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31	Synthesis and investigation of nanostructured polymer composites based on heterocyclic esters and carbon nanotubes / Synthèse et caractérisation de composites polymères nanostructurés à base d’esters hétérocycliques chargés de nanotubes de carbone Bardash, Liubov 28 September 2011 (has links) La thèse concerne les synthèse et caractérisation de composites polymères nanostructurés à base d’esters de cyanates de bisphénol a (DCBA) ou à base d’oligomères cycliques de butylène téréphtalate (CBT) et de nanotubes de carbone multi-parois (MWCNTS). L’effet catalytique des nanotubes de carbone sur la polycyclotrimerisation de DCBA et aussi sur la polymérisation du CBT est observé. L’augmentation de la température de cristallisation a été fixée pour tous les échantillons de nanocomposites à base de polybutylène téréphtalate (cPBT). L’effet de la méthode de mise en forme de cPBT/MWCNTS sur ses propriétés thermiques et électriques a été établi. Il est observé que le traitement thermique additionnel des échantillons (recuit) à des températures inférieures à celle de la fusion du cPBT cause la réagglomération des MWCNTS dans le système. Il est établi que l’ajout de très bas taux de MWCNTS (0.03-0.06 pour cent en masse) dans la matrice de polycyanurate (PCN) augmente les valeurs de résistance à la flexion (64-94 pour cent). De même l’ajout de 0.01 pourcent de MWCNTS en masse dans le CBT augmente considérablement le module d'élasticité des nanocomposites cPBT. Cet effet a été expliqué par la dispersion efficace de cette faible quantité de nanocharges pendant la synthèse in situ de la matrice de cPBT et est confirmée par les clichés en microscopie. Il est déterminé que les propriétés électriques des nanocomposites à base d’esters hétérocycliques et MWCNTS peuvent varier de matériaux isolants aux matériaux conducteurs. Les seuils de percolation des deux systèmes sont très bas (0.22 et 0.38 pourcent pour nanocomposites à base de cPBT et PCN respectivement). La conductivité des composites conducteurs est particulièrement stable sur un large domaine de température ce qui laisse présager des applications intéressantes dans le domaine de la microélectronique et pour des pièces d’avion et de navettes spatiales. / The thesis relates to synthesis and investigation of nanostructured polymer composites based on oligomers of cyanate esters of bisphenol a (DCBA) or cyclic butylene terephthalate (CBT) and multiwalled carbon nanotubes (MWCNTS). Catalytic effect of mwcnts in process of DCBA polycyclotrimerization as well as in cbt polymerization has been observed. Significant increase in crystallization temperature of nanocomposites based on polybutylene terephthalate (cPBT) with adding of MWCNTS is observed. The effect of processing method of cpbt/mwcnts nanocomposites on its electrical properties has been found. It has been established that the additional heating of the samples (annealing) at temperatures above melting of cPBT leads to reagglomeration of MWCNTS in the system. It is established that reagglomeration of MWCNTS results in increase of conductivity values of nanocomposites due to formation of percolation pathways of MWCNTS through polymer matrix. In the case of polycyanurate matrix (PCN), it is found that addition of small mwcnts contents (0.03-0.06 weight percents) provides increasing tensile strength by 62-94 percents. It has been found that addition of even 0.01 weight percents of MWCNTS provides significant increase in storage modulus of cPBT matrix. This is explained by effective dispersing of small amount of the nanofiller during in situ synthesis of pcn or cpbt matrix that is confirmed by microscopy techniques. It has been established that the properties of the nanocomposites based on heterocyclic esters and MWCNTS can be varied from isolator to conductor and has low percolation thresholds (0.22 and 0.38 weight percents for cPBT and PCN nanocomposites respectively). The conductivity of samples is particularly stable on a very large range of temperature from 300 to 10 degrees Kelvin that make these materials perspective for practical applications in microelectronics, as parts of aircraft and space constructions. Polymères nanocomposites Nanotubes de carbone multi-paroi Esters de cyanates Synthèse in situ Effet catalytique Propriétés mécaniques Propriétés électriques Nanocomposite polymer Multiwalled carbon nanotubes Cyanate esters Cyclic butylene terephtalate In situ synthesis Catalytic effect Mechanical properties Electrical properties 620.1
32	Direkter Drucksensor unter Verwendung von Kohlenstoffnanoröhren-Nanokompositen / Direct pressure sensor using carbon nanotubes nanocomposite Dinh, Nghia Trong 08 July 2016 (has links) (PDF) Im Gegensatz zu herkömmlichen Dehnungsmessstreifen können Carbon nanotube (CNT)-basierte Komposite zusätzlich eine ausgeprägte Druck-abhängigkeit des Widerstandes aufweisen. Deshalb können Drucksensoren aus CNT-Nanokomposite ohne den Einsatz von Verformungskörpern wie z. B. Biegebalken aufgebaut werden. Die möglichen Anwendungsgebiete für diese direkt messenden Sensoren wurden in der vorliegenden Arbeit bei drei industriellen Anwendungen wie z. B. bei Robotergreifarmen gezeigt. Die Zielstellung dieser Arbeit ist die Entwicklung und Charakterisierung eines neuartigen Sensors aus CNT-Nanokomposite. Unter Verwendung von Multi-walled carbon nanotube (MWCNT)-Epoxidharz und interdigitalen Elektroden soll der Sensor auf wenigen Quadratzentimetern Drücke im Megapascal-Bereich und somit Kräfte im Kilonewton-Bereich messen können. Durch die Auswahl geeigneter Werkstoffe und die Modellierung mit der Finite Element Methode wurde der Sensorentwurf durchgeführt sowie der Messbereich abgeschätzt. Die Herstellung der MWCNT-Epoxidharz-Dispersion erfolgte durch mechanische Mischverfahren. Anschließend wurden aus der Dispersion druckempfindliche Schichten mit der Schablonendrucktechnik hergestellt. Dabei wurden die Herstellungs-parameter und besonders der Füllstoffgehalt der MWCNTs variiert, um deren Einflüsse auf das mechanische, thermische und elektrische Verhalten zu untersuchen. Die Charakterisierung der mechanischen Kenngrößen erfolgte mit Zugversuchen und dynamisch-mechanischer Analyse. In den Untersuchungen zeigen die MWCNT-Komposite eine signifikante Steigerung der Zugfestigkeit und eine Erhöhung der Glasübergangstemperatur gegenüber reinem Epoxidharz. Die Abhängigkeiten der Druckempfindlichkeit und der Temperaturempfindlichkeit vom Füllstoffgehalt wurden untersucht. Eine besonders hohe Druckempfindlichkeit, aber auch Temperaturempfind-lichkeit wurde bei Proben mit geringem Füllstoffgehalt (1 wt% und 1,25 wt%) festgestellt. Es ist also wichtig, die richtige Materialkombination für diese Art Sensor zu finden. Die realisierten Sensoren liefern zuverlässige Antwortsignale bei wiederholten Belastungen bis zu einer Belastung von 20 MPa (entspricht 2 kN). Zusätzlich wurde der Temperatureinfluss in einem Bereich von −20 °C bis 50 °C durch eine Wheatstonesche Brückenschaltung kompensiert. Die vorliegende Arbeit zeigt, dass eine zuverlässige Druckmessung mit einer Temperaturmessabweichung von 0,214 MPa/10 K gewährleistet werden kann. / In contrast to conventional metallic strain gauges, carbon nanotube (CNT) composites have an additional pressure sensitivity. Therefore, deformation elements such as bending beam is not needed by using pressure sensors, which are based on CNT nanocomposite. The possible areas of application for these pressure direct measured sensors were showed in three industrial application such as robot gripper. The focus of this work is the development and characterization of a new sensor manufactured from CNT nanocomposite. By using multi-walled carbon nanotube (MWCNT) epoxy and interdigital electrodes the sensor, which has a dimension of few square centimetre, should measure a pressure in mega Pascal range and hence a force in kilo newton range. By the selection of suitable materials and the modelling using finite element method, the sensor design as well as the measurement range were carried out. The MWCNT epoxy dispersion is manufactured by using a mechanical mixing process. Subsequent, the dispersion is used to fabricate pressure sensitive layers by stencil printing methods. Thereby, the fabrication parameters and especially the filler content of the MWCNTs were varied for the mechanical, thermal and electrical investigation. The characterization of the mechanical characteristic values were carried out by using tensile test and dynamic mechanical analysis. The results show a significant increasing of the tensile strength and glass transition temperature in comparison to neat epoxy. Additionally, the influence of the filler content to the pressure and thermal sensitivity were investigated. A highly pressure sensitivity but also a highly thermal sensitivity are obtained for samples with lower filler contents (1 wt% and 1.25 wt%). Therefore, a suitable material combination has to be chosen. The fabricated sensors show reliable response signals by repeated excitations up to 20 MPa (meets to 2 KN). Moreover, the temperature influence ranged from -20 °C to 50 °C was compensated with a Wheatstone bridge. This work demonstrate a direct pressure sensitive sensor with reliable response signals by a thermal deviation of 0.214 MPa/10K. ddc:600 ddc:607 ddc:500 ddc:537 ddc:542
33	Optimizacija metoda ekstrackcije i određivanja neonikotinoida tečnom hromatografijom u odabranim uzorcima / Optimization of extraction and determination of neonicotinoids using liquid chromatography in selected samples Jovanov Pavle 01 July 2014 (has links) <p>Insekticidi novije generacije, neonikotinoidi, odlikuju se specifičnim načinom  delovanja na nervni sistem insekata. Radi dobijanja &scaron;to brže i kvalitetnije informacije o izloženosti životne sredine ovim insekticidima i količinama njihovih ostataka u hrani potrebno je raspolagati odgovarajućim instrumentalnim metodama za njihovo određivanje. Razvijene su i optimizovane analitičke metode zasnovane na tečnoj hromatografiji za određivanje sedam odabranih neonikotinoida (dinotefurana, nitenpirama, tiametoksama, klotianidina, imidakloprida, acetamiprida  i tiakloprida) u medu i likeru od meda. Ispitivana je mogućnost određivanja klotianidina pomoću tečne hromatografije visoke efikasnosti sa detektrorom od niza dioda (HPLC-DAD) primenom kombinacije tečno-tečne i ekstrakcije na čvrstoj fazi iz uzoraka meda. Na osnovu preliminarnih rezultata može se zaključiti da kori&scaron;ćenje  faznih-čvrsto kolona u kombinaciji sa tečno-tečnom ekstrakcijom dihlormetanom rezultira prihvatljivim prinosom klotianidina u uzorcima meda pri koncentraciji od oko 0,5 µg g<sup>-1 </sup>klotianidina. Radi dobijanja većih prinosa odabrana je disperzna tečno-tečna mikroekstrakcija (DLLME) kao tehnika pripreme uzoraka meda. Testirana je upotreba acetonitrila kao disperznog sredstva. Pored hloroforma, kori&scaron;ćen je i dihlormetan kao drugo ekstrakciono sredstvo, kako bi se  uporedila efikasnost ekstrakcije. Zabeleženi su prinosi klotianidina od 69,7 i 68,3%  u zavisnosti da li je kori&scaron;ćen hloroform, odnosno DHM kao rastvor za ekstrakciju. Može se zaključiti da je prinos ekstrakcije bio povoljniji pri odnosu 0,5 mL ACN i 2,0 mL DHM. Prinosi su se kretali od 68,4% do 92,1%, &scaron;to je ukazalo da su parametri DLLME ekstrakcije optimalni. Kako bi se detaljnije ispitali ključni parametri DLLME tehnike, kori&scaron;ćena je metodologija povr&scaron;ine odziva (RSM), kao i detekcija na osetljivijem kuplovanom masenom detektoru (MS/MS). Optimizovani su HPLC-MS/MS  parametri kako bi se obezbedilo zadovoljavajuće hromatografsko  razdvajanje i niske granice detekcije (GD, 0,5–1,0 μg kg<sup>-1</sup>) i određivanja (GO, 1,0–2,5 μg kg<sup>-1</sup>) ispitivanih neonikotinoida u medu. Upotrebom centralno kompozitnog dizajna konstruisani su kvadratni modeli ispitivanih faktora: zapremine ekstrakcionog (DHM, 1,0–3,0 mL) i disperznog (ACN, 0,0–1,0 mL) sredstva, izračunati statistički parametri i optimizovan proces DLLME upotrebom <em>Derringer</em>-ove funkcije poželjnih odgovora. Upotrebom MMC i SC krivih u opsegu GO–100,0 μg kg<sup>-1 </sup>ispitan je uticaj matriksa pri čemu zaključeno je da je najveći uticaj matriksa bio na odziv analitičkog signala nitenpirama, dinotefurana i klotianidina. Ispitani su prinosi odabranih neonikotinoida (R, 74,3–113,9%), kao i preciznost metode u uslovima ponovljivosti (RSD, 2,74– 11,8%) i intermedijerne reproduktivnosti (RSD, 6,64–16,2%). Brza (retenciona vremena 1,5–9,9 min) i osetljiva metoda, koja tro&scaron;i malu količinu rastvarača, primenjena je za ispitivanje 15 realnih uzoraka meda različitog cvetnog porekla. Rezultati su pokazali da ispitivani med nije sadržao ostatke ispitivanih neonikotinoida u koncentracijama iznad GD. Dalje istraživanje je bilo usmereno ka  razvijanju i optimizaciji HPLC-DAD analitičke metode upotrebom DLLME i QuEChERS tehnika za  pripremu uzoraka za određivanje 7 neonikotinoida u uzorcima meda. U ovom delu istraživanja optimizovani su i hromatografski parametri, upotrebom RSM sa Box-Behnken-ovim dizajnom i Derringer-ovom funkcijom poželjnih odgovora. Od  ispitivanih neonikotinoida dinotefuran i imidakloprid su bili u najvećoj meri izloženi uticaju matriksa, bez obzira na proceduru pripreme uzoraka. Može se istaći da je uticaj matriksa na analitički signal dinotefurana bio izraženiji u slučaju MS/MS, apostrofirajući manju robusnost ove metode određivanja. Prinosi neonikotinoida su  bili (R, 73,1–118,3%), preciznost u uslovima ponovljivosti (RSD, 3,28–10,40%) i intermedijerne reproduktivnosti (RSD, 6,45–17,70%), a granice detekcije (GD, 1,5–2,5 µg kg<sup>-1</sup>) i određivanja (GO, 5,0–10,0 µg kg<sup>-1</sup>). Metoda je primenjena za ispitivanje 7 neonikotinoida u 104 uzorkameda različitog cvetnog porekla sa  teritorije Autonomne Pokrajine Vojvodine. Detektovano je prisustvo tiakloprida, imidakloprida i tiametoksama u količinama koje su bile ispod MDK RS i EU. Analizirani su uzorci likera od meda - medice. Upoređivane su dve tehnike pripreme uzoraka, DLLME i QuEChERS i primenjeni optimizovani hromatografski  uslovi i MS/MS parametri. U slučaju nitenpirama, dinotefurana i tiametoksama uticaj matriksa bio je najizraženiji. Metoda je validovana određivanjem prinosa neonikotinoida (R, 69,2–113,4%), preciznosti u uslovima ponovljivosti (RSD, 3,21–12,81%) i intermedijerne reproduktivnosti (RSD, 9,11–16,63%), kao i granice detekcije (GD, 0,5–2,5 µg kg<sup>-1</sup>) i određivanja (GO, 1,0–10,0 µg kg<sup>-1</sup>). Analizom 10 komercijalno dostupnih likera od meda otkriveno je prisustvo klotianidina i tiakloprida, evčzokinot&scaron; z  na neophodnost daljeg kontrolisanja ovog proizvoda na prisustvo neonikotinoida. Ispitana je mogućnost uklanjanja odabranih neonikotinoida (dinotefurana, klotianidina i tiakloprida) iz vodene sredine (reke Dunav). Ispitivanje efikasnosti 6 različitih vrsta uklanjanja odabranih neonikotinoida (u prisustvu prirodne insolacije u laboratorijskim uslovima, sa dodatkom H2O2, sa dodatkom MWCNT, sa dodatkom MWCN+H <sub>2</sub>O<sub>2</sub>, sa dodatkom Fe-MWCNT, sa dodatkom Fe-MWCNT+H<sub>2</sub>O<sub>2</sub>) vr&scaron;eno je upotrebom prethodno razvijene HPLC-MS/MS metode. Krive uklanjanja odabranih neonikotinoida, pokazale su da tokom 60 minuta pri prirodnoj insolaciji  u laboratorijskim uslovima koncentracija smanjenje oko 25%. Analitički signal dinotefurana dobijen u prisustvu H<sub>2</sub>O<sub>2 </sub>pod istim uslovima ukazuje na uklanjanje ciljnog analita od oko 40%, tiakloprida od oko 70%, a klotianidina u potpunosti. Testirana je adsorpcija ciljnog analita na vi&scaron;ezidnim ugljeničnim nanocevima (MWCNT). Ovim postupkom može da se ukloni oko 30% dinotefurana, oko 50% klotianidina i 60% tiakloprida. U kombinaciji sa H<sub>2</sub>O<sub>2 </sub>, MWCNT pokazuju bolju sposobnost uklanjanja za 15–50% u zavisnosti od ispitivanog neonikotinoida. Upotreba Fe-MWCNT i njihova kombinacija sa H<sub>2</sub>O<sub>2</sub> otvorila je mogućnost za dalja  ispitivanja mehanizma uklanjanja. Ustanovljeno je nastajanje intermedijera kojima odgovaraju m/z od 117,5 i 140,6 u slučaju razgradnje dinotefurana u sistemima sa H<sub>2</sub>O<sub>2</sub>, MWCNT+H<sub>2</sub>O<sub>2</sub>, Fe-MWCNT+H<sub>2</sub>O<sub>2 </sub>i klotianidina u sistemu Fe-MWCNT+H<sub>2</sub>O<sub>2</sub>.</p> / <p>Neonicotinoid insecticides, as one of the fastest growing new generation of insecticides, have contributed to a significant reduction of toxicity for the environment; therefore, monitoring and determination of trace levels of the neonicotinoids in honey are necessary and demands highly efficient, selective and sensitive analytical techniques. The objective of the present work was to develop a rapid, sensitive, optimized and accurate analytical method based on liquid chromatography for determining seven neonicotinoid insecticides, dinotefuran, nitenpyram, thiamethoxam, clothianidin, imidacloprid, acetamiprid and thiacloprid in honey and honey liqueur samples. The possibility for determination of clothianidin in honey samples was investigated by HPLC with a diode array detector (HPLC-DAD). Based on preliminary results, it can be concluded that the use of a solid-phase column in combination with a liquid-liquid extraction with dichloromethane results in an acceptable recovery of clothianidin in the samples with a clothianidin concentration of about 0.5 µg g<sup>-1</sup>. After obtaining low recovery of clothianidin, dispersed liquid-liquid microextraction (DLLME) was selected as a technique for the preparation of honey samples.. The adequacy of acetonitrile as a dispersing agent was investigated. Besides the chloroform, a dichloromethane was used as a second extracting agent , in order to compare the relative efficiency of the extraction solvents. It can be concluded that the extraction recovery (68.4–92.1%) was more favorable with the use of 0.5 mL ACN and 2.0 mL DHM. Furthermore, LC-MS/MS parameters were optimized to unequivocally provide good chromatographic separation, low detection (LOD, 0.5–1.0 μg L<sup>−1</sup>) and quantification (LOQ, 1.0–2.5 μg L<sup>−1</sup>) limits for acetamiprid, clothianidin, thiamethoxam, imidacloprid, dinotefuran, thiacloprid and nitenpyram in honey samples. Using different <br />types (chloroform, dichloromethane) and volumes of extraction (1.0–3.0 mL) and dispersive (acetonitrile; 0.0–1.0 mL) solvent and by mathematical modeling it was possible to establish the optimal sample preparation procedure. Matrix-matched calibration and blank honey sample spiked in the <span style="font-size: 12px;">concentration range of LOQ–100.0 μg kg</span><sup><span style="font-size: 12px;">−1 </span></sup><span style="font-size: 12px;">were used to compensate the matrix effect and to fulfill the </span><span style="font-size: 12px;">requirements of SANCO/12495/2011 for the accuracy (R 74.3–113.9%) and precision (expressed in </span><span style="font-size: 12px;">terms of repeatability (RSD 2.74–11.8%) and within-laboratory reproducibility (RSDs  6.64–16.2%)) of </span><span style="font-size: 12px;">the proposed method. The rapid (retention times 1.5–9.9 min), sensitive and low solvent consumption </span><span style="font-size: 12px;">procedure described in this work provides reliable, simultaneous, and quantitative method applicable for </span><span style="font-size: 12px;">the routine laboratory analysis of seven neonicotinoid residues in 15 real honey samples. Neonicotinoid  </span><span style="font-size: 12px;">residues were not detected in any of the investigated samples. The objective of next study was to </span><span style="font-size: 12px;">develop and optimize HPLC-DAD analytical method with dispersive liquid-liquid microextraction </span><span style="font-size: 12px;">(DLLME) and QuEChERS sample preparation procedures for the simultaneously analysis of seven </span><span style="font-size: 12px;">neonicotinoids in honey samples. The liquid chromatographic conditions were optimized by response </span><span style="font-size: 12px;">surface methodology with <em>Box-Behnken</em> design and the global <em>Derringer</em>´s desirability. The optimized </span><span style="font-size: 12px;">method was  validated to fulfill the requirements of SANCO/12495/2011 standard for both sample </span><span style="font-size: 12px;">pretreatment procedures providing results for accuracy (R, 73.1–118.3%), repeatability (RSD, 3.28–</span><span style="font-size: 12px;">10.40%) and within-laboratory reproducibility (RSD, 6.45–17.70%), limits of detection (LOD, 1.5–2.5 </span><span style="font-size: 12px;">gµ kg</span><sup><span style="font-size: 12px;">-1</span></sup><span style="font-size: 12px;">) and quantification (LOQ, 5.0–10.0 µg kg</span><sup><span style="font-size: 12px;">-1</span></sup><span style="font-size: 12px;">). For the first time, more than 100 honey samples </span><span style="font-size: 12px;">collected from all 7 counties of Autonomous Province of Vojvodina were analyzed. The presence of </span><span style="font-size: 12px;">thiacloprid, imidacloprid and thiametoxam was discovered in a small number of samples. The objective </span><span style="font-size: 12px;">of next study was to develop an optimized LC-MS/MS analytical method with DLLME and QuEChERS </span><span style="font-size: 12px;">procedures for analysis of 7 neonicotinoids in honey liqueur. The method was validated to fulfill the </span><span style="font-size: 12px;">requirements of SANCO/12495/2011 for both sample pretreatment procedures providing results for </span><span style="font-size: 12px;">accuracy (R, 69.2–113.4% for DLLME; 71.8–94.9% for QuEChERS), precision (RSD expressed in </span><span style="font-size: 12px;">terms of repeatability (3.21–10.20% for DLLME; 4.19–12.81% for QuEChERS) and within-laboratory </span><span style="font-size: 12px;">reproducibility (9.11–16.63% for DLLME; 11.32–16.40% for QuEChERS)), limits of detection (LOD, </span><span style="font-size: 12px;">0.5–1.5 gµ L</span><sup><span style="font-size: 12px;">-1 </span></sup><span style="font-size: 12px;">for DLLME; 1.0–2.5 gµ L</span><sup><span style="font-size: 12px;">-1 </span></sup><span style="font-size: 12px;">for QuEChERS) and quantification (LOQ, 1.0–5.0 gµ L</span><sup><span style="font-size: 12px;">-1 </span></sup><span style="font-size: 12px;">for </span><span style="font-size: 12px;">DLLME; 2.5–10.0 µg L</span><sup><span style="font-size: 12px;">-1 </span></sup><span style="font-size: 12px;">for QuEChERS). Analysis of real honey liqueur samples obtained from local </span><span style="font-size: 12px;">markets showed the presence of clothianidin or thiacloprid in four of the analyzed samples, therefore </span><span style="font-size: 12px;">implicating the necessity of ongoing control of this type of traditional product.  Removal of selected </span><span style="font-size: 12px;">neonicitinoid insecticides - dinotefuran, clothianidin and thiacloprid using MWCNT and H</span><span style="font-size: 12px;"><sub>2</sub>O<sub>2 </sub></span><span style="font-size: 12px;">from </span><span style="font-size: 12px;">Danube water matrix was investigated.  Efficiency of different systems for neonicotinoids removal </span><span style="font-size: 12px;">(under natural insolation in laboratory, with H</span><span style="font-size: 12px;"><sub>2</sub>O<sub>2</sub>, with MWCNT, with MWCNT+ H</span><span style="font-size: 12px;"><sub>2</sub>O<sub>2</sub>, with Fe-MWCNT, with Fe-MWCNT+H<sub>2</sub>O<sub>2</sub>) was evaluated with developed LC-MS/MS method. Analysis of </span><span style="font-size: 12px;">degradation rates revealed loss of 25% of the initial neonicotinoid concentration under natural insolation in </span><span style="font-size: 12px;">the laboratory conditions during 60 min. Addition of chemical agent H<sub>2</sub>O<sub>2 </sub>promoted loss of 40% of the </span><span style="font-size: 12px;">initial dinotefuran, 70% of thiacloprid concentration and total removal of clothianidin under same </span><span style="font-size: 12px;">conditions. With the addition  of MWCNT concentration of dinotefuran, clothianidin and thiacloprid </span><span style="font-size: 12px;">decayed for 30, 50 and 60%, respectively. Iron modification of MWCNT in combination with H</span><span style="font-size: 12px;"><sub>2</sub>O<sub>2 </sub></span><span style="font-size: 12px;">increased the removal rate of selected neonicotinoid for 15–50%. Presence of intermediates was </span><span style="font-size: 12px;">discovered in systems of dinotefuran with H<sub>2</sub>O<sub>2</sub>, MWCNT+H</span><span style="font-size: 12px;"><sub>2</sub>O<sub>2</sub>, e-MWCNT+H<sub>2</sub>O<sub>2 </sub></span><span style="font-size: 12px;">and of </span><span style="font-size: 12px;">clothianidin in systems with Fe-MWCNT+H<sub>2</sub>O<sub>2 </sub></span><span style="font-size: 12px;">with m/z of 117,5 and 140,6. </span></p>
34	Direkter Drucksensor unter Verwendung von Kohlenstoffnanoröhren-Nanokompositen Dinh, Nghia Trong 28 April 2016 (has links) Im Gegensatz zu herkömmlichen Dehnungsmessstreifen können Carbon nanotube (CNT)-basierte Komposite zusätzlich eine ausgeprägte Druck-abhängigkeit des Widerstandes aufweisen. Deshalb können Drucksensoren aus CNT-Nanokomposite ohne den Einsatz von Verformungskörpern wie z. B. Biegebalken aufgebaut werden. Die möglichen Anwendungsgebiete für diese direkt messenden Sensoren wurden in der vorliegenden Arbeit bei drei industriellen Anwendungen wie z. B. bei Robotergreifarmen gezeigt. Die Zielstellung dieser Arbeit ist die Entwicklung und Charakterisierung eines neuartigen Sensors aus CNT-Nanokomposite. Unter Verwendung von Multi-walled carbon nanotube (MWCNT)-Epoxidharz und interdigitalen Elektroden soll der Sensor auf wenigen Quadratzentimetern Drücke im Megapascal-Bereich und somit Kräfte im Kilonewton-Bereich messen können. Durch die Auswahl geeigneter Werkstoffe und die Modellierung mit der Finite Element Methode wurde der Sensorentwurf durchgeführt sowie der Messbereich abgeschätzt. Die Herstellung der MWCNT-Epoxidharz-Dispersion erfolgte durch mechanische Mischverfahren. Anschließend wurden aus der Dispersion druckempfindliche Schichten mit der Schablonendrucktechnik hergestellt. Dabei wurden die Herstellungs-parameter und besonders der Füllstoffgehalt der MWCNTs variiert, um deren Einflüsse auf das mechanische, thermische und elektrische Verhalten zu untersuchen. Die Charakterisierung der mechanischen Kenngrößen erfolgte mit Zugversuchen und dynamisch-mechanischer Analyse. In den Untersuchungen zeigen die MWCNT-Komposite eine signifikante Steigerung der Zugfestigkeit und eine Erhöhung der Glasübergangstemperatur gegenüber reinem Epoxidharz. Die Abhängigkeiten der Druckempfindlichkeit und der Temperaturempfindlichkeit vom Füllstoffgehalt wurden untersucht. Eine besonders hohe Druckempfindlichkeit, aber auch Temperaturempfind-lichkeit wurde bei Proben mit geringem Füllstoffgehalt (1 wt% und 1,25 wt%) festgestellt. Es ist also wichtig, die richtige Materialkombination für diese Art Sensor zu finden. Die realisierten Sensoren liefern zuverlässige Antwortsignale bei wiederholten Belastungen bis zu einer Belastung von 20 MPa (entspricht 2 kN). Zusätzlich wurde der Temperatureinfluss in einem Bereich von −20 °C bis 50 °C durch eine Wheatstonesche Brückenschaltung kompensiert. Die vorliegende Arbeit zeigt, dass eine zuverlässige Druckmessung mit einer Temperaturmessabweichung von 0,214 MPa/10 K gewährleistet werden kann. / In contrast to conventional metallic strain gauges, carbon nanotube (CNT) composites have an additional pressure sensitivity. Therefore, deformation elements such as bending beam is not needed by using pressure sensors, which are based on CNT nanocomposite. The possible areas of application for these pressure direct measured sensors were showed in three industrial application such as robot gripper. The focus of this work is the development and characterization of a new sensor manufactured from CNT nanocomposite. By using multi-walled carbon nanotube (MWCNT) epoxy and interdigital electrodes the sensor, which has a dimension of few square centimetre, should measure a pressure in mega Pascal range and hence a force in kilo newton range. By the selection of suitable materials and the modelling using finite element method, the sensor design as well as the measurement range were carried out. The MWCNT epoxy dispersion is manufactured by using a mechanical mixing process. Subsequent, the dispersion is used to fabricate pressure sensitive layers by stencil printing methods. Thereby, the fabrication parameters and especially the filler content of the MWCNTs were varied for the mechanical, thermal and electrical investigation. The characterization of the mechanical characteristic values were carried out by using tensile test and dynamic mechanical analysis. The results show a significant increasing of the tensile strength and glass transition temperature in comparison to neat epoxy. Additionally, the influence of the filler content to the pressure and thermal sensitivity were investigated. A highly pressure sensitivity but also a highly thermal sensitivity are obtained for samples with lower filler contents (1 wt% and 1.25 wt%). Therefore, a suitable material combination has to be chosen. The fabricated sensors show reliable response signals by repeated excitations up to 20 MPa (meets to 2 KN). Moreover, the temperature influence ranged from -20 °C to 50 °C was compensated with a Wheatstone bridge. This work demonstrate a direct pressure sensitive sensor with reliable response signals by a thermal deviation of 0.214 MPa/10K. info:eu-repo/classification/ddc/600 ddc:600 info:eu-repo/classification/ddc/607 ddc:607 info:eu-repo/classification/ddc/500 ddc:500 info:eu-repo/classification/ddc/537 ddc:537 info:eu-repo/classification/ddc/542 ddc:542
35	Voltametrijske metode zasnovane na primeni jednostavnih i savremenih elektroda/senzora na bazi ugljeničnih materijala za određivanje vodonik-peroksida u odabranim uzorcima / Voltammetric methods based on the application of simple and contemporary carbonaceousmaterials-based electrodes/sensors for the determination of hydrogen-peroxide in the selected samples Anojčić Jasmina 22 November 2018 (has links) <p>Cilj  ove  doktorske  disertacije  je  bio  razvoj  brzih  i  pouzdanih  voltametrijskih  metoda zasnovanih na primeni jednostavnih i savremenih elektroda/senzora na bazi ugljeničnih materijala (ugljenične  paste  napravljene  od  grafitnog  praha  i  parafinskog  ulja  i  &scaron;tampanih  ugljeničnih elektroda)  za  određivanje  H <sub>2</sub>O<sub>2 </sub>u  odabranim  složenim  model  i  realnim  uzorcima.  U  tu  svrhu, ispitana je primenljivost različitih radnih elektroda. Amperometrijska  metoda  zasnovana  na  elektrodi  od  ugljenične  paste  (CPE)  zapreminski modifikovane  sa  5%  (m:m)  MnO2 je,  pri  optimizovanim  uslovima  i  pri  radnom  potencijalu  od 0,40 V  u  odnosu  na  zasićenu  kalomelovu  elektrodu  (ZKE)  u  fosfatnom  puferu  pH  7,50  kao pomoćnom elektrolitu, omogućila kvantifikaciju H <sub>2</sub>O<sub>2</sub> u opsegu koncentracija od 1,4 do 65 µg mL -1 sa  relativnom  standardnom  devijacijom  (RSD)  manjom  od  10%.  Ova  metoda  je  primenjena  za određivanje sadržaja H <sub>2</sub>O<sub>2 </sub>u uzorcima podzemne vode iz centralnog Banata (Pokrajina Vojvodina, Srbija)  tretirane  Fentonovim  (Fe<sup> 2+</sup> i  H <sub>2</sub>O<sub>2</sub> )  i  Fentonu-sličnim  (Fe <sup>3+</sup> i  H <sub>2</sub>O<sub>2</sub> )  reagensima  u  cilju uklanjanja  prirodnih  organskih  materija  (POM)  pri  čemu  su  kori&scaron;ćene  različite  početne koncentracije  gvožđa  i  različiti  odnosi  molarnih  koncentracija  gvožđa  i  H <sub>2</sub>O<sub>2</sub> .  Utvrđeno  je  da oksidaciono  stanje  gvožđe  (Fe<sup> 2+</sup> ili  Fe <sup>3+</sup>)  i  molarni  odnos  jona  Fe  i  H<sub> 2</sub>O<sub>2</sub> utiču  na  stepen potro&scaron;nje/razgradnje  H<sub> 2</sub>O<sub>2</sub><br />u  podzemnoj  vodi  sa  visokim  sadržajem  POM.  Takođe,  u  slučaju Fentonu-sličnog  procesa,  za  sve  početne  koncentracije  Fe <sup>3+</sup> i  H <sub>2</sub>O<sub>2 ,</sub>  signifikantna  količina  H <sub>2</sub>O<sub>2 </sub>ostaje  neiskori&scaron;ćena,  &scaron;to  ukazuje  na  nižu  efikasnost  ovakvog  sistema u  poređenju  sa  Fentonovim procesom.&Scaron;tampana  ugljenična  elektroda  (SPCE)  zapreminski  modifikovana  sa  MnO 2 kao medijatorom  je  primenjena  za  određivanje  sadržaja  H<sub> 2</sub>O<sub>2</sub> u  toku  Fentonovog  (Fe <sup>2+</sup> ,  H<sub>2</sub>O<sub>2</sub> )  i vidljivom  svetlo&scaron;ću  potpomognutog  foto-Fentonovog  (Fe<sup> 2+ </sup>,  H <sub>2</sub>O<sub>2 </sub>,  hν)  procesa  uklanjanja neonikotinoidnog  insekticida  acetamiprida  (ACT).  Pri  optimizovanim  uslovima  (radni  potencijal 0,40  V  u  odnosu  na  ZKE,  fosfatni  pufer  pH  7,50  kao  pomoćni  elektrolit)  amperometrijskog određivanja  H <sub>2</sub>O<sub>2</sub> ,  postignuta  je  linearnost  u  opsegu  koncentracija  0,01–1,24  mmol  L-1(0,34– 42,2 µg 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  uzorkovanja radi stopiranja ili maksimalnog usporavanja  procesa  oksidacije,  filtriranja,  zamrzavanja  i  odmrzavanja  neposredno  pre  merenja) sadržaj  H <sub>2</sub>O<sub>2</sub> je  određen  metodom  standardnog  dodatka  analiziranjem  odgovarajućih amperometrijskih  krivi.  Paralelna  HPLC-DAD  merenja  su  vr&scaron;ena  u  cilju  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 µg mL -1 ) za ACT, Fe<br /><sup>2+</sup> i H <sub>2</sub>O<sub>2</sub>, redom) nakon 10 min H <sub>2</sub>O<sub>2 </sub>je izreagovao, a može se smatrati da je ACT uklonjen nakon 5 min. U toku Fentonovog procesa ACT je  uklonjen  nakon  20  min  tretmana  i  oko  10%  početne  koncentracije  H <sub>2</sub>O<sub>2</sub> je  ostalo  u  sistemu<br />neiskori&scaron;ćeno.CPE  je  povr&scaron;inski  modifikovane  kompozitom  na  bazi  nanočestica  Pt  (<  5  nm)  i grafitizovanog  ugljenika  (Pt-C,  10%  Pt  na  Vulkanu  XC72)   etodom  nano&scaron;enja  kapi. Nemodifikovana  CPE  i  modifikovana  (Pt-C/CPE)  su   okarakterisane  primenom  SEM/EDS  i  CV merenja.  Pt-C/CPE  je  pokazala  izuzetne  elektrokatalitičke  osobine  u  pogledu  elektrohemijskeredoks  reakcije  H<br /><sub>2</sub>O<sub>2</sub> u  poređenju  sa  nemodifikovanom  CPE  u  fosfatnom  puferu  (0,1 mol  L -1 ;<br />pH 7,50),  a  takođe  i  u  acetatnom  puferu  (0,1  mol  L -1 ;  pH  4,50)  kao   pomoćnim  elektrolitima. Prilikom  amperometrijskog  određivanja  H <sub>2</sub>O<sub>2</sub> primenom  Pt-C/CPE  u  model  sistemima, zadovoljavajuća linearnost je postignuta u koncentracionom opseguH<sub>2</sub>O<sub>2</sub>od 0,15 do 1,45 µg mL -1 ,dok su vrednosti GO iznosile 0,06 µg mL -1 (pH 7,50, radni potencijal 0,20 V) i 0,10 µg mL -1 (pH<br />4,50,  radni  potencijal  0,50  V).  Optimizovane  analitičke  metode  su  primenjene  za  određivanje sadržaja H <sub>2</sub>O<sub>2</sub> u komercijalno dostupnim proizvodima za ličnu negu: rastvoru za dezinfekciju (pH 7,50)  i  rastvoru  za  či&scaron;ćenje  kontaktnih  sočiva  (pH  4,50).  Amperometrijski  dobijeni  rezultati  su  u dobrom  slaganju  sa  rezultatima  dobijenim  primenom  tradicionalne  spektrofotometrijske  metode bazirane  na  titanijum-sulfatu  kao  reagensu  sa  određenim  koncentracijama  2,91%  i  2,94%  za<br />dezinfekcioni rastvor i 3,04% i 3,17% za rastvor zakontaktna sočiva, redom. RSD je bila manja od 2%.  Postignuti  rezultati  su  u  dobrom  slaganju  sa  sadržajem  H<br /><sub>2</sub>O<sub>2 </sub>deklarisanim  od  strane proizvođača (3%) u oba ispitivana uzorka. Pt-C/CPE je takođe testirana za praćenje koncentracije H<sub>2</sub>O<sub>2</sub> u rastvoru za kontaktna sočiva u toku procesa njegove neutralizacije/razgradnje. Nakon 6 h procesa neutralizacije, 24,68  µg mL -1 je bila određena koncentracija H <sub>2</sub>O<sub>2 ,</sub> &scaron;to je ispod dozvoljene<br />H<sub>2</sub>O<sub>2 </sub>koncentracije u rastvoru za kontaktna sočiva imajući u vidu granicu koja izaziva iritaciju oka. CPE  je  povr&scaron;inski  modifikovana  vi&scaron;ezidnim  ugljeničnim  nanocevima  (MWCNT)  i kompozitima MnO 2 -MWCNT ili Pt-MWCNT metodom nano&scaron;enja kapi radi pripreme jednostavnih, osetljivih i pouzdanih voltametrijskih senzora za  određivanje H <sub>2</sub>O<sub>2 </sub>u odabranom uzorku. Rezultati SEM/EDS  analize  kompozitnih  materijala  su  potvrdili da  su  medijatori,  čestice  MnO 2 i  Pt, nasumično  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  (pH  7,50)  i  boratnom  (pH  9,18)  puferu  kako  bi  se  okarakterisalo  osnovno elektrohemijsko  pona&scaron;anje  H <sub>2</sub>O<sub>2 </sub>i  odabrali  pogodni  radni  potencijali  za  amperometrijsko određivanje ovog ciljnog analita. Pt- WCNT/CPE je primenljiva za rad kako u fosfatnom puferu pH  7,50  tako  i  u  acetatnom  puferu  pH  4,50  V  kako  pri  negativnim  tako  i  pri  pozitivnim  radnim<br />potencijalima, pri  čemu su vrednosti RSD uglavnom ispod 2,5%. U slučaju MnO 2<br />-MWCNT/CPE, na  potencijalu  0,30  V  i  vi&scaron;im  vrednostima,  oksidacioni  signali  H<br /><sub>2</sub>O<sub>2</sub> su  signifikantni  u  blago alkalnoj sredini (pH 7,50), pri pH 4,50 ova elektroda pokazuje nezadovoljavajuće pona&scaron;anje, dok  pri pH 9,18 ima prihvatljive performanse. Granice određivanja (GO) su bile u oblasti µg mL -1 . H <sub>2</sub>O<sub>2</sub> je  određen  u  spajkovanom  uzorku  mleka  metodom  standardnog  dodatka  nakon  odgovarajuće pripreme  uzorka  (pH  pode&scaron;avanje  i  centrifugiranje)  i  primenom  optimizovane  amperometrijske procedure (acetatni pufer pH 4,50, radni  potencijal-0,75 V) koristeći Pt-MWCNT/CPE kao radnu elektrodu. RSD za tri  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  čestica na bazi Pd (Pd-MWCNT) ili Pt (Pt-MWCNT) su primenjeni za pripremu zapreminski modifikovanih SPCE (Pd-MWCNT-SPCE i Pt-MWCNT-SPCE)  i  povr&scaron;inski  modifikovane  SPCE  (Pd-MWCNT/SPCE).  Ove  elektrode,  kao  i nemodifikovana  SPCE  i  MWCNT-SPCE,  su  okarakterisane primenom  CV  i  amperometrije  u fosfatnom puferu pH 7,50 radi određivanja H <sub>2</sub>O<sub>2</sub> . Pd-MWCNT-SPCE i Pd-MWCNT/SPCE su se pokazale  pogodnim  za  određivanje  H <sub>2</sub>O<sub>2</sub> na  radnim  potencijalima  između  -0,50  i  0,50  V,  a  PtMWCNT-SPCE na ispitivanim radnim potencijalima od -0,80 do 0,70 V. Ove  elektrode su zatim modifikovane  enzimom  glukoza  oksidazom  (GOx)  metodom  nano&scaron;enja  kapi  rastvora  GOx  i Nafion ® -a  na  njihovu  povr&scaron;inu,  pri  čemu  je  optimizovana  količina  nanetog  biofilma.  GOx/PdMWCNT-SPCE  je  pokazala  bolje  analitičke  performanse  za  određivanje  glukoze  u  poređenju  sa GOx/Pd- WCNT/SPCE.  Kao  optimalan  radni  potencijal  GOx/Pd-MWCNT-SPCE  je  odabrana<br />vrednost  potencijala  -0,40  V  u  odnosu  na  ZKE,  sa  zadovoljavajućom  linearno&scaron;ću  u  ispitivanom opsegu  koncentracija  glukoze  od  0,16  do  0,97  mmol  L -1 (od  29,1  do  174  µg  mL -1),  dok  je  GO iznosila 0,14 mmol L -1 (25 µg mL<br />-1 ). Optimizovana metoda zasnovana na GOx/Pd-MWCNT-SPCE je  uspe&scaron;no  primenjena  za  određivanje  glukoze  u  uzorku  livadskog  meda.  Dobijeni  rezultati  su  u dobroj  saglasnosti  sa  onima  dobijenim  primenom  komercijalno  dostupnog  aparata  za  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 µg mL -1 , sa GO 35 µg mL -1 . Optimizovana metoda zasnovana na GOx/Pt-MWCNT-SPCE je  uspe&scaron;no  primenjena  za  određivanje  glukoze  u  u  uzorku  belog  grožđa  i  uzorku  tableta (Traubenzucker-bonbons),  pri  čemu  su  dobijeni  rezultati  u  dobroj  saglasnosti  sa  rezultatima dobijenim primenom Accu-Chek aparata.<br />Na  osnovu  dobijenih  rezultata  može  se  zaključiti  da  su  razvijene  analitičke  metode  pre svega jednostavne, pouzdane i pogodne za dobijanje brzih informacija o sadržaju H <sub>2</sub>O<sub>2</sub> u različitim tipovima  uzoraka.  Svakako  odabir  pogodne  radne  elektrode,  kao  i  optimizacija  eksperimentalnih uslova su ključni faktori za uspe&scaron;no određivanje H <sub>2</sub>O<sub>2</sub></p> / null / <p>The aim of this doctoral dissertation was the development of fast and reliable voltammetric methods  based  on  the  application  of  simple  and  contemporary  electrodes/sensors  based  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;"> </span><sub>2</sub><span id="cke_bm_571E" style="display: none;"> </span>O<sub>2</sub> in the selected complex model and real samples.For this purpose, applicability of different working electrodes was investigated.The  amperometric  method  based  on  carbon  paste  electrode  (CPE)  bulk- modified     with 5% (m:m) MnO 2 , under optimized conditions, with a working potential of 0.40 V vs. the saturated calomel  elect<span id="cke_bm_572E" style="display: none;"> </span>rode  (SCE)  and  a  phosphate  buffer  solution  (pH  7.50)  as  supporting  electrolyte, enabled the quantitation of H <span id="cke_bm_577S" style="display: none;"> </span><sub>2</sub><span id="cke_bm_577E" style="display: none;"> </span>O<sub>2</sub>in the concentration interval from 1.4 to 65 µg mL −1 with a relative standard deviation (RSD) of less than 10%. This meth<span id="cke_bm_578E" style="display: none;"> </span>od was applied for the determination of the H<span id="cke_bm_583S" style="display: none;"> </span><sub>2</sub><span id="cke_bm_583E" style="display: none;"> </span>O<sub>2 </sub>consumption  in  samples  of  groundwater  fro<span id="cke_bm_584E" style="display: none;"> </span>m  the  Central  Banat  region  (Province  of Vojvodina, Serbia) treated by the Fenton (Fe <sup>2+ </sup>and H <sub>2</sub>O<sub>2</sub> ) and Fenton-  like (Fe <sup>3+</sup>and H <sub>2</sub>O<sub>2</sub> ) reagents to remove natural organic matter (NOM) at  differentinitial concentrations of iron species, and of their molar ratios to the initial concentration of H<sub>2</sub>O<sub>2</sub> . It was found that the form of Fe (Fe <sup>2+</sup> or Fe <sup>3+</sup> )and the molar  ratio to H <sub>2</sub>O<sub>2</sub>influenced the degree of the H<sub> 2</sub>O<sub>2</sub> decomposition in the groundwater with high NOM content. Besides, in the case of the Fenton-like process, for all initial doses of Fe <sup>3+</sup> and H<span id="cke_bm_604S" style="display: none;"> </span><sub> 2</sub><span id="cke_bm_604E" style="display: none;"> </span>O<sub>2</sub>, a sign<span id="cke_bm_605E" style="display: none;"> </span>ificant amount of H<span id="cke_bm_610S" style="display: none;"> </span><sub> 2</sub><span id="cke_bm_610E" style="display: none;"> </span>O<sub>2</sub> remained unused, whi<span id="cke_bm_611E" style="display: none;"> </span>ch also indicates a lower efficiency of such system compared to the Fenton process. Screen  printed  carbon  electrode  (SPCE)  bulk-modified  with  MnO <sub> 2</sub> as  a  mediator  was applied  for  amperometric  determination  of  the  H <span id="cke_bm_617S" style="display: none;"> </span><sub>2</sub><span id="cke_bm_617E" style="display: none;"> </span>O<sub>2</sub> content  during  the  Fenton  (Fe <sup>2+</sup> ,  H <span id="cke_bm_624S" style="display: none;"> </span><sub>2</sub><span id="cke_bm_624E" style="display: none;"> </span>O<sub>2 </sub>)  and <span id="cke_bm_625E" style="display: none;"> </span>visible  light-assisted<span id="cke_bm_618E" style="display: none;"> </span>,  photo-Fenton  (Fe <sup>2+ </sup> ,  H <span id="cke_bm_631S" style="display: none;"> </span><sub>2</sub><span id="cke_bm_631E" style="display: none;"> </span>O<sub>2</sub> ,  hν)<span id="cke_bm_632E" style="display: none;"> </span>  based  removal  of  neonicotinoid  insecticide acetamiprid (ACT). Under  optimized conditions (working potential of 0.40 V vs. SCE, phosphate buffer  pH  7.50  as  supporting  electrolyte)  amperometric  determination  of  H <span id="cke_bm_637S" style="display: none;"> </span><sub>2</sub><span id="cke_bm_637E" style="display: none;"> </span>O<sub>2 </sub>showed  a  linear dynamic range from 0.01 to 1.24 mmol L -1 (from 0.34 to 42.2 µg 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;"> </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;"> </span><sub>2</sub><span id="cke_bm_643E" style="display: none;"> </span>O<sub>2</sub>  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;"> </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 µg mL -1 ) of ACT, Fe<sup> 2+</sup> and H <span id="cke_bm_650S" style="display: none;"> </span><sub>2</sub><span id="cke_bm_650E" style="display: none;"> </span>O<sub>2</sub>, respec<span id="cke_bm_651E" style="display: none;"> </span>tively) after 10 min of irradiation H <span id="cke_bm_656S" style="display: none;"> </span><sub>2</sub><span id="cke_bm_656E" style="display: none;"> </span>O<sub>2</sub> was  consumed  and  it  can  be  consi<span id="cke_bm_657E" style="display: none;"> </span>dered  that  ACT  was  removed  after  5  min.  During  the  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  was  surface  modified  with  a  composite  of  Pt  nanoparticles  (<  5  nm)  on  graphitized carbon (Pt-C, 10% Pt on Vulcan XC72) by simply dropcoating method. The unmodified CPE and the  modified  one  (Pt-C/CPE)  were  characterized  by   EM/EDS  and  CV  measurements.  The  PtC/CPE showed remarkable electrocatalytic propertiestoward the electrochemical redox reaction of H<span id="cke_bm_662S" style="display: none;"> </span><sub>2</sub><span id="cke_bm_662E" style="display: none;"> </span>O<sub>2</sub> compared to  modified CPE in phosphate buffer (0.1 mol L -1 ; pH 7.50), as well in acetatebuffer  (0.1 mol  L -1 ; pH .50) supporting  electrolytes. Amperometry of  H2O2 in the concentration range from 0.15 to 1.45 µg mL -1 with the Pt-C/CPE showed acceptable linearity, while the obtained values of LOQs were 0.06 µg mL -1  (pH 7.50, working potential 0.20 V) and 0.10 µg mL -1 (pH 4<span id="cke_bm_663E" style="display: none;"> </span>.50, working potential 0.50 V). The proposed analytical  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%  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;"> </span><sub> 2</sub><span id="cke_bm_668E" style="display: none;"> </span>O<sub>2 </sub>declared 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;"> </span><sub> 2</sub><span id="cke_bm_674E" style="display: none;"> </span>O<sub>2</sub> residual concentration in contact lens  solution  during  its  neutralization/decomposition  rocess.  At  6  h  of<span id="cke_bm_675E" style="display: none;"> </span>  neutralization  treatment 24.68 µg mL -1 of the H <span id="cke_bm_680S" style="display: none;"> </span><sub>2</sub><span id="cke_bm_680E" style="display: none;"> </span>O<sub>2 </sub>was  determined which is almost half of the allowedH2<span id="cke_bm_681E" style="display: none;"> </span>O2 concentration in the case of the contact lens solution concerningthe limit of eye irritation. CPE  was  surface   modified  with  multiwalled  carbon  nanotubes  (MWCNT)  and  with composites of MnO<sub> 2 </sub>-MWCNT or Pt-MWCNT by drop coating method to prepare simply, sensitive and reliable volta<span id="cke_bm_669E" style="display: none;"> </span>mmetric sensors for the determination of H <span id="cke_bm_687S" style="display: none;"> </span><sub>2</sub><span id="cke_bm_687E" style="display: none;"> </span>O<sub>2 </sub>in selected sample. The results of the  SEM/<span id="cke_bm_688E" style="display: none;"> </span>EDS  analysis  of  composite  materials  have  confirmed  that  the  mediators,  MnO <sub>2</sub> and  Pt  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  with prepared electrodes in acetate  (pH  4.50),  phosphate  (pH  7.50)  and  borate  (pH  9.18)  buffers  to  characterize  the  basic electrochemical  behavior  of  H <span id="cke_bm_694S" style="display: none;"> </span><sub>2</sub><span id="cke_bm_694E" style="display: none;"> </span>O<sub>2</sub> and  to  select  the  working  potentials  suitable  for  amperometric determination  of  this  target  analyte.  The  Pt-MWCNT/CPE  performs  well  in  phosphate  buffer pH .50 and acetate buffer solution pH 4.50 in the  negative as well as in the positive polarization range with RSD mainly lower than 2.5%. In case of MnO<sub> 2 </sub>-MWCNT/CPE at <span id="cke_bm_695E" style="display: none;"> </span>0.30 V and above the H<span id="cke_bm_701S" style="display: none;"> </span><sub>2</sub><span id="cke_bm_701E" style="display: none;"> </span>O<sub>2 </sub>oxidation signal is rem<span id="cke_bm_702E" style="display: none;"> </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 µg mL -1 concentration  range.  H<span id="cke_bm_707S" style="display: none;"> </span><sub>2</sub><span id="cke_bm_707E" style="display: none;"> </span>O<sub>2 </sub>was  determined  in  a  spiked  milk  sample  by  standard addition  method after  appropriate  sample  preparation  (pH  adjustment and  centrifugation)  and  using  optimized amperometric p<span id="cke_bm_708E" style="display: none;"> </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  composite  materials  consisting  of  MWCNT  and  Pd  (Pd-MWCNT)  or  Pt  containing particles  (Pt-WCNT)  were  applied  to  the  preparation  of  bulk- modified  SPCEs  (Pd-MWCNTSPCE and Pt-MWCNT-SPCE) and surface modifiedSPCE (Pd- MWCNT/SPCE). These electrodes, as well as unmodified SPCE and MWCNT-SPCE,  were characterized by CV and  amperometry  in phosphate  buffer  solution  of  pH  7.50  for  the  H<span id="cke_bm_713S" style="display: none;"> </span><sub> 2</sub><span id="cke_bm_713E" style="display: none;"> </span>O<sub>2 </sub>determination.  Pd-MWCNT-SPCE  and  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  oxidase (GOx) by drop coating a solution of GOxand Nafion ® on their surface, whereby the applied amount of biococktail was optimized. GOx/PdMWCNT-SPCE  showed  better  analytical  performance  for  glucose  determination  in  comparison with  GOx/Pd-MWCNT/SPCE.  The  optimal  working  potential  for  GOx/Pd-MWCNT- SPCE  was -0.40 V vs. SCE and <span id="cke_bm_714E" style="display: none;"> </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  µg mL -1 ), hile the LOQ was 0.14 mmol L -1 (25 µg mL -1 ). The optimized method based on GOx/Pd-MWCNT-SPCE was successfully applied to the determination of glucose in multifloral honey sample.  The results are in a good agreement with those  obtained by commercially available equipment for determination of glucose. Optimal working potential  for  GOx/Pt-MWCNT-SPCE  was  -0.50  V  vs.  SCE,  and  the   satisfactory  linearity  was obtained in the investigated concentration range ofglucose from 65.8 to 260.6  µg mL -1 , with LOQ of 35  µg 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  the  obtained  results  were  in  a  good  agreement  with  the  results  obtained  by  Accu-Chek device. Based on the results, the developed analytical methods are first of all simple, reliable and suitable  for  obtaining  fast  information  about  the  content  of  H <sub>2</sub>O<sub>2</sub> in  different  types  of  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 H<sub>2</sub>O<sub>2 </sub>.</p>

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