with respect to decreases in fenitrothion concentrations with irradiation time using a solar simulator. Fenitrothion concentrations were determined by HPLC analysis. Furthermore, total mineralization of fenitrothion in these systems was evaluated by monitoring the decreases in DOC concentrations with solar simulator irradiation time by TOC analysis. It was shown that the degradation rate of fenitrothion was much faster in the Fe(III)/H2O2/UV-Vis system than the Fe(III)/UV-Vis and H2O2/UV-Vis systems in both pure and river waters. Consequently, the mineralization rate of fenitrothion was much faster in the Fe(III)/H2O2/UV-Vis system than in the other two systems. The high *OH generation rate measured in the Fe(III)/H2O2/UV-Vis system was the key to faster degradation of fenitrothion. Increases in the concentrations of H2O2 and Fe led to better final degradation of fenitrothion. These results suggest that the photo-Fenton reaction (Fe(III)/H2O2/UV-Vis) system is likely to be an effective method for removing fenitrothion from contaminated natural waters.     

Remediation of DDT-contaminated water and soil by using pretreated iron byproducts from the automotive industry

The objective of this study was to quantify the effectiveness of different pretreated iron byproducts from the automotive industry to degrade DDT [(1,1,1-trichloro-2,2-bis(4-chlorophenyl) ethane] in aqueous solutions and soil slurry. Iron byproducts from automotive manufacturing were pretreated by three different methods (heating, solvent and 0.5N HCl acid washing) prior to experimentation. All pretreated irons were used at 5% (wt v-1) to treat 0.014 mM (5 mgL-1) of DDT in aqueous solution. Among the pretreated irons, acid pretreated iron results in the fastest destruction rates, with a pseudo first-order degradation rate of 0.364 d-1. By lowering the pH of the DDT aqueous solution from 9 to 3, destruction kinetic rates increase more than 20%. In addition, when DDT-contaminated soil slurry (3.54 mg kg-1) was incubated with 5% (wt v-1) acid-pretreated iron, more than 90% destruction of DDT was observed within 8 weeks. Moreover, DDT destruction kinetics were enhanced when Fe(II), Fe(III) or Al(III) sulfate salts were added to the soil slurry, with the following order of destruction kinetics: Al(III) sulfate > Fe(III) sulfate > Fe(II) sulfate. These results provide proof-of concept that inexpensive iron byproducts of the automotive industry can be used to remediate DDT-contaminated water and soil.     

Investigation of gas production and entrapment in granular iron medium

A method for measuring gas entrapment in granular iron (Fe0) was developed and used to estimate the impact of gas production on porosity loss during the treatment of a high NO3- groundwater (up to approximately 10 mM). Over the 400-d study period the trapped gas in laboratory columns was small, with a maximum measured at 1.3% pore volume. Low levels of dissolved H2(g) were measured (up to 0.07+/-0.02 M). Free moving gas bubbles were not observed. Thus, porosity loss, which was determined by tracer tests to be 25-30%, is not accounted for by residual gas trapped in the iron. The removal of aqueous species (i.e., NO3-, Ca, and carbonate alkalinity) indicates that mineral precipitation contributed more significantly to porosity loss than did the trapped gases. Using the stoichiometric reactions between Fe0 and NO3-, an average corrosion rate of 1.7 mmol kg-1 d-1 was derived for the test granular iron. This rate is 10 times greater than Fe0 oxidation by H2O alone, based on H2 gas production. NO3- ion rather than H2O was the major oxidant in the groundwater in the absence of molecular O2. The N-mass balance [e.g., N2g and NH4+ and NO3-] suggests that abiotic reduction of NO3- dominated at the start of Fe0 treatment, whereas N2 production became more important once the microbial activity began. These laboratory results closely predict N2 gas production in a separated large column experiment that was operated for approximately 2 yr in the field, where a maximum of approximately 600 ml d-1 gas volumes was detected, of which 99.5% (v/v) was N2. We conclude that NO3- suppressed the production of H2(g) by competing with water for Fe0 oxidation, especially at the beginning of water treatment when Fe0 is highly reactive. Depends on the groundwater composition, gas venting may be necessary in maintaining PRB performance in the field.     

Remediation of DDT-Contaminated Water and Soil by Using Pretreated Iron Byproducts from the Automotive Industry

The objective of this study was to quantify the effectiveness of different pretreated iron byproducts from the automotive industry to degrade DDT [(1,1,1-trichloro-2,2-bis(4-chlorophenyl) ethane] in aqueous solutions and soil slurry. Iron byproducts from automotive manufacturing were pretreated by three different methods (heating, solvent and 0.5N HCl acid washing) prior to experimentation. All pretreated irons were used at 5% (wt v^{? 1}) to treat 0.014 mM (5 mgL^{? 1}) of DDT in aqueous solution. Among the pretreated irons, acid pretreated iron results in the fastest destruction rates, with a pseudo first-order degradation rate of 0.364 d^{? 1}. By lowering the pH of the DDT aqueous solution from 9 to 3, destruction kinetic rates increase more than 20%. In addition, when DDT-contaminated soil slurry (3.54 mg kg^{? 1}) was incubated with 5% (wt v^{? 1}) acid-pretreated iron, more than 90% destruction of DDT was observed within 8 weeks. Moreover, DDT destruction kinetics were enhanced when Fe(II), Fe(III) or Al(III) sulfate salts were added to the soil slurry, with the following order of destruction kinetics: Al(III) sulfate > Fe(III) sulfate > Fe(II) sulfate. These results provide proof-of concept that inexpensive iron byproducts of the automotive industry can be used to remediate DDT-contaminated water and soil.     

Effect of Fe (III) on acid degradation of methylparathion

A study was undertaken to determine the transformation kinetic of methylparathion (O, O, -dimethyl O-4 nitrophenylphosphorotioate) in the presence of Fe(III) between pH 2 and 7. The Fe(III) was not electroactive under the conditions used in this study, and polarographic signals were exhibited by methylparathion and main degradation product only. Data suggest that hydrolysis of methylparathion in an acid medium is catalyzed by Fe(III) and the pesticide did not degrade in this medium without this cation. Methylparathion degradation was observed at all the pHs studied and was independent of the predominant chemical form of Fe(III) in the aqueous medium. The reaction was first-order with pH-dependent rate constant (k) values ranging from 3.3 x 10(- 3) h(- 1) to 7.0 x 10(- 3) h(- 1). The k values increased as pH decreased, suggesting that Fe(III) acted as an electrophile in the reaction mechanism.     

Hydrogen peroxide-assisted UV photodegradation of Lindane

Aqueous solutions of gamma-hexachlorocyclohexane (Lindane) were photolyzed (lambda=254 nm) under a variety of solution conditions. The initial concentrations of hydrogen peroxide (H(2)O(2)) and Lindane varied from 0 to 20 mM and 0.21 to 0.22 microM, respectively, the pH ranged from 3 to 11, and several concentration ratios of Suwannee River humic acid and fulvic acid were dissolved in the irradiated solutions. Lindane rapidly reacted, and the maximum reaction rate constant (9.7 x 10(-3) s(-1)) was observed at pH 7 and initial [H(2)O(2)]=1 mM. Thus, 90% of the Lindane is destroyed in approximately 4 min under these conditions. In addition, within 15 min, all chlorine atoms were converted to chloride ion, indicating that chlorinated organic by-products do not accumulate. The reactor was characterized by measuring the photon flux (7.04 x 10(-6) E s(-1)) and the cumulative production of *OH during irradiation. The cumulative *OH production during irradiation was fastest at an initial [H(2)O(2)]=5 mM (k=0.77 micro M s(-1)).     

Remediating dicamba-contaminated water with zerovalent iron

Dicamba (3,6-dichloro-2-methoxybenzoicacid) is a highly mobile pre- and post-emergence herbicide that has been detected in ground water. We determined the potential of zerovalent iron (Fe0) to remediate water contaminated with dicamba and its common biological degradation product, 3,6-dichlorosalicylic acid (DCSA). Mixing an aqueous solution of 100 microM dicamba with 1.5% Fe0 (w/v) resulted in 80% loss of dicamba within 12 h. Solvent extraction of the Fe0 revealed that dicamba removal was primarily through adsorption; however when the Fe0 was augmented with Al or Fe(III) salts, dicamba was dechlorinated to an unidentified degradation product. In contrast to dicamba, Fe0 treatment of DCSA resulted in removal with some dechlorination observed. When DCSA was treated with Fe0 plus Al or Fe(III) salts, destruction was 100%. Extracts of this Fe0 treatment contained the same HPLC degradation peak observed with the Fe0 + Al or Fe(III) salt treatment of dicamba. Molecular modeling suggests that differences in removal and dechlorination rates between dicamba and DCSA may be related to the type of coordination complex formed on the iron surface. Experiments with 14C-labeled dicamba confirmed that Fe-adsorbed dicamba residues are available for subsequent biological mineralization (11% after 125 d). These results indicate that Fe0 could be potentially used to treat dicamba and DCSA-contaminated water.     

Homogeneous degradation of 1,2,9,10-tetrachlorodecane in aqueous solutions using hydrogen peroxide, iron and UV light

The homogeneous degradation of the polychlorinated n-alkane, 1,2,9,10-tetrachlorodecane (T4C10), was studied in aqueous solutions of hydrogen peroxide, including Fenton and photo-Fenton reaction conditions. All solutions were adjusted to a pH of 2.8 and an ionic strength of 0.1 M NaClO4 prior to photolysis. T4C10 (2 x 10(-6) M) was substantially degraded by the H2O2/UV system (1.0 x 10(-2) M H2O2), with 60% disappearance in 20 min of irradiation in a photoreactor equipped with 300 nm lamps of light intensity 3.6 x 10(-5) Ein L(-1) min(-1) (established by ferrioxalate actinometry). The reaction produced stoichiometric amounts of chloride ion indicating complete dechlorination of the chlorinated n-alkane. T4C10 degraded very slowly under Fenton (Fe2+/H2O2/dark) and Fenton-like (Fe3+/H2O2/dark) conditions. However, when the same solutions were irradiated, T4C10 degraded more rapidly than in the H2O2/UV system, with 61% disappearance in 10 min of exposure. The rapid degradation is related to the enhanced degradation of hydrogen peroxide to oxidizing *OH radicals under photo-Fenton conditions. Degradation was inhibited in both the H2O2/UV and photo-Fenton systems by the addition of KI and tert-butyl alcohol due to *OH scavenging.     

Photo-fenton assisted reaction of dimethoate in aqueous solutions

The photo-Fenton reaction of an organophosphorus insecticide, dimethoate (O,O-dimethyl methylcarbamoylmethyl phosphorodithioate), was studied by following the identification and determination of the decomposition products and the total carbon removal rate. The reactions were performed in a batch recycle reactor, at room temperature, using UV radiation, H2O2 as oxidant, and FeCl3 x 6H2O as catalyst. The oxidation results were determined with a total organic carbon (TOC) analyzer and ion chromatography. The presence of reaction products was identified by gas chromatography-mass spectrometry (GC-MS). Apart from the sulfate, phosphate, and ammonium ions, the presence of dimethyl phosphite, N-methyl-acetamide, and formic acid was also detected. Excess of H2O2 concentration did not influence the reaction rate. The expression for the total carbon removal was assessed and the TOC removal rate constants were calculated.