Polypyrrole-based Enzyme Electrode with Immobilized Glucose Oxidase for Electrochemical Determination of Glucose

Polypyrrole enzyme electrode was formed by immobilization of glucose oxidase via glutaraldehyde into electrochemically synthesized polypyrrole on glassy carbon electrode. Electrochemical synthesis was performed in 0.5 mol dm(-3) HCl and 0.2 mol dm(-3) pyrrole at constant current density of 2 mA cm(-2). Chronopotentiometric curves of polypyrrole enzyme electrode were recorded at current density of 42 nA cm(-2) for different glucose concentrations. The determined value of the apparent Michaelis-Menten constant was 0.045 mmol dm(-3) which is significantly lower than that of free enzyme indicating enhanced enzyme efficiency when it is immobilized into electroconducting polymer matrix

Uniaxial tension of drying sieves

Although the literature contains numerous studies that have been developed to describe the nonlinear behavior of drying sieves' operation, there are no papers in this which report deeper investigation of the drying sieve behavior when exposed to tension and thermo stabilization. The aim of this paper is to provide insight into the elastoplastic behavior of the thermo stabilized and not stabilized sieves subjected to the tensile force. Within this work both theoretical and experimental investigations were performed. The sieves were joined by using a spiral. In separate experiments tests of wire base and weft of the weave mesh were performed, both for thermo stabilized and not thermo stabilized sieves, sieves joining and the sieve thermo stabilization itself. It was established that the thermo stabilization of sieves provides for stability of sieves' dimensions and that open thermo stabilized drying sieve exhibits better mechanical properties and exploitation characteristics then the sieves joining. [Projekat Ministarstva nauke Republike Srbije, br. ON174004: Micromechanics criteria of damage and fracture and br. TR 32036: Development of software for solving the coupled multi-physical problems

Characteristics of the citrate-based zinc-polyaniline secondary cell with supercapattery behavior

The electrochemical characteristics of zinc–polyaniline (PANI) secondary cell in the electrolyte containing 0.8 M Na citrate, 0.3 M NH4Cl and 0.3 M ZnCl2 is investigated. Based on the measurements of potentials and voltage of the cell during charge/discharge for the currents in the range of 18 to 45 mA, the specific electrode capacity of 85 to 55 mA h g-1, the specific energy of 60–40 mW h g-1 and the specific power of 150–350 mW g-1, is determined. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. ON172046: Electrochemical synthesis and characterization of nanostructured functional materials for applications in new technologies

Electrochemical energy sources based on a metal | electroconducting polymers system from water solutions

U оvоm rаdu su ispitаnе mоgućnоsti primеnе pоlimеrа pоliаnilinа (PАNI) i pоlipirоlа (pPu) kао kаtоdnih mаtеriјаlа u kоmbinаciјi sа аnоdаmа оd Zn, Mg i Аl zа pоtеnciјаlnu primеnu u еlеktrоhеmiјskim izvоrimа struје (ЕIЕ). PАNI i PPu su pоlimеrizаоvаni еlеktrоhеmiјskim pоstulkоm u rаstvоru оdgоvаrајučćеg mоnоmеrа i HC1 i оkаrаktеrisаn tеhnikоm cikličnе vоltаmеtriје. Pоkаzаnо је dа еlеktrоdа nа bаzi pPu, i аkо pоsеduје dоbrе еlеktrоhеmiјskе kаrаktеristikе, niје pоgоdnа zа upоtrеbu u ЕIЕ uslеd intеnzivnе dеgrаdаciје pоlimеrа. Rеzultаti ipitivаnjа еlеktrоdе nа bаzi PАNI ukаzаli su nа pоstојаnjе dvе fоrmе PАNI (еmеrаldin i pеrningrаnilin), kао i nа dеgrаdаciјu PАNI. Ispitаn је uticаја rN vrеdnоsti i rаzličitih аnјоnа nа dеgrаdаciјu PАNI sа cilјеm izbоrа pоgоdnоg еlеktrоlitа zа ЕIЕ i njеgоvе dаlје оptimizаciје. Izаbrаn је еlеktrоlit hlоrid/citrаt pri rN - 5 јеr је u оvоm rаstvоru utvrđеnа smаnjеnа kоrоziја ispitivаnih mеtаlа. Dаlјim ispitivаnjimа, pоkаzаnо је dа је јеdinо Zn mоgućе kоristiti u ЕIЕ. Ispitаnо је i оptimizоvаnо u rеаlnim uslоvimа pоnаšаnjе еlеktrоdа оd PАNI i Zn u rаstvоru hlоrid/citrаt. Utvrđеnо је dа је iskоrišćеnjе struје no Zn оkо 95% zа struје vеćе оd 5 mA cm-2, pа је u rеаlnоm sistеmu, rаdnа pоvršinа PАNI еlеktrоdе bilа pеt putа vеćа. Dоbiјеnе su dоbrе nаpоnskе kаrаktеristikе tоkоm 20 ciklusа rаdа, а nаpоn оtvоrеnоg kоlа је biо stаbilin u tоku dеsеt dаnа i iznоsiо је оkо 1.4 V. Utvrđеnо је dа је sаmоprаžnjеnjе оvоg sistеmа оkо 1.5 % dnеvnо, štо је u sklаdu sа sаmоprаžnjеnjеm sistеmа sа pоliаnilinskim еlеktrоdаmа.The possible application of polyaniline (PANI) and polypyrrole (pPy) as cathodic materials combined to Zn, Mg and Al as anodic materials in electrochemical power sources were investigated. Electrochemical polymerization of PANI and pPy was performed from HC1 solution containing suitable monomer while cyclic voltammetry technique was used for characterization. It was shown that, apart from its good electrochemical characteristics, pPy electrode was not suitable for use in electrochemical power sources, due to intensive degradation. It was observed that PANI excised in two different forms emeraldine and perningraniline salt and that degradation of PANI occurred as well. Influence of pH and various anions on degradation of PANI was investigated in order to choose electrolyte for electrochemical power sources and its optimization. It was shown that in chloride/citrate electrolyte at pH~5, because on this pH values is reduced corrosion of investigated metals. Further investigation was shown that only Zn can be used in electrochemical power sources. Behavior of the real system PANI and Zn electrode was investigated and optimized in chloride/citrate electrolyte. It was observed that current efficiency for Zn was about 95% for current grater than 5 mA cm-2, and because of that, in the real system working area of the PANI electrode was five times greater than Zn electrode. For such system, good voltage characteristics during working 20 cycles were obtained. The open circuit voltage of 1.4 V was stable during 10 days. It was observed that the self discharge of the system was about 1.5% per day, which is in accordance to the self discharge of systems with PANI electrode

Elektrohemijska sinteza elektroprovodnih polimera

Electroconducting polymers from the group of synthetic metals are extensively investigated due to numerous properties perspective in practical application. These materials may be synthesized by both chemical and electrochemical procedures. Chemical synthesis is suitable when bulk quantities of the polymer are necessary and up to date it presents dominant commercial method of producing electroconducting polymers. Nevertheless, the electrochemical synthesis has its advantages; it avoids usage of oxidants since conducting polymeric material is obtained at anode upon application of positive potential, leading to increased purity. On the other hand, since the polymer is deposited onto electrode, further electrochemical characterization is facilitated. Owing to actuality of the research in the field, this text aims to describe important aspects of electrochemical synthesis of electroconducting polymers, with special emphasis to polyaniline and polypyrrole.Tradicionalno shvatanje o polimerima kao odličnim izolatorima izmenjeno je sedamdesetih godina prošlog veka kada su naučnici uspeli da sintetizuju poiliacetilen čija je provodljivost bila bliska metalnoj. Ova činjenica ukazala je na novo svojstvo polimernih materijala i lansirala potpuno novo multidisciplinarno naučno polje, popularno nazvano, sintetički metali. Iako je danas pojmom elektroprovodnih polimera obuhvaćena velika grupa jedinjenja koja su klasifikovana prema prirodi prenosioca naelektrisanja, naziv elektroprovodni polimeri se najčešće koristi u literaturi upravo za polimerne materijala iz grupe sintetičkih metala koji poseduju elektronsku provodljivost kao posledicu specifičnosti molekulske strukture. Pored zahteva molekulske structure, koja podrazumeva konjugovani sistem dvostrukih veza, za provodljivost elektroprovodnih polimera neophodno je dopovanje. Termin dopovanje, iako preuzet iz terminologije klasičnih neorganskih poluprovodnika, podrazumeva u mnogome drugačiji proces. Dopovanje elektroprovodnih polimera podrazumeva oksidaciju tokom koje se, u cilju održavanja elektroneutralnosti polimernog lanca, uvodi stehiometrijska količina jona (anjona). Terminom dopovanje obuhvaćena je i protonacija polimernog lanca kiselinom, u slučaju polianilina, a nedavno je potvrđena i u slučaju polipirola. Kako je, na ovaj način, uvedena velika količina jona izmenjenja je polazna struktura elektroprovodnog polimera, tako da svojstva nastalog materijala zavise u velikoj meri od svojstava dopanta. Iako su na početku razvoja ove oblasti, elektroprovodni polimeri bili sintetizovani hemijskim postupcima, sticanjem uvida u mehanizam hemijske sinteze koja podrazumeva oksidativnu radikalnu polimerizaciju, postalo je jasno da se ovi materijali mogu dobiti i elektrohemijskim postupcima. Elektrohemijska sinteza ima prednosti, pošto se polimer dobija oksidacijom na elektrodama (anodama), čime je izbegnuta upotreba oksidacinog sredstva i omogućena veća čistoća proizvoda. Sa druge strane, elektroprovodni polimer je u većini slučajeva dobijen u obliku prevlake na elektrodi, pa je njegova dalja karakterizacija elektrohemijskim tenikama olakšana. Interesovanje za oblst sinteze elektroprovodnih polimera ne jenjava, pa je ovaj tekst posvećen osnovnim principima elektrohemijskih postupaka sinteze sa posebnim osvrtom na najpopularnije elektroprovodne polimere, polianilin i polipirol

Electrochemical Water Treatment Devices

Paper published in 43rd International October Conference on Mining and Metallurgy - IOC 2011, October 12-15, 2011, Kladovo, Serbia: Proceedings, Bor : Technical Faculty, 2011

Characteristics of polyaniline lead - dioxide power sources

Polyaniline (PANI) anode, electrochemically synthesized on graphite electrode from sulfuric acid solution, and electrochemically formed thin film lead dioxide cathode, were investigated for possible applications as electrode materials in PANI | H2SO4 | PbO2 aqueous based rechargeable power sources. The stimulation of charge/discharge characteristics of the cell, based on half cell reactions investigations, was evaluated. Charging of the cell would occur in the voltage range of 1.2 and 1.7 V, while discharge would occur in the range of 1.3 and 1 V

Universal modular device for electrochemical syntesis of the disinficant

For the water disinfections practically four different technologies (chlorine, ozone, hypochlorite, chlorine dioxide) are used nowadays in the world. The oldest and the most exploited one, so called conventional, is the disinfections with gaseous or liquid chlorine. The biggest producers of the equipment for the water treatment in the world mainly possess all mentioned technologies for water disinfections. It is easy to concluded that the technology of water disinfections with the hypochlorite solution produced by the electrolysis of 3% solution of sodium chloride on the site of water chlorination is not only the most convenient from the point of economical aspects, but also from the point of the ecological aspect

Electrochemical characterization of polyaniline electrode for use in electrochemical power sources

Polyaniline (PANI) electrode was formed by electrochemical synthesis on graphite under galvanostatic condition at current density of 2.0 mA cm-2 from aqueous solution of 1.0 mol dm-3 HCl and 0.25 mol dm-3 aniline. Electrochemical characterization of the PANI electrode was performed in 0.5 mol dm-3 HCl using cyclic voltammetry and galvanostatic measurements. The overall charge capacity of the PANI electrode was estimated to be 0.154 mA h cm-2, corresponding to 25 % of the theoretical mass of PANI available for the dopant exchange. It was observed that during initial cyclization at low pH, the extent of PANI degradation products was insignificant and practically had no influence on the charge/discharge characteristics of the PANI electrode

Sinteza i koroziono ponašanje polianilina na mekom čeliku, bakru i aluminijumu iz benzoatnih rastvora

The electrochemical synthesis of polyaniline (PANI) on mild steel, aluminum and copper from the sodium benzoate solutions has been investigated. It has been shown that thin, highly adherent, polyaniline films on the investigated metals could be obtained by anodic oxidation with current densities in the range of 0.5 and 1.5 mA cm-2. The corrosion behavior of mild steel, aluminum and copper with polyaniline coating in 0.5 mol dm3 NaCl (pH 3) solutions, has been investigated by polarization technique. The corrosion current densities, porosity and protection efficiency was determined. It has been shown that polyaniline coating provided corrosion protection of all mentioned metals.U radu je ispitivana elektrohemijska sinteza polianilina (PANI) na mekom čeliku, aluminijumu i bakru iz rastvora natrijum-benzoata i monomera anilina. Ustanovljeno je da se tanki, dobro adherentni, filmovi polianilina mogu formirati na svim ispitivanim metalima pri anodnim gustinama struja od 0,5-1,5 mA cm-2. Ispitivano je koroziono ponašanje metala sa prevlakom polianilina u rastvoru 0,5 mol dm-3 NaCl (3%). Ustanovljeno je da ove prevlake pružaju korozionu zaštitu svim ispitivanim metalima u datoj korozionoj sredini