Oxidation of metal–diethylenetriamine-pentaacetate (DTPA) – complexes during drinking water ozonation

Stemmler, Konrad; Glod, Guy; Gunten, Urs von

doi:10.1016/s0043-1354(00)00457-7

Cited by 26 publications

(8 citation statements)

References 10 publications

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“…In a previous study, the degradation of atrazine and the formation of its degradation products could be predicted successfully by measuring the Rct and the rate constants for the oxidation of atrazine and its degradation products with ozone and OH radicals (16). This quantitative kinetic approach, which has also been applied to asses the oxidation of metal-diethylenetriaminepentaacetate (DTPA) complexes during drinking water ozonation (17), will be used to predict the behavior of MTBE and its primary degradation products during ozonation and the AOP O3/H2O2 for various raw waters.…”

Section: Introductionmentioning

confidence: 99%

MTBE Oxidation by Conventional Ozonation and the Combination Ozone/Hydrogen Peroxide: Efficiency of the Processes and Bromate Formation

Acero

Haderlein

Schmidt

et al. 2001

Environ. Sci. Technol.

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155

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The present study investigates the oxidation of methyl tert-butyl ether (MTBE) by conventional ozonation and the advanced oxidation process (AOP) ozone/hydrogen peroxide under drinking water treatment conditions. The major degradation products identified were tert-butyl formate (TBF), tert-butyl alcohol (TBA), 2-methoxy-2-methyl propionaldehyde (MMP), acetone (AC), methyl acetate (MA), hydroxyisobutyraldehyde (HiBA), and formaldehyde (FA). The rate constants of the reaction of ozone and OH radicals with MTBE were found to be 0.14 and 1.9 x 10(9) M(-1) s(-1), respectively. The rate constants for the same oxidation processes were also measured for the degradation products TBF, MMP, MA, and HiBA (k(O3-TBF) = 0.78 M(-1) s(-1); k(OH-TBF) = 7.0 x 10(8) M(-1) s(-1); k(O3-MMP) = 5 M(-1) s(-1); k(OH-MMP) = 3 x 10(9) M(-1) s(-1), k(O3-MA) = 0.09 M(-1) s(-1), k(O3-HiBA) = 5 M(-1) s(-1); k(OH-HiBA) = 3 x 10(9) M(-1) s(-1)). Since all compounds reacted slowly with molecular ozone, only the degradation pathway of MTBE with OH radicals has been determined, including the formation of primary degradation products. In experiments performed with several natural waters, the efficiency of MTBE elimination and the formation of bromate as disinfection byproduct have been measured. With a bromide level of 50 microg/L, only 35-50% of MTBE could be eliminated by the AOP O3/H2O2 without exceeding the current drinking water standard of bromate (10 microg/L). The transient concentrations of MTBE and its primary degradation products were modeled using a combination of kinetic parameters (degradation product distribution and rate constants) together with the ozone and OH radical concentration and were in good agreement with the experimental results.

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Section: Introductionmentioning

confidence: 99%

MTBE Oxidation by Conventional Ozonation and the Combination Ozone/Hydrogen Peroxide: Efficiency of the Processes and Bromate Formation

Acero

Haderlein

Schmidt

et al. 2001

Environ. Sci. Technol.

Self Cite

155

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“…Electrochemical and advanced oxidation methods can be applied to remove aminopolycarboxylates (APC) in water (Quattara et al 2003;Stemmler et al, 2001). These methods though adequate, may have limitations in removing chelates in bulk quantities of materials in water.…”

Section: Iron(vi) Oxidation Of Aminopolycarboxylate Chelating Agentsmentioning

confidence: 99%

Use of Iron(VI) and Iron(V) as Oxidants and Disinfectants in Water Treatment

Sharma¹

2005

proc water environ fed

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A technology involving environmentally friendly oxidants, ferrates (Fe(VI), Fe VI O 4 2-and Fe(V), (Fe V O 4 3-)) can meet criteria of water treatment. Fe(VI) and Fe(V) have high oxidizing power, selectivity, and upon decomposition produce a non-toxic by-product, Fe(III). Fe(VI) is easily be prepared by oxidizing Fe(III) by hypochlorite in alkaline medium. Fe(V) is produced by oneelectron reduction of Fe(VI) using three different methods: chemical (e.g. Fe(II)), electron beam (eaq ), and photocatalytic (conduction band electron).Fe(VI) exhibits a multitude of advantageous properties; these include higher reactivity and selectivity as an oxidant, disinfectant, antifoulant, and coagulant. Examples include treatment of cyanides and toxic metals, and inactivation of microorganisms. Rates of oxidation increase with a decrease in pH and are related to protonation of Fe VI O 4 2-. Oxidation of sulfur-and nitrogencontaining pollutants by Fe(VI) can be accomplished in seconds to minutes with formation of non-hazardous products. Fe(VI) can easily oxidize the amino acid components of microcystins and is a suitable disinfectant for detoxifying toxins in water. Fe(V) is more powerful oxidant than is Fe(VI). The oxidation of pollutants and amino acids with Fe(V) is 3-5 orders of magnitude faster than with Fe(VI). Removal of pollutants by Fe(V) can be completed in microseconds to millisecond time scales. The use of ionizing radiation and photocatalytic techniques in the presence of Fe(VI) results in Fe(V) formation and may have synergistic effects on the oxidation of pollutants and removal of toxins in water. Fe(V) can be useful in inactivation of microbial contaminants that are resistant to chlorination, chloramines, and Fe(VI). This paper gives examples of the multi-functional properties of Fe(VI) and Fe(V) to treat water and wastewater.

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“…The antioxidant α-tocopherol was used to maintain the stability of DTPA penta-ethyl ester. [19] The DTPA penta-ethyl ester has five ester groups, which can be hydrolyzed and oxidized in high relative humidity and temperature environments; [20] thus, our design maximized drug stability and drug loading, and minimized water absorption. In this investigation, the D-optimal mixture design [21, 22] was used to select the optimum formulation.…”

Section: Introductionmentioning

confidence: 99%

Solid dispersions of the penta-ethyl ester prodrug of diethylenetriaminepentaacetic acid (DTPA): formulation design and optimization studies

Pasqua

Zhang

et al. 2013

Pharmaceutical Development and Technology

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The penta-ethyl ester prodrug of diethylenetriaminepentaacetic acid (DTPA), which exists as an oily liquid, was incorporated into a solid dispersion for oral administration by the solvent evaporation method using blends of polyvinylpyrrolidone (PVP), Eudragit® RL PO and α-tocopherol. D-optimal mixture design was used to optimize the formulation. Formulations that had a high concentration of both Eudragit® RL PO and α-tocopherol exhibited low water absorption and enhanced stability of the DTPA prodrug. Physicochemical properties of the optimal formulation were evaluated using Fourier transform infrared (FTIR) spectroscopy and differential scanning calorimetry (DSC). In vitro release of the prodrug was evaluated using the USP Type II apparatus dissolution method. DSC studies indicated that the matrix had an amorphous structure, while FTIR spectrometry showed that DTPA penta-ethyl ester and excipients did not react with each other during formation of the solid dispersion.. Dissolution testing showed that the optimized solid dispersion exhibited a prolonged release profile, which could potentially result in a sustained delivery of DTPA penta-ethyl to enhance bioavailability. In conclusion, DTPA penta-ethyl ester was successfully incorporated into a solid matrix with high drug loading and improved stability compared to prodrug alone.

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Oxidation of metal–diethylenetriamine-pentaacetate (DTPA) – complexes during drinking water ozonation

Cited by 26 publications

References 10 publications

MTBE Oxidation by Conventional Ozonation and the Combination Ozone/Hydrogen Peroxide: Efficiency of the Processes and Bromate Formation

MTBE Oxidation by Conventional Ozonation and the Combination Ozone/Hydrogen Peroxide: Efficiency of the Processes and Bromate Formation

Use of Iron(VI) and Iron(V) as Oxidants and Disinfectants in Water Treatment

Solid dispersions of the penta-ethyl ester prodrug of diethylenetriaminepentaacetic acid (DTPA): formulation design and optimization studies

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