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Start Over Descriptor "Briggs–Rauscher reaction" Language serbian
3 results on '"Briggs–Rauscher reaction"'

1. Oscillatory reaction as a system detector for doped and undoped phosphate tungsten bronzes

Author

Maksimović Tijana V., Maksimović Jelena P., Joksović Ljubinka G., Nedić Zoran P., and Pagnacco Maja C.

Subjects
bronzes, phosphate tungsten bronzes, oscillatory reaction, Briggs-Rauscher reaction, nonlinear phenomena, Chemical technology, TP1-1185
Abstract

Phosphate tungsten bronzes, obtained by thermal treatment, are insufficiently investigated bronzes and there is scarce literature data on their chemical behavior and structure. Due to high-sensitivity of the Briggs-Rauscher (BR) reaction to addition of different analytes, this oscillatory reaction presents a potentially important chemical system for investigation and characterization of phosphate-tungsten bronzes, doped and undoped. The reaction mixture for the oscillatory BR reaction typically consists of H2O2, HClO4, KIO3, Mn(II) (catalyst), and CH2(COOH)2 (malonic acid, as an organic substrate). This paper deals with phosphate tungsten bronzes (PWB) and lithium doped phosphate tungsten bronzes (LiPWB) and their effects on the Briggs-Rauscher reaction dynamics. It is shown that the addition of phosphate tungsten bronzes decreases the oscillatory period length in this reaction. Furthermore, the obtained results show that PWB has a stronger influence on the BR reaction dynamics then LiPWB. In both cases, the oscillatory period is a linear function of the added bronze mass. The obtained linear functions can be successfully used for determination of the unknown bronze mass. Furthermore, due to different slopes of these functions, the Briggs-Rauscher reaction can be used as a system-detector for lithium doped and undoped phosphate tungsten bronzes. In order to elucidate the mechanism of bronze action, the inductively coupled plasma optical emission spectrometry (ICP-OES) was used to measure the total contents of K, Mn, W, Li. The aliquots of the above solution (i.e. CH2(COOH)2, MnSO4, HClO4, KIO3 but without H2O2) with the identical masses of PWB and LiPWB were examined. For the sake of comparison, contents of the metals in the solution without the bronze addition were measured, as well. Results obtained by the ICP-OES analysis show that the bronze structure is disturbed in the strong oxidizing environment (iodate in acidic solution) so that both, tungsten and lithium, leach into the BR solution. Accordingly, the proposed mechanism of the bronze action is probably by the reaction of tungsten ion with hydrogen-peroxide resulting in formation of a tungsten-peroxo complex. This complex is a stronger oxidizing agent then hydrogen peroxide itself. Thus, formation of the tungsten-peroxo complex potentially affects the kinetics of the Briggs-Rauscher reaction. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. 172015, Grant no. III45001 and Grant no. III45014]

Published
2018
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2. Briggs-Rauscher reaction as a novel electrochemical detector for phosphate tungsten and phosphate molybdenum bronzes

Author

Maja C. Pagnacco, Jelena P. Maksimović, Tihana Mudrinić, Zorica Mojović, and Zoran Nedić

Subjects
Analyte, Oscillatory reactions, General Chemical Engineering, Inorganic chemistry, Phosphate molybdenum bronze, Briggs-Rauscher reaction, chemistry.chemical_element, Molybdenum bronze, 02 engineering and technology, Tungsten, 010402 general chemistry, 01 natural sciences, Analytical Chemistry, Catalysis, chemistry.chemical_compound, Bronzes, Electrochemistry, 021001 nanoscience & nanotechnology, 0104 chemical sciences, Briggs–Rauscher reaction, chemistry, Molybdenum, Cyclic voltammetry, Inductively coupled plasma, 0210 nano-technology, Phosphate tungsten bronze
Abstract

Briggs-Rauscher (BR) oscillatory reaction is a chemical system very sensitive to different analyte addition. Changes in oscillatory dynamics, by analyte addition, could be successfully used for the determination of analyte concentration, as well as for its antioxidative/antiradical activity assessment. In this work, the BR reaction is used as a system detector for distinguishing solid unsolvable materials, such as phosphate tungsten bronze (PWB) and phosphate molybdenum bronze (PMoB), obtained by thermal treatment. The addition of different masses of PWB in BR reaction decreases its oscillation time, while the addition of different masses of PMoB had no effects on the BR oscillation time. Additionally, the BR oscillation time is the linear function of added PWB mass. The mechanism of bronzes action is investigated by using pH and electric conductivity measurements, as well as inductively coupled plasma and the cyclic voltammetry measurements, and it can be ascribed to PWB better catalytic activity then PMoB, under BR reaction condition. This work extends the practical aspect of the BR reaction for testing solid (insoluble) materials, and opening the possibility of using oscillatory reactions in material science and catalysis, in general.

Published
2019

3. Intermitentna haotična stanja u oksihalogenidnim oscilatornim reakcijama

Author

Bubanja, Itana Nuša, Stanisavljev, Dragomir, Čupić, Željko, Vukelić, Nikola, and Ivanović-Šašić, Ana

Subjects
intermittent chaos, Briggs-Rauscher reakcija, intermittent oscillations, Lyapunov-ljev eksponent, Briggs-Rauscher reaction, intermitentne oscilacije, Bray-Liebhafsky reaction, intermitentan haos, Lyapunov exponent, Bray-Liebhafsky reakcija
Abstract

Oscilatorna dinamička stanja su veoma česta u prirodim procesima i stoga važna za postojanje živog sveta. Složeni prirodni sistemi poseduju veliki broj vrsta koje međusobno interaguju na različite načine i kao takvi su veoma komplikovani, ili gotovo nemogući, za detaljna eksperimentalna istraživanja, pa je potrebno da se osnovni fenomeni ispitaju u jednostavnijim hemijskim oscilatorima. U ove jednostavnije hemijske oscilatore spadaju oksihalogenidni oscilatori, od kojih su najpoznatiji Bray-Liebhafsky i Briggs-Rauscher predmet ove teze. U uzanom delu oscilatorne oblasti mogu se zapaziti i aperiodična dinamička stanja odnosno haos. Poseban oblik haosa predstavljaju intermitentne oscilacije odnosno intermitentan haos. Intermitentan haos je ono haotično stanje gde se dva kvalitativno različita dinamička stanja naizmenicno i haotično smenjuju, pri konstantnim vrednostima kontrolnih parametara. Kao takav uočen je u mnogim složenim nelinearnim sistemima mada su saznanja o intermitentnim stanjima u oksihalogenidnim sistemima veoma skromna. Intermitentan haos, koji je u okviru ove teze eksperimentalno generisan, predstavlja haotičnu i naizmeničnu smenu intervala oscilacija velikih amplituda i intervala oscilacija malih amplituda. Za eksperimentalno praćenje intermitentnog haosa u ovoj tezi je korišćena potenciometrijska metoda, koja se inače široko primenjuje za praćenje dinamike hemijskih oscilatora. U oba oksihalogenidna sistema, obuhvaćena tezom, intermitentne oscilacije su uočene u zatvorenom i otvorenom reaktoru, i to u uzanom intervalu kontrolnih parametara u Bray-Liebhafsky sistemu i u uzanom opsegu koncentracija hemijskog perturbatora u Briggs-Rauscher sistemu. Kako bi se omogućila kvantitativna analiza dobijenih rezultata u okviru teze su razvijene i nove metode analize eksperimentalno dobijenog intermitentnog haosa. Pored toga pojedini rezultati su analizirani i primenom numeričkih metoda, poput onih koja se često koriste u analizi haosa, i to Poincaré-ove mape, Lyapunov-ljevi eksponenti i autokorelaciona metoda. Oscillatory dynamic states are very common in natural processes and therefore very important for existence of the living world. Complex natural processes have numerous species that interact between one another in different manners, and so they are very complicated, or almost impossible, for detailed experimental investigations, so principal phenomena sould be examined in simpler chemical oscillators. Such systems are oxi-halide oscillators. The most famous oxi-halide oscillators are Bray-Liebhafsky and Briggs-Rauscher and they are the object of study in this thesis. In the narrow part of the oscillatory region, aperiodic dynamic states or chaos can be found. Intermittent oscillations or intermittent chaos represents a specific form of the chaotic state. Intermittent chaos is considered a chaotic state where transition between two qualitatively different dynamic states occurs randomly and wherein control parameters are constant. As such it was found in many complex nonlinear systems, however knowledge about intermittent states in oxi-halide systems are very modest. Experimentally generated intermittent chaos, within this thesis, represents dynamic state where intervals of high-amplitude oscillations chaotically alternate with intervals of low-amplitude oscillations. For experimental recording of the intermittent chaos, within this thesis, a potentiometric method was used. This method is widely used to follow the dynamics of the chemical oscillators. In this thesis, in both oxi-halide systems, intermittent oscilations were found in open and in closed reactor. Namely, intermitent oscillations were found in narrow interval of control parameters in Bray-Liebhafsky and in narrow range of concentrations of the chemical perturbator in Briggs-Rauscher reaction system. In order to allow quantitative analysis of obtained results, in this thesis new methods of the analysis of the experimentaly obtained intermittent states are developed. Besides, some results were analysed by numerical methods like Poincaré maps, Lyapunov exponents and autocorrelation function since those methods are often used in the analysis of chaos.

Published
2017

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