Selective chemical oxidation or reduction of chlorophenols with potassium nitrosodisulfonate

Leyva, Elisa; Crispin, Ismael; Moctezuma, Edgar; Leyva, Socorro

doi:10.3998/ark.5550190.0004.b21

Cited by 4 publications

(4 citation statements)

References 21 publications

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“…Detailed EPR measurements are presented that investigate the formation of photoinduced paramagnetic centers in support of the information obtained by the photocatalytic tests. Note that a study of the degradation mechanism and identification of intermediate reaction products of the pollutants lies beyond the scope of this article and has already been thoroughly described in the literature. − The outcome of the latter studies is used here in the interpretation of the obtained data.…”

Section: Resultsmentioning

confidence: 99%

“…Note that a study of the degradation mechanism and identification of intermediate reaction products of the pollutants lies beyond the scope of this article and has already been thoroughly described in the literature. [15][16][17] The outcome of the latter studies is used here in the interpretation of the obtained data.…”

Section: Measurement Of Photocatalytic Activity By Uv-vis Analysis (P...mentioning

confidence: 99%

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Unraveling the Photocatalytic Activity of Multiwalled Hydrogen Trititanate and Mixed-Phase Anatase/Trititanate Nanotubes: A Combined Catalytic and EPR Study

et al. 2011

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A detailed study of the photocatalytic activity of hydrogen trititanate nanotubes (H-TNT), formed by a hydrothermal treatment, was carried out. H-TNT show a limited activity toward pyridinium chloride degradation under UV-light and even no activity under visible light. In contrast, H-TNT show activity toward the degradation of rhodamine 6G (R6G), both under UV and visible light. EPR spectroscopy is used to gain insight into this difference. UV-light excitation of H-TNT leads to the predominant formation of Ti 3þ centers by trapping of electrons at Ti sites, whereas almost no reactive oxygen-based species are formed. Upon visible light excitation of these nanotubes, no light-induced EPR signals are observed. The activity toward R6G degradation thus stems from the excitation of R6G (under both UV and visible light) and the subsequent transfer of electrons into the conduction band of TiO 2 . After a short calcination process at 623 K, the H-TNT undergo a partial phase transformation into anatase, without affecting the shape and morphology of the nanotubes, and the photocatalytic activity increases to a great extent. The EPR analysis now reveals the formation of different types of species characterized by g values larger than g e , both upon UV and visible light excitation. These reactive species, such as O 2 -and O -, are known to play an important role in the photocatalytic process.

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Section: Resultsmentioning

confidence: 99%

Section: Measurement Of Photocatalytic Activity By Uv-vis Analysis (P...mentioning

confidence: 99%

Unraveling the Photocatalytic Activity of Multiwalled Hydrogen Trititanate and Mixed-Phase Anatase/Trititanate Nanotubes: A Combined Catalytic and EPR Study

et al. 2011

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“…Chlorophenols are catalogued as one of the priority pollutants (Clean Water Act and by European Directive 2013/39/EU) according to the United States Environmental Protection Agency (US EPA) 1 – 3 because they are toxic and potentially carcinogenic compounds 2 . They are considerate one of the most important classes of water contaminants due to they are difficult to remove from the environment 2 – 5 and they can appear in drinking water when hypochlorite reacts during water disinfection 4 . Thus, they are of great concern.…”

Section: Introductionmentioning

confidence: 99%

Kinetic modelling for concentration and toxicity changes during the oxidation of 4-chlorophenol by UV/H2O2

Ferreiro

Sanz

Villota

et al. 2021

Sci Rep

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This work develops a kinetic model that allow to predict the water toxicity and the main degradation products concentration of aqueous solutions containing 4-chlorophenol oxidised by UV/H2O2. The kinetic model was developed grouping degradation products of similar toxicological nature: aromatics (hydroquinone, benzoquinone, 4-chlorocatechol and catechol), aliphatics (succinic, fumaric, maleic and malonic acids) and mineralised compounds (oxalic, acetic and formic acids). The degradation of each group versus time was described as a mathematical function of the rate constant of a second-order reaction involving the hydroxyl radical, the quantum yield of lump, the concentration of the hydroxyl radicals and the intensity of the emitted UV radiation. The photolytic and kinetic parameters characterising each lump were adjusted by experimental assays. The kinetic, mass balance and toxicity equations were solved using the Berkeley Madonna numerical calculation tool. Results showed that 4-chlorophenol would be completely removed during the first hour of the reaction, operating with oxidant molar ratios higher than R = 200 at pH 6.0 and UV = 24 W. Under these conditions, a decrease in the rate of total organic carbon (TOC) removal close to 50% from the initial value was observed. The solution colour, attributed to the presence of oxidation products as p-benzoquinone and hydroquinone, were oxidised to colourless species, that resulted in a decrease in the toxicity of the solutions (9.95 TU) and the aromaticity lost.

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“…Thus, the effect of chloride ions on CP oxidation kinetics should be demonstrated in detail. There was different reactivity for different CPs with different positions of chloride atoms due to the σ-electron withdrawing conductive effect, π-electron donating conjugative effect, and steric hindrance effect of chlorine (Tang and Huang 1995;Leyva et al 2003;Zhang et al 2003;Zhou et al 2011). It was speculated that Cl − might exhibit different inhibitory effects on the oxidation rate of CPs with different substituent positions of chlorine on the phenyl ring.…”

Section: Introductionmentioning

confidence: 99%

Kinetics of Inhibition of Dichlorophenol Oxidation by NaCl over Fe-Cu-Pillared Clay

Zhou

He²,

2019

J. Environ. Eng.

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Catalytic wet peroxide oxidation (CWPO) of dichlorophenols (DCPs) over Fe-Cu-pillared clay (PILC) without and with NaCl was investigated. Concentration change dynamics in H 2 O 2 , Cl − , and hydroxyl radicals (•OH) during DCP oxidation were also studied. Additionally, the intermediates formed were detected by liquid chromatography-mass spectroscopy (LC-MS). The results showed that the presence of NaCl inhibited the DCP oxidation rate to some extent, where induction time (T I) was lengthened from 75.9 to 93.6 min, and half-decomposition time (T 1=2) was extended to 20.6 min (from 86.6 to 107.2 min) as compared with control (without NaCl addition). However, NaCl only strongly inhibited the oxidation rate of ortho-substituted DCPs such as 2,6-DCP, where T I was lengthened to 80 min (from 290.7 to 370.4 min), but not meta-DCPs or para-DCPs. Further investigation showed that NaCl did not affect the conversion (dechlorination and hydroxylation) of DCPs and also did not change the DCP oxidation path. It was hypothesized that the inhibitory mechanism of NaCl on ortho-DCP oxidation was mainly due to inhibiting the rate-limiting step of H 2 O 2 decomposition (lengthening the induction period from 350 to 510 min) by competing with H 2 O 2 for the complexation of Fe (III), secondary due to scavenging of •OH (about 21%) to form chlorine radicals such as •Cl − 2 .

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Selective chemical oxidation or reduction of chlorophenols with potassium nitrosodisulfonate

Cited by 4 publications

References 21 publications

Unraveling the Photocatalytic Activity of Multiwalled Hydrogen Trititanate and Mixed-Phase Anatase/Trititanate Nanotubes: A Combined Catalytic and EPR Study

Unraveling the Photocatalytic Activity of Multiwalled Hydrogen Trititanate and Mixed-Phase Anatase/Trititanate Nanotubes: A Combined Catalytic and EPR Study

Kinetic modelling for concentration and toxicity changes during the oxidation of 4-chlorophenol by UV/H2O2

Kinetics of Inhibition of Dichlorophenol Oxidation by NaCl over Fe-Cu-Pillared Clay

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