Photometric method for the determination of low concentrations of hydrogen peroxide by the peroxidase catalyzed oxidation of N,N-diethyl-p-phenylenediamine (DPD)
TL;DR: In this paper, the concentration of hydrogen peroxide (H2O2) in distilled water, drinking water and in different types of surface and rain waters can be easily determined by a photometric method in which N,N-diethyl-p-phenylenediamine (DPD) is oxidized by a peroxidase catalyzed reaction.
About: This article is published in Water Research.The article was published on 1988-09-01. It has received 819 citations till now. The article focuses on the topics: Distilled water & Hydrogen peroxide.
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TL;DR: The detection methods and generation mechanisms of the intrinsic reactive oxygen species (ROS) in photocatalysis were surveyed comprehensively and the major photocatalyst used in heterogeneous photocatalytic systems was found to be TiO2.
Abstract: The detection methods and generation mechanisms of the intrinsic reactive oxygen species (ROS), i.e., superoxide anion radical (•O2–), hydrogen peroxide (H2O2), singlet oxygen (1O2), and hydroxyl radical (•OH) in photocatalysis, were surveyed comprehensively. Consequently, the major photocatalyst used in heterogeneous photocatalytic systems was found to be TiO2. However, besides TiO2 some representative photocatalysts were also involved in the discussion. Among the various issues we focused on the detection methods and generation reactions of ROS in the aqueous suspensions of photocatalysts. On the careful account of the experimental results presented so far, we proposed the following apprehension: adsorbed •OH could be regarded as trapped holes, which are involved in a rapid adsorption–desorption equilibrium at the TiO2–solution interface. Because the equilibrium shifts to the adsorption side, trapped holes must be actually the dominant oxidation species whereas •OH in solution would exert the reactivity...
2,249 citations
TL;DR: In this paper, the degradation of chlorophenols (CPs) by means of advanced oxidation processes (AOPs) was evaluated during the period 1995-2002 and different mechanistic degradation pathways were taken into account.
Abstract: Advanced oxidation processes (AOPs) constitute a promising technology for the treatment of wastewaters containing non-easily removable organic compounds. Chlorophenols (CPs) are a group of special interest due to their high toxicity and low biodegradability. Data concerning the degradation of CPs by means of AOPs reported during the period 1995–2002 are evaluated in this work. Among the AOPs, the following techniques are studied: processes based on hydrogen peroxide (H2O2+UV, Fenton, photo-Fenton and Fenton-like processes), photolysis, photocatalysis and processes based on ozone (O3, O3+UV and O3+catalyst). Half-life times and kinetic constants for CP degradation are reviewed and the different mechanistic degradation pathways are taken into account.
2,024 citations
TL;DR: The effect of halides on organic contaminant destruction efficiency was compared for UV/H2O2 and UV/S2O8(2-) AOP treatments of saline waters; benzoic acid, 3-cyclohexene-1-carboxylic acid, and cyclohexanecarboxy Lic acid were used as models for aromatic, alkene, and alkane constituents of naphthenic acids in oil-field waters.
Abstract: The effect of halides on organic contaminant destruction efficiency was compared for UV/H2O2 and UV/S2O82– AOP treatments of saline waters; benzoic acid, 3-cyclohexene-1-carboxylic acid, and cyclohexanecarboxylic acid were used as models for aromatic, alkene, and alkane constituents of naphthenic acids in oil-field waters. In model freshwater, contaminant degradation was higher by UV/S2O82– because of the higher quantum efficiency for S2O82– than H2O2 photolysis. The conversion of •OH and SO4•– radicals to less reactive halogen radicals in the presence of seawater halides reduced the degradation efficiency of benzoic acid and cyclohexanecarboxylic acid. The UV/S2O82– AOP was more affected by Cl– than the UV/H2O2 AOP because oxidation of Cl– is more favorable by SO4•– than •OH at pH 7. Degradation of 3-cyclohexene-1-carboxylic acid, was not affected by halides, likely because of the high reactivity of halogen radicals with alkenes. Despite its relatively low concentration in saline waters compared to Cl–, ...
735 citations
TL;DR: For a given oxidant dose, the selective oxidants were more efficient than hydroxyl radicals for transforming ERMs-containing micropollutants, while hydroxy radicals are capable of transforming micropolutants even without ERMs.
656 citations
TL;DR: Pt/WO3 photocatalyst that oxidizes various substrates under visible light with a sufficient photostability can be applied for solar water treatment.
Abstract: This study aims to understand the visible light photocatalytic activities of platinized WO3 (Pt/WO3) on the degradation of aquatic pollutants and the role of main photooxidants. The presence of Pt on WO3 is known to facilitate the multielectron reduction of O2, which enables O2 to serve as an electron acceptor despite the insufficient reduction potential of the conduction band electrons (in WO3) for the one-electron reduction of O2. The concurrent oxidative reactions occurring on WO3 were markedly enhanced in the presence of Pt and accompanied the production of OH radicals under visible light, which was confirmed by both a fluorescence method (using a chemical trap) and a spin trap method. The generation of OH radicals mainly comes from the reductive decomposition of H2O2 that is produced in situ from the reduction of O2 on Pt/WO3. The rate of in situ production of H2O2 under visible light was significantly faster with Pt/WO3 than WO3. Six substrates that were tested for the visible light (λ > 420 nm) ind...
645 citations
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TL;DR: In this article, the decolorization of indigo trisulfonate (600 nm, pH below 4) was used to determine the concentration of aqueous ozone in the range 0.005 −30 mg 1−1.
1,991 citations
TL;DR: Evidence indicates that the fraction of oxide surface sites occupied by substituted phenols is quite low, and a mechanism for the surface chemical reaction has been postulated to account for these effects.
Abstract: Kinetics of the reaction of manganese(III/IV) oxides with 11 substituted phenols were examined in order to assess the importance of manganese oxides in the abiotic degradation of phenolic pollutants. At pH 4.4, 10/sup -4/ M solutions of substituted phenols reduced and dissolved synthetic manganese oxide particles in the following order: p-methylphenol > p-ethylphenol > m-methylphenol > p-chlorophenol > phenol > m-chlorophenol > p-hydroxybenzoate > o-hydroxybenzoate > 4'-hydroxyacetophenone > p-nitrophenol. Rates of reductive dissolution generally decrease as the Hammett constants of ring substituents become more positive, reflecting trends in the basicity, nucleophilicity, and half-wave potential of substituted phenols. Evidence indicates that the fraction of oxide surface sites occupied by substituted phenols is quite low. The apparent reaction order with respect to (H/sup +/) is not a constant but varies between 0.45 and 1.30 as the pH range, phenol concentration, and phenol structure are varied. A mechanism for the surface chemical reaction has been postulated to account for these effects.
486 citations
393 citations
TL;DR: The photo-oxygenation of furfuryl alcohol (FFA) in water sensitized by naturally occurring dissolved organic materials under visible light is shown to proceed almost exclusively by a singlet oxygen mechanism.
354 citations
TL;DR: In this article, an automated analytical technique for the determination of hydrogen peroxide (H/sub 2/O/sub2/) in the liquid phase has been developed, which is based on the reaction of H /sub 2 /O/Sub 2 with horseradish peroxidase and p-hydroxyphenylacetic acid (POPHA).
Abstract: An automated analytical technique for the determination of hydrogen peroxide (H/sub 2/O/sub 2/) in the liquid phase has been developed. The chemistry of this technique is based on the reaction of H/sub 2/O/sub 2/ with horseradish peroxidase and p-hydroxyphenylacetic acid (POPHA). The resulting reaction forms the fluorescent dimer of POPHA. By use of conventional fluorescence detection techniques a detection limit of 1.2 x 10/sup -8/ M (0.4 ppbm) H/sup 2/O/sup 2/ is obtained for a 1.5-mL aqueous sample. The coefficient of variation is 0.66% at 1.6 x 10/sup -6/ M (53 ppbm). The analytical chemical reaction responds stoichiometrically to both H/sup 2/O/sup 2/ and organic hydroperioxides. To discriminate H/sup 2/O/sup 2/ from organic hydroperioxides, a novel dual-channel chemical flow system has been devised to separately determine total hydroperioxides and organic hydroperioxides. The concentration of H/sup 2/O/sup 2/ is determined by the difference between these two measurements. The system has been tested extensively for potential interferences commonly found in environmental aqueous samples, and none has been observed. 17 references, 4 figures, 2 tables.
324 citations