Horseradish peroxidase-mediated decolourization of Orange II: modelling hydrogen peroxide utilization efficiency at different pH values
| Autor: | Fernando Sebastián García Einschlag, Patricia Monica Haure, Diego Alberto Morales Urrea, Edgardo Martin Contreras |
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| Rok vydání: | 2018 |
| Předmět: |
Health
Toxicology and Mutagenesis Kinetics chemistry.chemical_element INGENIERÍAS Y TECNOLOGÍAS 02 engineering and technology Orange (colour) 010402 general chemistry 01 natural sciences Horseradish peroxidase Oxygen Biotecnología Industrial Absorbance chemistry.chemical_compound Ingeniería de los Materiales Decolourization Environmental Chemistry Coloring Agents Hydrogen peroxide Ciencias Exactas biology Benzenesulfonates Física Orange II General Medicine Hydrogen-Ion Concentration Kinetic model Bioprocesamiento Tecnológico Biocatálisis Fermentación 021001 nanoscience & nanotechnology Pollution 0104 chemical sciences chemistry biology.protein 0210 nano-technology Azo Compounds Oxidation-Reduction Stoichiometry Peroxidase Nuclear chemistry |
| Zdroj: | SEDICI (UNLP) Universidad Nacional de La Plata instacron:UNLP |
| ISSN: | 1614-7499 0944-1344 |
| Popis: | Enzymatic decolourization of azo-dyes could be a cost-competitive alternative compared to physicochemical or microbiological methods. Stoichiometric and kinetic features of peroxidase-mediated decolourization of azo-dyes by hydrogen peroxide (P) are central for designing purposes. In this work, a modified version of the Dunford mechanism of peroxidases was developed. The proposed model takes into account the inhibition of peroxidases by high concentrations of P, the substrate-dependant catalatic activity of peroxidases (e.g. the decomposition of P to water and oxygen), the generation of oxidation products (OP) and the effect of pH on the decolourization kinetics of the azo-dye Orange II (OII). To obtain the parameters of the proposed model, two series of experiments were performed. In the first set, the effects of initial P concentration (0.01–0.12 mM) and pH (5–10) on the decolourization degree were studied at a constant initial OII concentration (0.045 mM). Obtained results showed that at pH 9–10 and low initial P concentrations, the consumption of P was mainly to oxidize OII. From the proposed model, an expression for the decolourization degree was obtained. In the second set of experiments, the effect of the initial concentrations of OII (0.023–0.090 mM), P (0.02–4.7 mM), HRP (34–136 mg/L) and pH (5–10) on the initial specific decolourization rate (q0) was studied. As a general rule, a noticeable increase in q0 was observed for pHs higher than 7. For a given pH, q0 increased as a function of the initial OII concentration. Besides, there was an inhibitory effect of high P concentrations on q0. To asses the possibility of reusing the enzyme, repeated additions of OII and P were performed. Results showed that the enzyme remained active after six reuse cycles. A satisfactory accordance between the change of the absorbance during these experiments and absorbances calculated using the proposed model was obtained. Considering that this set of data was not used during the fitting procedure of the model, the agreement between predicted and experimental absorbances provides a powerful validation of the model developed in the present work. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas |
| Databáze: | OpenAIRE |
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