Made available in DSpace on 2017-07-10T18:08:15Z (GMT). No. of bitstreams: 1 Diego Ricieri Manenti.pdf: 2926963 bytes, checksum: 74aa89bdde44c5ef6942846129864678 (MD5) Previous issue date: 2011-02-25 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The aim of this work was to study the performance of the photo-Fenton process using both the artificial UV and solar sources on the textile effluent treatments. Preliminary photo-Fenton experiments for mineralization and degradation of organic and inorganic pollutants as well as of synthetic dyes were carried out in order to assess the best experimental conditions by photo-Fenton process. As synthetic textile effluent a mixture of six dyes: Solophenyl orange TGL (C25H33ClN6O6S2), Solophenyl blue 71 (C40H23N7Na4O13S4), Solophenyl scarlet BNLE (C44H32N10Na4O16S4), Solophenyl yellow ARL (C48H26N8Na6O18S6), Solophenyl black FR (C44H32N13Na3O11S3) e Navy Blue 98 (C38H24N5Na3O13S3) that contained 50 mg L-1 concentration was prepared and diluted in distillated water. The photo-Fenton experiments by using a set of high-pressure mercury lamps and solar light as artificial and natural UV irradiation sources were performed in laboratory scale. As reactor operational parameters to be optimized by a 33 full factorial experimental design: hydrogen peroxide and divalent iron ion as well as the initial solution pH were chosen as variables, keeping constant a reaction time of 120 min that was enough to warrant the maximum (chemical oxygen demand) COD and color removal. The efficiency of photo-Fenton process applied in the treatment of synthetic and real effluents, was evaluated based on the parameters: values of COD, color, turbidity, total organic carbon (TOC), absorbance at a wavelength of maximum absorption for the dyes and simple aromatic compounds and conjugated reductions, as well as behavior analysis of the evolution the sulfate, nitrate inorganic, organic nitrogen and ammonia concentrations. Second-degree models for the COD and color removal percents were proposed to model the photo-Fenton experiments data in order to reduce the cost of running such a photo-Fenton experiment as well as to obtain optimum values of the reactor operating parameters. Second-degree models were also validated by ANOVA. Predicted yields showed good validation with experimental yields. The values of the optimized reactor operational parameters were 3.0, 6.0 g L-1, and 0.05 g L-1 for initial pH, hydrogen peroxide and divalent iron concentrations, respectively, for both photo-Fenton processes. Based on this optimized experimental conditions, almost 100% removals of physico-chemical parameter such as COD, color, turbidity and COT for real textile effluents. The aromatics compounds were showed more resistant to reaction, persisting for longer. It can be noticed that the degradtion of the organic and inorganic matters were verified by the nitrification process and, the sulfates formation and reduction. The process presented similar efficiencies with both solar and artificial irradiation, thus suggesting the use of solar photo-Fenton, as it proved to be an efficient alternative besides using a source of clean and renewable energy. / O objetivo deste trabalho é avaliar o desempenho do processo foto-Fenton, utilizando energia solar e artificial como fontes de irradiação UV, no tratamento de efluentes têxteis. Foram realizados experimentos preliminares para avaliar a eficiência do processo foto-Fenton na mineralização e degradação dos poluentes orgânicos e inorgânicos, bem como dos corantes sintéticos. Para tanto, foi preparado o efluente têxtil sintético pela mistura de seis corantes: Laranja TGL (C25H33ClN6O6S2), Azul FGLE (C40H23N7Na4O13S4), Escarlate BNLE (C44H32N10Na4O16S4), Amarelo ARLE (C48H26N8Na6O18S6), Preto FR (C44H32N13Na3O11S3) e Marinho BLE (C38H24N5Na3O13S3), em água destilada, com concentração de 50 mg L-1. Os experimentos foram realizados em reatores de escala laboratorial utilizando fontes de irradiação UV natural e artificial. Os parâmetros operacionais dos reatores: pH inicial e a concentração dos reagentes H2O2 e Fe2+, foram otimizados baseados nos valores da demanda química de oxigênio (DQO) e descoloração, a partir de um planejamento fatorial 33 completo com o tempo de irradiação constante em 120 minutos. A eficiência do processo foto-Fenton, aplicado no tratamento dos efluentes sintético e real, foi avaliada baseada nos parâmetros: redução dos valores da DQO, cor, turbidez, carbono orgânico total (COT), absorvância nos comprimentos de onda de máxima absorção relativos aos corantes e aos compostos aromáticos simples e conjugados, além da análise do comportamento da evolução das concentrações de sulfato, nitrato inorgânico, nitrogênio orgânico e amoniacal. Para auxiliar na obtenção das condições ótimas dos parâmetros operacionais do reator e redução dos custos do processo foto-Fenton, as respostas experimentais para a redução da DQO e da cor foram ajustados por um modelo previsto de segunda ordem, o qual apresentou uma boa modelagem dos dados, validado pela ANOVA. Os valores ótimos operacionais do reator, para ambos os processos foto-Fenton no tratamento do efluente real, foram: pH = 3,0, concentração de H2O2 = 6,0 g L-1 e concentração de Fe2+ = 0,05 g L-1. Nestas condições, foram obtidos valores próximos a 100% de redução dos parâmetros físico-químicos DQO, cor, turbidez e COT. Os compostos aromáticos se mostraram mais resistentes a reação, persistindo por mais tempo. A degradação da matéria orgânica e inorgânica foi verificada analisando a evolução do processo de nitrificação e a formação ou redução de sulfatos. Os processos apresentaram eficiências similares tanto com irradiação solar como artificial, desta forma, sugere-se a utilização do processo foto-Fenton solar, pois mostrou ser uma alternativa eficiente além de utilizar uma fonte de energia limpa e renovável.

Tesis por compendio / [ES] Los procesos (foto-)Fenton fueron empleados para degradar fluoroquinolonas (FQ) (una clase de antibióticos sintéticos considerados CEC) como contaminantes modelo en diferentes condiciones: pH (3 - 8), concentración de contaminante (3 - 300 μM), número de FQ presentes (1, 3 y 5), y matrices de agua (agua ultrapura, salina y de WWTP simulada). Los experimentos se realizaron a escala banco y planta piloto, empleando luz solar (simulada y real) e irradiaciones con luz ultravioleta. Las velocidades de degradación de los contaminantes obtenidas con procesos tipo-Fenton se compararon con las análogas de fotólisis, fotocatálisis heterogénea y H2O2/UV. En igualdad de condiciones, solo a través del proceso foto-Fenton se logró una mineralización significativa de las FQs. En aquellos casos en los que el carbono orgánico total no mostró una disminución considerable, la razón se atribuye a la liberación de subproductos de oxidación. EEM-PARAFAC ha demostrado ser una técnica económica, veloz y que no requiere del uso de reactivos, para seguir simultáneamente la eliminación de la degradación de hasta 5 FQs fluorescentes presentes en una misma muestra, en presencia de interferencias sin calibrar, y obtener información sobre las posibles estructuras moleculares de los intermediarios de reacción. Los resultados indicaron que la fotólisis por sí sola no es capaz de producir cambios importantes en la estructura de las FQs, mientras que con (foto-)Fenton sí que se observó una notable disminución de los scores de los componentes PARAFAC asociados con los compuestos del tipo FQ. Los ensayos de zona de inhibición empleando E. coli mostraron que la actividad antibiótica disminuyó en paralelo con la desintegración de todos los componentes PARAFAC relacionados con las FQs y subproductos similares a estas. El otro aspecto importante de la tesis fue el uso de procesos Fenton basados en ZVI. Algunos CEC, como los compuestos nitroaromáticos, exhiben tasas de degradación lentas incluso cuando son degradadas por una AOP. El desarrollo de trenes de tratamiento ZVI para la degradación de contaminantes ha despertado un gran interés en los últimos años. Este enfoque consiste en un primer pretratamiento solo con ZVI (es decir, reducción, deshalogenación), seguido del proceso Fenton aprovechando los iones de hierro liberados en el primer paso. Con el fin de analizar las posibles ventajas e inconvenientes de esta estrategia en las aplicaciones de tratamiento de aguas residuales, se ha estudiado este enfoque empleando micropartículas de ZVI (mZVI) comerciales utilizando ácido p-nitrobenzoico (PNBA) como contaminante modelo. Se analizó el efecto de la cantidad inicial de mZVI, H2O2, pH, conductividad, aniones y oxígeno disuelto. Utilizando agua natural en condiciones aeróbicas, pH inicial 3,0, y adicionando 1,4 g/L de mZVI, se consiguió en 2 h una reducción del 83% de PNBA 6 μM en ácido p-aminobenzoico (PABA). Se investigó también la conveniencia de separar las mZVI después de la fase reductora (antes de la etapa Fenton) así como la reutilización de las mZVI. El paso de Fenton contra el PABA, más reactivo que PNBA, requirió 50 mg/L de H2O2 para lograr una eliminación de más del 96% en 15 min a pH 7,5 (pH final del pretratamiento reductivo). Las mZVI reutilizadas fueron efectivas por lo menos por un ciclo completo (reducción/oxidación). Este enfoque puede ser interesante para tratar aguas residuales que contienen contaminantes inicialmente resistentes al radical hidroxilo (HO), pero fácilmente reducibles, pudiendo disminuir su carga tóxica y aumentar su reactividad para un paso de oxidación posterior. / [CA] Fenton i foto-Fenton van ser emprats per a degradar fluoroquinolones (FQ) (una classe d'antibiòtics sintètics considerats CEC) com a contaminants model en diferents condicions: pH (3 - 8), concentració de contaminant (3 - 300 μM), nombre de FQ presents (1, 3 i 5), i matriu d'aigua (aigua ultrapura, salada i de WWTP simulada). Els experiments es van realitzar a escala de laboratori i planta pilot, emprant llum solar (simulada i real) i irradiacions amb llum ultraviolada. Les velocitats de degradació de contaminants obtingudes amb processos tipus-Fenton es van comparar amb fotòlisi, fotocatàlisi heterogènia i H2O2/UV. En igualtat de condicions, només a través del procés foto-Fenton es va aconseguir una mineralització significativa de FQ. En aquells casos en els quals el carboni orgànic total no va mostrar una disminució considerable, la raó s'atribueix a l'alliberament de subproductes d'oxidació. EEM-PARAFAC ha demostrat ser una tècnica econòmica, que no requereix de l'ús de reactius, i ràpida, per a seguir simultàniament l'eliminació de la degradació de fins a 5 FQ fluorescents presents en una mateixa mostra, en presència d'interferències sense calibrar, i obtindre informació sobre les possibles estructures moleculars dels intermediaris de reacció. Els resultats van indicar que la fotòlisi per si sola no és capaç de produir canvis importants en l'estructura de les FQ, mentre que amb (foto-)Fenton, sí que es va observar una notable disminució dels scores dels components PARAFAC associats amb el nucli de FQ. Els assajos de zona d'inhibició que empren E. coli van mostrar que l'activitat antibiòtica va disminuir en paral·lel amb la desintegració de tots els components PARAFAC relacionats amb FQ i subproductes similars a FQ. L'altre aspecte important de la tesi va ser l'ús de processos Fenton basats en ZVI. Alguns CEC, com els compostos nitroaromàtics, exhibeixen taxes de degradació lentes fins i tot quan són degradats per un AOP. El desenvolupament de trens de tractament basats en ZVI per a la degradació de contaminants ha despertat un gran interés en els últims anys. Aquesta aproximaciót consisteix en un primer pretractament amb ZVI (és a dir, reducció, deshalogenación), seguit del procés Fenton aprofitant els ions de ferro alliberats en el primer pas. Amb la finalitat d'analitzar els possibles avantatges i inconvenients d'aquesta estratègia en les aplicacions de tractament d'aigües residuals, s'han emprat micropartícules de ZVI (mZVI) comercials. Utilitzant àcid p-nitrobenzoic (PNBA) com a contaminant model, es va analitzar l'efecte de la quantitat inicial de mZVI, H2O2, pH, conductivitat, anions i oxigen dissolt. Utilitzant aigua natural en condicions aeròbiques, pH inicial 3,0, i addicionant 1,4 g/L de mZVI, es va aconseguir en 2 h una reducció del 83% de PNBA 6 μM a àcid p-aminobenzoic (PABA). Es va investigar també la conveniència d'eliminar les mZVI després de la fase reductora (abans de l'etapa Fenton) així com la reutilització de les mZVI. El pas de Fenton front el PABA, més reactiu que PNBA, va requerir 50 mg/L de H2O2 per a aconseguir una eliminació de més del 96% en 15 min a pH 7,5 (pH final del pretractament reductiu). Les mZVI reutilitzades van ser efectives almenys amb un cicle complet (reducció/oxidació). Aquest enfocament pot ser interessant per a tractar aigües residuals que contenen contaminants inicialment resistents al HO, però que es redueixen fàcilment, podent disminuir la seua càrrega tòxica i augmentar la seua reactivitat per a un pas d'oxidació posterior. / [EN] Dark Fenton and photo-Fenton were employed to degrade Fluoroquinolones (FQs) (a class of synthetic antibiotics considered CEC) as model pollutants under different conditions: pH (3 - 8), pollutant concentration (3 - 300 μM), number of present FQs (1, 3 and 5), and water matrix (ultra-pure, salty and simulated wastewater). Experiments were performed at bench and pilot plant scales, employing sunlight (simulated and real) and ultraviolet light irradiations. Obtained pollutant abatement rates with Fenton-related processes were compared with photolysis, heterogeneous photocatalysis and H2O2/UV. At equal conditions, only through photo-Fenton process significant FQs mineralization were achieved. In those cases where total organic carbon had not exhibit a considerable decrease, the reason was attributed to the release of oxidation by-products. Since FQs are fluorescent, we decided to employ fluorescence excitation-emission matrices (EEM) in combination with the chemometric tool, Parallel Factor Analysis (PARAFAC), to track their degradations. Although EEM-PARAFAC related studies are usually focused towards the characterization and monitoring of dissolved organic matter (DOM) in natural waters and wastewater effluents (work also included in this PhD Thesis following the DOM along the different stages of a drinking water plant), it is barely the first time that it is used for the purposes we have here proposed. The objective is demonstrating that EEM-PARAFAC could be a feasible complementary methodology for the study of fluorescent CECs degradations, avoiding the use of expensive and sophisticated techniques (e.g mass spectrometry), not always available. The other important aspect of the PhD Thesis was the use of ZVI-based Fenton processes. Some CECs such as nitroaromatic compounds, exhibit slow degradation rates even with AOPs. The development of new and more efficient ZVI treatment trains for pollutant degradation has been attracting great interest in the last few years. This approach consists of a first pre-treatment only with ZVI (i.e. reduction, dehalogenation), followed by a Fenton oxidation taking advantage of the released iron ions from the first step. In order to analyse the strategy's plausible advantages and potential drawbacks within wastewater treatment applications, reductive/oxidative treatment train based on commercial ZVI microparticles (mZVI) has been studied. The effect of the initial amount of mZVI, H2O2, pH, conductivity, anions, dissolved oxygen were analysed using p-nitrobenzoic acid (PNBA) as model pollutant. 83% reduction of PNBA 6 μM into p-aminobenzoic acid (PABA) was achieved in natural water at initial pH 3.0 and 1.4 g/L of mZVI under aerobic conditions in 2 h. An evaluation of the convenience of removing mZVI after the reductive phase (before the Fenton oxidation one) was investigated together with mZVI reusability. The Fenton step against the more reactive PABA required 50 mg/L of H2O2 to achieve more than 96% removal in 15 min at pH 7.5 (final pH from the pre-reductive step). At least one complete reuse cycle (reduction/oxidation) was obtained with the separated mZVI. This approach might be interesting to treat wastewater containing pollutants initially resistant to hydroxyl radical (HO), but easily reduced, being able to decrease its toxic load as well as increasing its reactivity for a subsequent oxidation step. / Sciscenko, IM. (2021). Emerging Photochemical Processes Involving Iron for Wastewater Treatment [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/177357 / TESIS / Compendio

<p>Cilj&nbsp; ove&nbsp; doktorske&nbsp; disertacije&nbsp; je&nbsp; bio&nbsp; razvoj&nbsp; brzih&nbsp; i&nbsp; pouzdanih&nbsp; voltametrijskih&nbsp; metoda zasnovanih na primeni jednostavnih i savremenih elektroda/senzora na bazi ugljeničnih materijala (ugljenične&nbsp; paste&nbsp; napravljene&nbsp; od&nbsp; grafitnog&nbsp; praha&nbsp; i&nbsp; parafinskog&nbsp; ulja&nbsp; i&nbsp; &scaron;tampanih&nbsp; ugljeničnih elektroda)&nbsp; za&nbsp; određivanje&nbsp; H ₂O₂u&nbsp; odabranim&nbsp; složenim&nbsp; model&nbsp; i&nbsp; realnim&nbsp; uzorcima.&nbsp; U&nbsp; tu&nbsp; svrhu, ispitana je primenljivost različitih radnih elektroda. Amperometrijska&nbsp; metoda&nbsp; zasnovana&nbsp; na&nbsp; elektrodi&nbsp; od&nbsp; ugljenične&nbsp; paste&nbsp; (CPE)&nbsp; zapreminski modifikovane&nbsp; sa&nbsp; 5%&nbsp; (m:m)&nbsp; MnO2 je,&nbsp; pri&nbsp; optimizovanim&nbsp; uslovima&nbsp; i&nbsp; pri&nbsp; radnom&nbsp; potencijalu&nbsp; od 0,40 V&nbsp; u&nbsp; odnosu&nbsp; na&nbsp; zasićenu&nbsp; kalomelovu&nbsp; elektrodu&nbsp; (ZKE)&nbsp; u&nbsp; fosfatnom&nbsp; puferu&nbsp; pH&nbsp; 7,50&nbsp; kao pomoćnom elektrolitu, omogućila kvantifikaciju H ₂O₂ u opsegu koncentracija od 1,4 do 65 &micro;g mL -1 sa&nbsp; relativnom&nbsp; standardnom&nbsp; devijacijom&nbsp; (RSD)&nbsp; manjom&nbsp; od&nbsp; 10%.&nbsp; Ova&nbsp; metoda&nbsp; je&nbsp; primenjena&nbsp; za određivanje sadržaja H ₂O₂u uzorcima podzemne vode iz centralnog Banata (Pokrajina Vojvodina, Srbija)&nbsp; tretirane&nbsp; Fentonovim&nbsp; (Fe²⁺ i&nbsp; H ₂O₂ )&nbsp; i&nbsp; Fentonu-sličnim&nbsp; (Fe ³⁺ i&nbsp; H ₂O₂ )&nbsp; reagensima&nbsp; u&nbsp; cilju uklanjanja&nbsp; prirodnih&nbsp; organskih&nbsp; materija&nbsp; (POM)&nbsp; pri&nbsp; čemu&nbsp; su&nbsp; kori&scaron;ćene&nbsp; različite&nbsp; početne koncentracije&nbsp; gvožđa&nbsp; i&nbsp; različiti&nbsp; odnosi&nbsp; molarnih&nbsp; koncentracija&nbsp; gvožđa&nbsp; i&nbsp; H ₂O₂ .&nbsp; Utvrđeno&nbsp; je&nbsp; da oksidaciono&nbsp; stanje&nbsp; gvožđe&nbsp; (Fe²⁺ ili&nbsp; Fe ³⁺)&nbsp; i&nbsp; molarni&nbsp; odnos&nbsp; jona&nbsp; Fe&nbsp; i&nbsp; H₂O₂ utiču&nbsp; na&nbsp; stepen potro&scaron;nje/razgradnje&nbsp; H₂O₂<br />u&nbsp; podzemnoj&nbsp; vodi&nbsp; sa&nbsp; visokim&nbsp; sadržajem&nbsp; POM.&nbsp; Takođe,&nbsp; u&nbsp; slučaju Fentonu-sličnog&nbsp; procesa,&nbsp; za&nbsp; sve&nbsp; početne&nbsp; koncentracije&nbsp; Fe ³⁺ i&nbsp; H ₂O_{2 ,}&nbsp; signifikantna&nbsp; količina&nbsp; H ₂O₂ostaje&nbsp; neiskori&scaron;ćena,&nbsp; &scaron;to&nbsp; ukazuje&nbsp; na&nbsp; nižu&nbsp; efikasnost&nbsp; ovakvog&nbsp; sistema u&nbsp; poređenju&nbsp; sa&nbsp; Fentonovim procesom.&Scaron;tampana&nbsp; ugljenična&nbsp; elektroda&nbsp; (SPCE)&nbsp; zapreminski&nbsp; modifikovana&nbsp; sa&nbsp; MnO 2 kao medijatorom&nbsp; je&nbsp; primenjena&nbsp; za&nbsp; određivanje&nbsp; sadržaja&nbsp; H₂O₂ u&nbsp; toku&nbsp; Fentonovog&nbsp; (Fe ²⁺ ,&nbsp; H₂O₂ )&nbsp; i vidljivom&nbsp; svetlo&scaron;ću&nbsp; potpomognutog&nbsp; foto-Fentonovog&nbsp; (Fe²⁺,&nbsp; H ₂O₂,&nbsp; h&nu;)&nbsp; procesa&nbsp; uklanjanja neonikotinoidnog&nbsp; insekticida&nbsp; acetamiprida&nbsp; (ACT).&nbsp; Pri&nbsp; optimizovanim&nbsp; uslovima&nbsp; (radni&nbsp; potencijal 0,40&nbsp; V&nbsp; u&nbsp; odnosu&nbsp; na&nbsp; ZKE,&nbsp; fosfatni&nbsp; pufer&nbsp; pH&nbsp; 7,50&nbsp; kao&nbsp; pomoćni&nbsp; elektrolit)&nbsp; amperometrijskog određivanja&nbsp; H ₂O₂ ,&nbsp; postignuta&nbsp; je&nbsp; linearnost&nbsp; u&nbsp; opsegu&nbsp; koncentracija&nbsp; 0,01&ndash;1,24&nbsp; mmol&nbsp; L-1(0,34&ndash; 42,2 &micro;g mL -1<br />) i vrednost RSD nije prelazila 4,2%. U ispitivanimuzorcima (nakon odgovarajućeg<br />pode&scaron;avanja pH vrednosti od 2,8 do 7,5 odmah nakon&nbsp; uzorkovanja radi stopiranja ili maksimalnog usporavanja&nbsp; procesa&nbsp; oksidacije,&nbsp; filtriranja,&nbsp; zamrzavanja&nbsp; i&nbsp; odmrzavanja&nbsp; neposredno&nbsp; pre&nbsp; merenja) sadržaj&nbsp; H ₂O₂ je&nbsp; određen&nbsp; metodom&nbsp; standardnog&nbsp; dodatka&nbsp; analiziranjem&nbsp; odgovarajućih amperometrijskih&nbsp; krivi.&nbsp; Paralelna&nbsp; HPLC-DAD&nbsp; merenja&nbsp; su&nbsp; vr&scaron;ena&nbsp; u&nbsp; cilju&nbsp; praćenja koncentracije/uklanjanja ACT. U slučaju foto-Fentonovog procesa (početne koncentracije 0,31; 2,0 i 3,0 mmol L -1 (70,0; 111,7 i 102,1 &micro;g mL -1 ) za ACT, Fe<br />²⁺ i H ₂O₂, redom) nakon 10 min H ₂O₂je izreagovao, a može se smatrati da je ACT uklonjen nakon 5 min. U toku Fentonovog procesa ACT je&nbsp; uklonjen&nbsp; nakon&nbsp; 20&nbsp; min&nbsp; tretmana&nbsp; i&nbsp; oko&nbsp; 10%&nbsp; početne&nbsp; koncentracije&nbsp; H ₂O₂ je&nbsp; ostalo&nbsp; u&nbsp; sistemu<br />neiskori&scaron;ćeno.CPE&nbsp; je&nbsp; povr&scaron;inski&nbsp; modifikovane&nbsp; kompozitom&nbsp; na&nbsp; bazi&nbsp; nanočestica&nbsp; Pt&nbsp; (&lt;&nbsp; 5&nbsp; nm)&nbsp; i grafitizovanog&nbsp; ugljenika&nbsp; (Pt-C,&nbsp; 10%&nbsp; Pt&nbsp; na&nbsp; Vulkanu&nbsp; XC72)&nbsp;&nbsp; etodom&nbsp; nano&scaron;enja&nbsp; kapi. Nemodifikovana&nbsp; CPE&nbsp; i&nbsp; modifikovana&nbsp; (Pt-C/CPE)&nbsp; su&nbsp;&nbsp; okarakterisane&nbsp; primenom&nbsp; SEM/EDS&nbsp; i&nbsp; CV merenja.&nbsp; Pt-C/CPE&nbsp; je&nbsp; pokazala&nbsp; izuzetne&nbsp; elektrokatalitičke&nbsp; osobine&nbsp; u&nbsp; pogledu&nbsp; elektrohemijskeredoks&nbsp; reakcije&nbsp; H<br />₂O₂ u&nbsp; poređenju&nbsp; sa&nbsp; nemodifikovanom&nbsp; CPE&nbsp; u&nbsp; fosfatnom&nbsp; puferu&nbsp; (0,1 mol&nbsp; L -1 ;<br />pH 7,50),&nbsp; a&nbsp; takođe&nbsp; i&nbsp; u&nbsp; acetatnom&nbsp; puferu&nbsp; (0,1&nbsp; mol&nbsp; L -1 ;&nbsp; pH&nbsp; 4,50)&nbsp; kao&nbsp;&nbsp; pomoćnim&nbsp; elektrolitima. Prilikom&nbsp; amperometrijskog&nbsp; određivanja&nbsp; H ₂O₂ primenom&nbsp; Pt-C/CPE&nbsp; u&nbsp; model&nbsp; sistemima, zadovoljavajuća linearnost je postignuta u koncentracionom opseguH₂O₂od 0,15 do 1,45 &micro;g mL -1 ,dok su vrednosti GO iznosile 0,06 &micro;g mL -1 (pH 7,50, radni potencijal 0,20 V) i 0,10 &micro;g mL -1 (pH<br />4,50,&nbsp; radni&nbsp; potencijal&nbsp; 0,50&nbsp; V).&nbsp; Optimizovane&nbsp; analitičke&nbsp; metode&nbsp; su&nbsp; primenjene&nbsp; za&nbsp; određivanje sadržaja H ₂O₂ u komercijalno dostupnim proizvodima za ličnu negu: rastvoru za dezinfekciju (pH 7,50)&nbsp; i&nbsp; rastvoru&nbsp; za&nbsp; či&scaron;ćenje&nbsp; kontaktnih&nbsp; sočiva&nbsp; (pH&nbsp; 4,50).&nbsp; Amperometrijski&nbsp; dobijeni&nbsp; rezultati&nbsp; su&nbsp; u dobrom&nbsp; slaganju&nbsp; sa&nbsp; rezultatima&nbsp; dobijenim&nbsp; primenom&nbsp; tradicionalne&nbsp; spektrofotometrijske&nbsp; metode bazirane&nbsp; na&nbsp; titanijum-sulfatu&nbsp; kao&nbsp; reagensu&nbsp; sa&nbsp; određenim&nbsp; koncentracijama&nbsp; 2,91%&nbsp; i&nbsp; 2,94%&nbsp; za<br />dezinfekcioni rastvor i 3,04% i 3,17% za rastvor zakontaktna sočiva, redom. RSD je bila manja od 2%.&nbsp; Postignuti&nbsp; rezultati&nbsp; su&nbsp; u&nbsp; dobrom&nbsp; slaganju&nbsp; sa&nbsp; sadržajem&nbsp; H<br />₂O₂deklarisanim&nbsp; od&nbsp; strane proizvođača (3%) u oba ispitivana uzorka. Pt-C/CPE je takođe testirana za praćenje koncentracije H₂O₂ u rastvoru za kontaktna sočiva u toku procesa njegove neutralizacije/razgradnje. Nakon 6 h procesa neutralizacije, 24,68&nbsp; &micro;g mL -1 je bila određena koncentracija H ₂O_{2 ,} &scaron;to je ispod dozvoljene<br />H₂O₂koncentracije u rastvoru za kontaktna sočiva imajući u vidu granicu koja izaziva iritaciju oka. CPE&nbsp; je&nbsp; povr&scaron;inski&nbsp; modifikovana&nbsp; vi&scaron;ezidnim&nbsp; ugljeničnim&nbsp; nanocevima&nbsp; (MWCNT)&nbsp; i kompozitima MnO 2 -MWCNT ili Pt-MWCNT metodom nano&scaron;enja kapi radi pripreme jednostavnih, osetljivih i pouzdanih voltametrijskih senzora za&nbsp; određivanje H ₂O₂u odabranom uzorku. Rezultati SEM/EDS&nbsp; analize&nbsp; kompozitnih&nbsp; materijala&nbsp; su&nbsp; potvrdili da&nbsp; su&nbsp; medijatori,&nbsp; čestice&nbsp; MnO 2 i&nbsp; Pt, nasumično&nbsp; raspoređeni na povr&scaron;ini MWCNT i zastupljeni sa blizu 5% (m:m) u kompozitu izraženo<br />preko Mn i Pt. CV merenja su vr&scaron;ena sa pripremljenim radnim elektrodama u acetatnom (pH 4,50), fosfatnom&nbsp; (pH&nbsp; 7,50)&nbsp; i&nbsp; boratnom&nbsp; (pH&nbsp; 9,18)&nbsp; puferu&nbsp; kako&nbsp; bi&nbsp; se&nbsp; okarakterisalo&nbsp; osnovno elektrohemijsko&nbsp; pona&scaron;anje&nbsp; H ₂O₂i&nbsp; odabrali&nbsp; pogodni&nbsp; radni&nbsp; potencijali&nbsp; za&nbsp; amperometrijsko određivanje ovog ciljnog analita. Pt- WCNT/CPE je primenljiva za rad kako u fosfatnom puferu pH&nbsp; 7,50&nbsp; tako&nbsp; i&nbsp; u&nbsp; acetatnom&nbsp; puferu&nbsp; pH&nbsp; 4,50&nbsp; V&nbsp; kako&nbsp; pri&nbsp; negativnim&nbsp; tako&nbsp; i&nbsp; pri&nbsp; pozitivnim&nbsp; radnim<br />potencijalima, pri&nbsp; čemu su vrednosti RSD uglavnom ispod 2,5%. U slučaju MnO 2<br />-MWCNT/CPE, na&nbsp; potencijalu&nbsp; 0,30&nbsp; V&nbsp; i&nbsp; vi&scaron;im&nbsp; vrednostima,&nbsp; oksidacioni&nbsp; signali&nbsp; H<br />₂O₂ su&nbsp; signifikantni&nbsp; u&nbsp; blago alkalnoj sredini (pH 7,50), pri pH 4,50 ova elektroda pokazuje nezadovoljavajuće pona&scaron;anje, dok&nbsp; pri pH 9,18 ima prihvatljive performanse. Granice određivanja (GO) su bile u oblasti &micro;g mL -1 . H ₂O₂ je&nbsp; određen&nbsp; u&nbsp; spajkovanom&nbsp; uzorku&nbsp; mleka&nbsp; metodom&nbsp; standardnog&nbsp; dodatka&nbsp; nakon&nbsp; odgovarajuće pripreme&nbsp; uzorka&nbsp; (pH&nbsp; pode&scaron;avanje&nbsp; i&nbsp; centrifugiranje)&nbsp; i&nbsp; primenom&nbsp; optimizovane&nbsp; amperometrijske procedure (acetatni pufer pH 4,50, radni&nbsp; potencijal-0,75 V) koristeći Pt-MWCNT/CPE kao radnu elektrodu. RSD za tri&nbsp; ponovljena merenja je iznosila 2,5%, dok je prinos metode bio ne&scaron;to veći od 71%.<br />Kompozitni materijali koji se sastoje od MWCNT i&nbsp; čestica na bazi Pd (Pd-MWCNT) ili Pt (Pt-MWCNT) su primenjeni za pripremu zapreminski modifikovanih SPCE (Pd-MWCNT-SPCE i Pt-MWCNT-SPCE)&nbsp; i&nbsp; povr&scaron;inski&nbsp; modifikovane&nbsp; SPCE&nbsp; (Pd-MWCNT/SPCE).&nbsp; Ove&nbsp; elektrode,&nbsp; kao&nbsp; i nemodifikovana&nbsp; SPCE&nbsp; i&nbsp; MWCNT-SPCE,&nbsp; su&nbsp; okarakterisane primenom&nbsp; CV&nbsp; i&nbsp; amperometrije&nbsp; u fosfatnom puferu pH 7,50 radi određivanja H ₂O₂ . Pd-MWCNT-SPCE i Pd-MWCNT/SPCE su se pokazale&nbsp; pogodnim&nbsp; za&nbsp; određivanje&nbsp; H ₂O₂ na&nbsp; radnim&nbsp; potencijalima&nbsp; između&nbsp; -0,50&nbsp; i&nbsp; 0,50&nbsp; V,&nbsp; a&nbsp; PtMWCNT-SPCE na ispitivanim radnim potencijalima od -0,80 do 0,70 V. Ove&nbsp; elektrode su zatim modifikovane&nbsp; enzimom&nbsp; glukoza&nbsp; oksidazom&nbsp; (GOx)&nbsp; metodom&nbsp; nano&scaron;enja&nbsp; kapi&nbsp; rastvora&nbsp; GOx&nbsp; i Nafion &reg; -a&nbsp; na&nbsp; njihovu&nbsp; povr&scaron;inu,&nbsp; pri&nbsp; čemu&nbsp; je&nbsp; optimizovana&nbsp; količina&nbsp; nanetog&nbsp; biofilma.&nbsp; GOx/PdMWCNT-SPCE&nbsp; je&nbsp; pokazala&nbsp; bolje&nbsp; analitičke&nbsp; performanse&nbsp; za&nbsp; određivanje&nbsp; glukoze&nbsp; u&nbsp; poređenju&nbsp; sa GOx/Pd- WCNT/SPCE.&nbsp; Kao&nbsp; optimalan&nbsp; radni&nbsp; potencijal&nbsp; GOx/Pd-MWCNT-SPCE&nbsp; je&nbsp; odabrana<br />vrednost&nbsp; potencijala&nbsp; -0,40&nbsp; V&nbsp; u&nbsp; odnosu&nbsp; na&nbsp; ZKE,&nbsp; sa&nbsp; zadovoljavajućom&nbsp; linearno&scaron;ću&nbsp; u&nbsp; ispitivanom opsegu&nbsp; koncentracija&nbsp; glukoze&nbsp; od&nbsp; 0,16&nbsp; do&nbsp; 0,97&nbsp; mmol&nbsp; L -1 (od&nbsp; 29,1&nbsp; do&nbsp; 174&nbsp; &micro;g&nbsp; mL -1),&nbsp; dok&nbsp; je&nbsp; GO iznosila 0,14 mmol L -1 (25 &micro;g mL<br />-1 ). Optimizovana metoda zasnovana na GOx/Pd-MWCNT-SPCE je&nbsp; uspe&scaron;no&nbsp; primenjena&nbsp; za&nbsp; određivanje&nbsp; glukoze&nbsp; u&nbsp; uzorku&nbsp; livadskog&nbsp; meda.&nbsp; Dobijeni&nbsp; rezultati&nbsp; su&nbsp; u dobroj&nbsp; saglasnosti&nbsp; sa&nbsp; onima&nbsp; dobijenim&nbsp; primenom&nbsp; komercijalno&nbsp; dostupnog&nbsp; aparata&nbsp; za&nbsp; merenje glukoze. Pogodan radni potencijal za GOx/Pt-MWCNT-SPCE je bio -0,50 V u odnosu na ZKE, pri čemu je zadovoljavajuća linearnost postignuta u ispitivanom opsegu koncentracija glukoze od 65,8 do 260,6 &micro;g mL -1 , sa GO 35 &micro;g mL -1 . Optimizovana metoda zasnovana na GOx/Pt-MWCNT-SPCE je&nbsp; uspe&scaron;no&nbsp; primenjena&nbsp; za&nbsp; određivanje&nbsp; glukoze&nbsp; u&nbsp; u&nbsp; uzorku&nbsp; belog&nbsp; grožđa&nbsp; i&nbsp; uzorku&nbsp; tableta (Traubenzucker-bonbons),&nbsp; pri&nbsp; čemu&nbsp; su&nbsp; dobijeni&nbsp; rezultati&nbsp; u&nbsp; dobroj&nbsp; saglasnosti&nbsp; sa&nbsp; rezultatima dobijenim primenom Accu-Chek aparata.<br />Na&nbsp; osnovu&nbsp; dobijenih&nbsp; rezultata&nbsp; može&nbsp; se&nbsp; zaključiti&nbsp; da&nbsp; su&nbsp; razvijene&nbsp; analitičke&nbsp; metode&nbsp; pre svega jednostavne, pouzdane i pogodne za dobijanje brzih informacija o sadržaju H ₂O₂ u različitim tipovima&nbsp; uzoraka.&nbsp; Svakako&nbsp; odabir&nbsp; pogodne&nbsp; radne&nbsp; elektrode,&nbsp; kao&nbsp; i&nbsp; optimizacija&nbsp; eksperimentalnih uslova su ključni faktori za uspe&scaron;no određivanje H ₂O₂</p> / null / <p>The aim of this doctoral dissertation was the development of fast and reliable voltammetric methods&nbsp; based&nbsp; on&nbsp; the&nbsp; application&nbsp; of&nbsp; simple&nbsp; and&nbsp; contemporary&nbsp; electrodes/sensors&nbsp; based&nbsp; on carbonaceous materials (carbon paste made of graphite powder and paraffin oil and screen printed carbon electrodes) for the determination of H <span id="cke_bm_571S" style="display: none;">&nbsp;</span>₂<span id="cke_bm_571E" style="display: none;">&nbsp;</span>O₂ in the selected complex model and real samples.For this purpose, applicability of different working electrodes was investigated.The&nbsp; amperometric&nbsp; method&nbsp; based&nbsp; on&nbsp; carbon&nbsp; paste&nbsp; electrode&nbsp; (CPE)&nbsp; bulk- modified&nbsp; &nbsp;&nbsp; with 5% (m:m) MnO 2 , under optimized conditions, with a working potential of 0.40 V vs. the saturated calomel&nbsp; elect<span id="cke_bm_572E" style="display: none;">&nbsp;</span>rode&nbsp; (SCE)&nbsp; and&nbsp; a&nbsp; phosphate&nbsp; buffer&nbsp; solution&nbsp; (pH&nbsp; 7.50)&nbsp; as&nbsp; supporting&nbsp; electrolyte, enabled the quantitation of H <span id="cke_bm_577S" style="display: none;">&nbsp;</span>₂<span id="cke_bm_577E" style="display: none;">&nbsp;</span>O₂in the concentration interval from 1.4 to 65 &micro;g mL &minus;1 with a relative standard deviation (RSD) of less than 10%. This meth<span id="cke_bm_578E" style="display: none;">&nbsp;</span>od was applied for the determination of the H<span id="cke_bm_583S" style="display: none;">&nbsp;</span>₂<span id="cke_bm_583E" style="display: none;">&nbsp;</span>O₂consumption&nbsp; in&nbsp; samples&nbsp; of&nbsp; groundwater&nbsp; fro<span id="cke_bm_584E" style="display: none;">&nbsp;</span>m&nbsp; the&nbsp; Central&nbsp; Banat&nbsp; region&nbsp; (Province&nbsp; of Vojvodina, Serbia) treated by the Fenton (Fe ²⁺and H ₂O₂ ) and Fenton-&nbsp; like (Fe ³⁺and H ₂O₂ ) reagents to remove natural organic matter (NOM) at&nbsp; differentinitial concentrations of iron species, and of their molar ratios to the initial concentration of H₂O₂ . It was found that the form of Fe (Fe ²⁺ or Fe ³⁺ )and the molar&nbsp; ratio to H ₂O₂influenced the degree of the H₂O₂ decomposition in the groundwater with high NOM content. Besides, in the case of the Fenton-like process, for all initial doses of Fe ³⁺ and H<span id="cke_bm_604S" style="display: none;">&nbsp;</span>₂<span id="cke_bm_604E" style="display: none;">&nbsp;</span>O₂, a sign<span id="cke_bm_605E" style="display: none;">&nbsp;</span>ificant amount of H<span id="cke_bm_610S" style="display: none;">&nbsp;</span>₂<span id="cke_bm_610E" style="display: none;">&nbsp;</span>O₂ remained unused, whi<span id="cke_bm_611E" style="display: none;">&nbsp;</span>ch also indicates a lower efficiency of such system compared to the Fenton process. Screen&nbsp; printed&nbsp; carbon&nbsp; electrode&nbsp; (SPCE)&nbsp; bulk-modified&nbsp; with&nbsp; MnO&nbsp;₂ as&nbsp; a&nbsp; mediator&nbsp; was applied&nbsp; for&nbsp; amperometric&nbsp; determination&nbsp; of&nbsp; the&nbsp; H <span id="cke_bm_617S" style="display: none;">&nbsp;</span>₂<span id="cke_bm_617E" style="display: none;">&nbsp;</span>O₂ content&nbsp; during&nbsp; the&nbsp; Fenton&nbsp; (Fe ²⁺ ,&nbsp; H <span id="cke_bm_624S" style="display: none;">&nbsp;</span>₂<span id="cke_bm_624E" style="display: none;">&nbsp;</span>O₂)&nbsp; and <span id="cke_bm_625E" style="display: none;">&nbsp;</span>visible&nbsp; light-assisted<span id="cke_bm_618E" style="display: none;">&nbsp;</span>,&nbsp; photo-Fenton&nbsp; (Fe ^2+&nbsp; ,&nbsp; H <span id="cke_bm_631S" style="display: none;">&nbsp;</span>₂<span id="cke_bm_631E" style="display: none;">&nbsp;</span>O₂ ,&nbsp; h&nu;)<span id="cke_bm_632E" style="display: none;">&nbsp;</span>&nbsp; based&nbsp; removal&nbsp; of&nbsp; neonicotinoid&nbsp; insecticide acetamiprid (ACT). Under&nbsp; optimized conditions (working potential of 0.40 V vs. SCE, phosphate buffer&nbsp; pH&nbsp; 7.50&nbsp; as&nbsp; supporting&nbsp; electrolyte)&nbsp; amperometric&nbsp; determination&nbsp; of&nbsp; H <span id="cke_bm_637S" style="display: none;">&nbsp;</span>₂<span id="cke_bm_637E" style="display: none;">&nbsp;</span>O₂showed&nbsp; a&nbsp; linear dynamic range from 0.01 to 1.24 mmol L -1 (from 0.34 to 42.2 &micro;g mL -1) and the RSD did not exceed 4.2%. In the investigated samples (after appropriate pH adjustment from 2.8 to 7.5 instantly after the sampling<span id="cke_bm_638E" style="display: none;">&nbsp;</span> to stop or maximum decelerate the oxidation processes, filtering, and storage of the deep- frozen sample with defrosting immediately before the measurements) the H <span id="cke_bm_643S" style="display: none;">&nbsp;</span>₂<span id="cke_bm_643E" style="display: none;">&nbsp;</span>O₂&nbsp; contents were determined by the standard addition method by analyzing the corresponding amperometric curves. Parallel HPLC-DAD measurements were performed to monito<span id="cke_bm_644E" style="display: none;">&nbsp;</span>r the concentration/removal of ACT. In the case of the photo- Fenton process (initial concentrations: 0.31; 2.0 and 3.0 mmol L -1 (70.0; 111.7 and 102.1 &micro;g mL -1 ) of ACT, Fe²⁺ and H <span id="cke_bm_650S" style="display: none;">&nbsp;</span>₂<span id="cke_bm_650E" style="display: none;">&nbsp;</span>O₂, respec<span id="cke_bm_651E" style="display: none;">&nbsp;</span>tively) after 10 min of irradiation H <span id="cke_bm_656S" style="display: none;">&nbsp;</span>₂<span id="cke_bm_656E" style="display: none;">&nbsp;</span>O₂ was&nbsp; consumed&nbsp; and&nbsp; it&nbsp; can&nbsp; be&nbsp; consi<span id="cke_bm_657E" style="display: none;">&nbsp;</span>dered&nbsp; that&nbsp; ACT&nbsp; was&nbsp; removed&nbsp; after&nbsp; 5&nbsp; min.&nbsp; During&nbsp; the&nbsp; Fenton process ACT was removed after 20 min of treatment and around 10% of the initial concentration of the H 2O2 remained still unused.<br />CPE&nbsp; was&nbsp; surface&nbsp; modified&nbsp; with&nbsp; a&nbsp; composite&nbsp; of&nbsp; Pt&nbsp; nanoparticles&nbsp; (&lt;&nbsp; 5&nbsp; nm)&nbsp; on&nbsp; graphitized carbon (Pt-C, 10% Pt on Vulcan XC72) by simply dropcoating method. The unmodified CPE and the&nbsp; modified&nbsp; one&nbsp; (Pt-C/CPE)&nbsp; were&nbsp; characterized&nbsp; by&nbsp;&nbsp; EM/EDS&nbsp; and&nbsp; CV&nbsp; measurements.&nbsp; The&nbsp; PtC/CPE showed remarkable electrocatalytic propertiestoward the electrochemical redox reaction of H<span id="cke_bm_662S" style="display: none;">&nbsp;</span>₂<span id="cke_bm_662E" style="display: none;">&nbsp;</span>O₂ compared to&nbsp; modified CPE in phosphate buffer (0.1 mol L -1 ; pH 7.50), as well in acetatebuffer&nbsp; (0.1 mol&nbsp; L -1 ; pH .50) supporting&nbsp; electrolytes. Amperometry of&nbsp; H2O2 in the concentration range from 0.15 to 1.45 &micro;g mL -1 with the Pt-C/CPE showed acceptable linearity, while the obtained values of LOQs were 0.06 &micro;g mL -1&nbsp; (pH 7.50, working potential 0.20 V) and 0.10 &micro;g mL -1 (pH 4<span id="cke_bm_663E" style="display: none;">&nbsp;</span>.50, working potential 0.50 V). The proposed analytical&nbsp; methods were applied to the determination of the H 2O2 content in commercially available personal care products; i.e., disinfection (pH 7.50) and contact lens cleaning solutions (pH 4.50). The obtained amperometric results are in good agreement with those measured by traditional titanium sulfatereagent based spectrophotometric method with determined concentrations as 2.91% and 2.94%&nbsp; for the disinfection product, and 3.04% and 3.17% for the contact lens solution, respectively. RSD was lower than 2%. The obtained results are in a good agreement with the amounts of the H<span id="cke_bm_668S" style="display: none;">&nbsp;</span>₂<span id="cke_bm_668E" style="display: none;">&nbsp;</span>O₂declared by producers (3%) in the both investigated samples. The Pt-C/CPE was also tested for monitoring of the H<span id="cke_bm_674S" style="display: none;">&nbsp;</span>₂<span id="cke_bm_674E" style="display: none;">&nbsp;</span>O₂ residual concentration in contact lens&nbsp; solution&nbsp; during&nbsp; its&nbsp; neutralization/decomposition&nbsp; rocess.&nbsp; At&nbsp; 6&nbsp; h&nbsp; of<span id="cke_bm_675E" style="display: none;">&nbsp;</span>&nbsp; neutralization&nbsp; treatment 24.68 &micro;g mL -1 of the H <span id="cke_bm_680S" style="display: none;">&nbsp;</span>₂<span id="cke_bm_680E" style="display: none;">&nbsp;</span>O₂was&nbsp; determined which is almost half of the allowedH2<span id="cke_bm_681E" style="display: none;">&nbsp;</span>O2 concentration in the case of the contact lens solution concerningthe limit of eye irritation. CPE&nbsp; was&nbsp; surface&nbsp;&nbsp; modified&nbsp; with&nbsp; multiwalled&nbsp; carbon&nbsp; nanotubes&nbsp; (MWCNT)&nbsp; and&nbsp; with composites of MnO₂-MWCNT or Pt-MWCNT by drop coating method to prepare simply, sensitive and reliable volta<span id="cke_bm_669E" style="display: none;">&nbsp;</span>mmetric sensors for the determination of H <span id="cke_bm_687S" style="display: none;">&nbsp;</span>₂<span id="cke_bm_687E" style="display: none;">&nbsp;</span>O₂in selected sample. The results of the&nbsp; SEM/<span id="cke_bm_688E" style="display: none;">&nbsp;</span>EDS&nbsp; analysis&nbsp; of&nbsp; composite&nbsp; materials&nbsp; have&nbsp; confirmed&nbsp; that&nbsp; the&nbsp; mediators,&nbsp; MnO ₂ and&nbsp; Pt&nbsp; articles, are randomly distributed on the surface of MWCNT and represent nearly 5% (m:m) of the composite expressed as Mn and Pt. CV measurements were performed&nbsp; with prepared electrodes in acetate&nbsp; (pH&nbsp; 4.50),&nbsp; phosphate&nbsp; (pH&nbsp; 7.50)&nbsp; and&nbsp; borate&nbsp; (pH&nbsp; 9.18)&nbsp; buffers&nbsp; to&nbsp; characterize&nbsp; the&nbsp; basic electrochemical&nbsp; behavior&nbsp; of&nbsp; H <span id="cke_bm_694S" style="display: none;">&nbsp;</span>₂<span id="cke_bm_694E" style="display: none;">&nbsp;</span>O₂ and&nbsp; to&nbsp; select&nbsp; the&nbsp; working&nbsp; potentials&nbsp; suitable&nbsp; for&nbsp; amperometric determination&nbsp; of&nbsp; this&nbsp; target&nbsp; analyte.&nbsp; The&nbsp; Pt-MWCNT/CPE&nbsp; performs&nbsp; well&nbsp; in&nbsp; phosphate&nbsp; buffer pH .50 and acetate buffer solution pH 4.50 in the&nbsp; negative as well as in the positive polarization range with RSD mainly lower than 2.5%. In case of MnO₂-MWCNT/CPE at <span id="cke_bm_695E" style="display: none;">&nbsp;</span>0.30 V and above the H<span id="cke_bm_701S" style="display: none;">&nbsp;</span>₂<span id="cke_bm_701E" style="display: none;">&nbsp;</span>O₂oxidation signal is rem<span id="cke_bm_702E" style="display: none;">&nbsp;</span>arkable in slightly alkaline media (pH 7.50), at pH 4.50 this electrode showed poor behavior and at pH 9.18 offered acceptable performance. LOQs were in the &micro;g mL -1 concentration&nbsp; range.&nbsp; H<span id="cke_bm_707S" style="display: none;">&nbsp;</span>₂<span id="cke_bm_707E" style="display: none;">&nbsp;</span>O₂was&nbsp; determined&nbsp; in&nbsp; a&nbsp; spiked&nbsp; milk&nbsp; sample&nbsp; by&nbsp; standard addition&nbsp; method after&nbsp; appropriate&nbsp; sample&nbsp; preparation&nbsp; (pH&nbsp; adjustment and&nbsp; centrifugation)&nbsp; and&nbsp; using&nbsp; optimized amperometric p<span id="cke_bm_708E" style="display: none;">&nbsp;</span>rocedure (acetate buffer pH 4.50, working potential -0.75 V) by Pt-MWCNT/CPE as a working electrode. RSD for three repeated measurements was 2.5%, while the recovery of the method was a bit higher than 71%. The&nbsp; composite&nbsp; materials&nbsp; consisting&nbsp; of&nbsp; MWCNT&nbsp; and&nbsp; Pd&nbsp; (Pd-MWCNT)&nbsp; or&nbsp; Pt&nbsp; containing particles&nbsp; (Pt-WCNT)&nbsp; were&nbsp; applied&nbsp; to&nbsp; the&nbsp; preparation&nbsp; of&nbsp; bulk- modified&nbsp; SPCEs&nbsp; (Pd-MWCNTSPCE and Pt-MWCNT-SPCE) and surface modifiedSPCE (Pd- MWCNT/SPCE). These electrodes, as well as unmodified SPCE and MWCNT-SPCE,&nbsp; were characterized by CV and&nbsp; amperometry&nbsp; in phosphate&nbsp; buffer&nbsp; solution&nbsp; of&nbsp; pH&nbsp; 7.50&nbsp; for&nbsp; the&nbsp; H<span id="cke_bm_713S" style="display: none;">&nbsp;</span>₂<span id="cke_bm_713E" style="display: none;">&nbsp;</span>O₂determination.&nbsp; Pd-MWCNT-SPCE&nbsp; and&nbsp; PdMWCNT/SPCEare convenient for the etermination of H 2O2 at working potentials from -0.50 to 0.50 V, and Pt-MWCNT-SPCE at investigated working potentials in the range from -0.80 to 0.70 V. These electrodes were then modified with glucose&nbsp; oxidase (GOx) by drop coating a solution of GOxand Nafion &reg; on their surface, whereby the applied amount of biococktail was optimized. GOx/PdMWCNT-SPCE&nbsp; showed&nbsp; better&nbsp; analytical&nbsp; performance&nbsp; for&nbsp; glucose&nbsp; determination&nbsp; in&nbsp; comparison with&nbsp; GOx/Pd-MWCNT/SPCE.&nbsp; The&nbsp; optimal&nbsp; working&nbsp; potential&nbsp; for&nbsp; GOx/Pd-MWCNT- SPCE&nbsp; was -0.40 V vs. SCE and <span id="cke_bm_714E" style="display: none;">&nbsp;</span>satisfactory linearity was obtained in the investigated glucose concentration range from 0.16 to 0.97 mmol L -1 (from 29.1 to 174&nbsp; &micro;g mL -1 ), hile the LOQ was 0.14 mmol L -1 (25 &micro;g mL -1 ). The optimized method based on GOx/Pd-MWCNT-SPCE was successfully applied to the determination of glucose in multifloral honey sample.&nbsp; The results are in a good agreement with those&nbsp; obtained by commercially available equipment for determination of glucose. Optimal working potential&nbsp; for&nbsp; GOx/Pt-MWCNT-SPCE&nbsp; was&nbsp; -0.50&nbsp; V&nbsp; vs.&nbsp; SCE,&nbsp; and&nbsp; the&nbsp;&nbsp; satisfactory&nbsp; linearity&nbsp; was obtained in the investigated concentration range ofglucose from 65.8 to 260.6&nbsp; &micro;g mL -1 , with LOQ of 35&nbsp; &micro;g mL -1 . The optimized method based on GOx/Pt- MWCNT-SPCE was successfully applied for determination of glucose in white grape and glucose tablets (Traubenzucker-bonbons) samples, whereby&nbsp; the&nbsp; obtained&nbsp; results&nbsp; were&nbsp; in&nbsp; a&nbsp; good&nbsp; agreement&nbsp; with&nbsp; the&nbsp; results&nbsp; obtained&nbsp; by&nbsp; Accu-Chek device. Based on the results, the developed analytical methods are first of all simple, reliable and suitable&nbsp; for&nbsp; obtaining&nbsp; fast&nbsp; information&nbsp; about&nbsp; the&nbsp; content&nbsp; of&nbsp; H ₂O₂ in&nbsp; different&nbsp; types&nbsp; of&nbsp; samples. Certainly the selection of a suitable working electrode, as well as the optimization of experimental conditions are key factors for the successful determination of H₂O₂.</p>