Uncatalysed oscillatory chemical reactions. Oxidation of 1,4-cyclohexanedione by bromate in perchloric or orthophosphoric acid solution

Farage, Vincent J.; Janjic, D.

doi:10.1016/s0020-1693(00)93484-4

Cited by 12 publications

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“…Electrochemical techniques utilizing potentiometry have been applied for the detection of bromide, such as the use of ion selective electrodes (ISEs). [46][47][48] These electrodes are capable of selectively measuring the concentration of a particular ionic species. The performance of an ISE is based on the selective passage of charged species from one phase to another leading to the creation of a potential difference.…”

Section: Other Techniquesmentioning

confidence: 99%

Bromate analysis in groundwater and wastewater samples

et al. 2005

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Bromate (BrO(3)(-)) is a disinfection by-product formed during ozonation of potable water supplies containing bromide (Br(-)). Bromate has been classed by the World Health Organisation as a 'possible human carcinogen', leading to implementation of 10-25 microg L(-1)(as BrO(3)(-)) drinking water limits in legislative areas including the United States and European Union. Techniques have been developed for bromate analysis at and below regulatory limits, with Ion Chromatography (IC) coupled with conductivity detection (IC-CD), post-column reaction and ultra-violet (UV) detection (IC-PCR), or inductively coupled plasma-mass spectrometry detection (IC-ICPMS) in widespread use. The recent discovery of bromate groundwater contamination in a UK aquifer has led to a requirement for analysis of bromate in a groundwater matrix, for environmental monitoring and development of remediation strategies. The possibility of bromate-contaminated water discharge into sewage treatment processes, whether accidental or as a pump-and-treat strategy, also required bromate analysis of wastewater sources. This paper summarises techniques currently available for trace bromate analysis in potable water systems and details studies to identify a methodology for routine analysis of groundwater and wastewater samples. Strategies compared were high performance liquid chromatography (HPLC) with direct UV or PCR/UV detection, IC-CD, IC-PCR, and a simple spectrophotometric technique. IC-CD was the most cost-effective solution for simultaneous analysis of bromate and bromide within groundwater samples, having a 5 microg L(-1) detection limit of both anions with limited interference from closely-eluting species. Wastewater samples were successfully analysed for bromate only using HPLC with PCR/UV detection, with detection limits below 20 microg L(-1)(as BrO(3)(-)) and low interference. HPLC with direct UV detection was unsuitable for bromate analysis within the concentration range 50-5000 microg L(-1) which was required for this project, but column choice was shown to be a major factor in determining limits of detection. Spectrophotometry could not reproducibly determine bromate concentration, although the technique showed promise as a quick field method for high-level groundwater bromate analysis.

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Section: Other Techniquesmentioning

confidence: 99%

Bromate analysis in groundwater and wastewater samples

et al. 2005

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“…One particular system suggested by Farage and Janjic [94], with substrate 1,4-cyclohexanedione (CHD), oscillates in four different acid solutions (HNO 3 , H 2 SO 4 , HClO 4 , H 3 PO 4 ). Kurin-Csorgei et al investigated this reaction further and proposed a skeleton kinetic scheme for this system, involving the oxidation of CHD to give the hydroquinone and quinone [95].…”

Section: (I)mentioning

confidence: 99%

Mechanism and Phenomenology of an Oscillating Chemical Reaction

Taylor

2002

Progress in Reaction Kinetics and Mechanism

120

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Chemical reactions, which are far from equilibrium, are capable of displaying oscillations in species concentrations and hence in colour, electrode potential, pH and/or temperature. The oscillations arise from the interplay between positive and negative kinetic feedback. Mechanisms for such reactions are presented, along with the rich phenomenology that these systems exhibit, from complex oscillations and chemical waves, to stationary concentration patterns. This review will focus on the Belousov-Zhabotinksy reaction but reference to other reactions will be made where appropriate.

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“…Several experimental techniques have been used to elucidate the reaction mechanism of the UBOphenol. The most common is potentiometry using either platinum [11][12][13][14][15][16] or bromide selective electrodes [12,14,15]. Nonetheless, these techniques present two major drawbacks: The source of the redox potential oscillations is not well understood as in the catalyzed systems, and the interference produced by the highly passivating medium over the electrode [17].…”

Section: Introductionmentioning

confidence: 99%

Ultraviolet-Visible Kinetic Study of the Uncatalyzed Bromate Oscillator with Phenol by Multivariate Curve Resolution

Robayo-Molina

Ágreda

2017

Int. J. Chem. Kinet.

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A kinetic study of the uncatalyzed bromate oscillator (UBO) using phenol was carried out by chemometric analysis of the UV/Vis data. The reaction was studied with different starting concentrations of the reagents (sulfuric acid and potassium bromate) and by changing phenol for 2-bromophenol and 4-bromophenol. The number of chemical absorbing species involved in the UV/Vis data was established by singular value decomposition and by the residual fit parameter. Multivariate curve resolution with alternating least squares generated valuable information about the different chemical species along the process (spectral and concentration profiles). These results show the presence of four principal components: two intermediates and two products. The products can be assigned as o-quinone and 4,4 -diphenoquinone, and the principal components associated with the intermediates represent the linear combination of all the intermediates in the reaction mixture. These data were used to generate a model of the UBO-phenol oscillator that reproduces qualitatively the experimental results. C

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Uncatalysed oscillatory chemical reactions. Oxidation of 1,4-cyclohexanedione by bromate in perchloric or orthophosphoric acid solution

Cited by 12 publications

References 0 publications

Bromate analysis in groundwater and wastewater samples

Bromate analysis in groundwater and wastewater samples

Mechanism and Phenomenology of an Oscillating Chemical Reaction

Ultraviolet-Visible Kinetic Study of the Uncatalyzed Bromate Oscillator with Phenol by Multivariate Curve Resolution

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