Biocatalytical synthesis of nanoparticles

Biokatalitička sinteza nanočestica je proces nastanka čestica reda veličine 100nm ili manje, u reakcijama u kojima kao katalizator služi enzim (biokatalizator). U ovome radu sintetizirane su nanočestice kalcijevog karbonata (CaCO3) pomoću produkta biokatalitičke hidrolize uree uz enzim ureazu. Sinteza nanočestica provedena je u redestiliranoj vodi pri temperaturi od T = 30 °C i T = 40 °C dodavanjem soli kalcijevog klorida u otopinu u kojoj se provodi reakcija hidrolize uree uz enzim ureazu. Ispitana je kinetika hidrolize uree uz ureazu pri temperaturi od T = 30 °C i T = 40 °C u redestiliranoj vodi te je opisana Michealis-Menteničinim kinetičkim modelom s uključenom nekompetitivnom inhibicijom kalcijevim ionima. Postavljen je matematički model sinteze nanočestica, te je validiran u kotlastom reaktoru. Sintetizirane nanočestice karakterizirane su pomoću pretražnog elektronskog mikroskopa. Na temelju snimljenih prikaza određene su njihove prosječne veličine.Biocatalytic synthesis of nanoparticles is the formation of particles having one or more dimensions of the order of 100nm or less, in the reaction in which an enzyme is used as catalyst (biocatalyst). In this work the synthesis of nanoparticles of calcium carbonate (CaCO3) was carried out using the products of biocatalytic hydrolysis of urea in the presence of an enzyme urease. Synthesis of nanoparticles was carried out in redistilled water at a temperature of T = 30 °C and T = 40 °C by adding calcium chloride salt in a solution in which hydrolysis reaction of urea with a urease enzyme was conducted. The kinetics of the hydrolysis of urea with urease at a temperature of T = 30 °C and T = 40 °C in redistilled water is described by one-substrate Michaelis-Menten kinetic model with non-competitive inhibition of calcium ions. Mathematical model of the process was proposed and it was validated by the experimental results gathered in the batch reactor. The synthesized nanoparticles were characterized by SEM (scanning electron microscope). Based on the pictures taken by the SEM the average size of particles was determined

Biocatalytical synthesis of nanoparticles

Biokatalitička sinteza nanočestica je proces nastanka čestica reda veličine 100nm ili manje, u reakcijama u kojima kao katalizator služi enzim (biokatalizator). U ovome radu sintetizirane su nanočestice kalcijevog karbonata (CaCO3) pomoću produkta biokatalitičke hidrolize uree uz enzim ureazu. Sinteza nanočestica provedena je u redestiliranoj vodi pri temperaturi od T = 30 °C i T = 40 °C dodavanjem soli kalcijevog klorida u otopinu u kojoj se provodi reakcija hidrolize uree uz enzim ureazu. Ispitana je kinetika hidrolize uree uz ureazu pri temperaturi od T = 30 °C i T = 40 °C u redestiliranoj vodi te je opisana Michealis-Menteničinim kinetičkim modelom s uključenom nekompetitivnom inhibicijom kalcijevim ionima. Postavljen je matematički model sinteze nanočestica, te je validiran u kotlastom reaktoru. Sintetizirane nanočestice karakterizirane su pomoću pretražnog elektronskog mikroskopa. Na temelju snimljenih prikaza određene su njihove prosječne veličine.Biocatalytic synthesis of nanoparticles is the formation of particles having one or more dimensions of the order of 100nm or less, in the reaction in which an enzyme is used as catalyst (biocatalyst). In this work the synthesis of nanoparticles of calcium carbonate (CaCO3) was carried out using the products of biocatalytic hydrolysis of urea in the presence of an enzyme urease. Synthesis of nanoparticles was carried out in redistilled water at a temperature of T = 30 °C and T = 40 °C by adding calcium chloride salt in a solution in which hydrolysis reaction of urea with a urease enzyme was conducted. The kinetics of the hydrolysis of urea with urease at a temperature of T = 30 °C and T = 40 °C in redistilled water is described by one-substrate Michaelis-Menten kinetic model with non-competitive inhibition of calcium ions. Mathematical model of the process was proposed and it was validated by the experimental results gathered in the batch reactor. The synthesized nanoparticles were characterized by SEM (scanning electron microscope). Based on the pictures taken by the SEM the average size of particles was determined

Porosity of acoustic wood-wool cement board

Wood-wool cement board (WWCB) is a porous composite material consisting of Portland cement inorganic binder mixed with wood-wool as reinforcement. It is widely used as thermal and acoustic insulator in buildings because of low density, high porosity, good fire resistance and compatibility with other binders and building materials. The maority of composite characteristics, including as density, strength, oung modulus, gas permeability, thermal conductivity, and thermal diffusivity, are dependent on porosity. Aside from density, the other ualities stated, including sound absorption coefficient, are affected by pore sie distribution. The acoustic properties of airWWCB interaction are described through air complex modulus and air complex effective density used in many acoustic models for porous materials. Two techniues for determining porosity are used and compared on samples of wood-wool cement board from normal manufacturing received from FAMAT H d.o.o. Sv. ri arete, Croatia. The Archimedes techniue is utilied to determine the real and apparent density of the bulk WWCB, while image analysis of the surface layer and deeper layers reached by grinding and polishing is used to analye layer by layer porosity and pore sie distribution. The approaches are compared based on their complexity, length of analysis, and the type and uality of information obtained

Sol-gel Synthesis and Characterization of Lithium and Cerium Codoped Perovskite

Perovskites are an important group of ceramic materials with a structural formula ABO3 and wide array of potential applications in electronics, superconductors, catalysis, etc. CaTiO3, by which the whole group was named for, is particularly significant due to its use in catalysis, but its photocatalytic activity is limited by a large band gap value (~3.5 eV). A possible solution is the substitution of A and B cations with foreign cations which causes the alteration of properties, including photocatalytic efficiency. The aim of this work was the sol-gel synthesis of lithium and cerium codoped CaTiO3, characterization of the prepared gel and ceramics obtained by its thermal treatment. Samples of codoped perovskite, Ca1-xLixCexTiO3, where x = 0, 0.01, 0.02, 0.03 and 0.04, were prepared and characterized using powder X–ray diffraction (XRD), Fourier transformed infrared spectroscopy (FTIR), differential thermal and thermo- gravimetric analysis (DTA-TGA), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). Photocatalytic activity was evaluated through the study of methylene blue photocatalytic degradation. XRD analysis showed that the prepared samples consisted of calcium nitrate and titanium chelate. In accordance with the established thermal evolution path, all samples were thermally treated at 500 °C for 2 hours. Beside perovskite, Ca2Ti2O6 appeared as a secondary phase in all thermally treated samples. SEM analysis of thermally treated samples showed the presence of agglomerates of irregular morphology and the decrease of primary particles size with the increase of dopants concentration. The sample with x=0.04 showed an increased photocatalytic activity

Biocatalytical synthesis of nanoparticles

Biokatalitička sinteza nanočestica je proces nastanka čestica reda veličine 100nm ili manje, u reakcijama u kojima kao katalizator služi enzim (biokatalizator). U ovome radu sintetizirane su nanočestice kalcijevog karbonata (CaCO3) pomoću produkta biokatalitičke hidrolize uree uz enzim ureazu. Sinteza nanočestica provedena je u redestiliranoj vodi pri temperaturi od T = 30 °C i T = 40 °C dodavanjem soli kalcijevog klorida u otopinu u kojoj se provodi reakcija hidrolize uree uz enzim ureazu. Ispitana je kinetika hidrolize uree uz ureazu pri temperaturi od T = 30 °C i T = 40 °C u redestiliranoj vodi te je opisana Michealis-Menteničinim kinetičkim modelom s uključenom nekompetitivnom inhibicijom kalcijevim ionima. Postavljen je matematički model sinteze nanočestica, te je validiran u kotlastom reaktoru. Sintetizirane nanočestice karakterizirane su pomoću pretražnog elektronskog mikroskopa. Na temelju snimljenih prikaza određene su njihove prosječne veličine.Biocatalytic synthesis of nanoparticles is the formation of particles having one or more dimensions of the order of 100nm or less, in the reaction in which an enzyme is used as catalyst (biocatalyst). In this work the synthesis of nanoparticles of calcium carbonate (CaCO3) was carried out using the products of biocatalytic hydrolysis of urea in the presence of an enzyme urease. Synthesis of nanoparticles was carried out in redistilled water at a temperature of T = 30 °C and T = 40 °C by adding calcium chloride salt in a solution in which hydrolysis reaction of urea with a urease enzyme was conducted. The kinetics of the hydrolysis of urea with urease at a temperature of T = 30 °C and T = 40 °C in redistilled water is described by one-substrate Michaelis-Menten kinetic model with non-competitive inhibition of calcium ions. Mathematical model of the process was proposed and it was validated by the experimental results gathered in the batch reactor. The synthesized nanoparticles were characterized by SEM (scanning electron microscope). Based on the pictures taken by the SEM the average size of particles was determined

Optimization of calcium manganite synthesis

U ovome radu optimirana je priprava kalcijevog manganita, pri čemu je ispitano nekoliko metoda sinteze: mehanokemijska, Pechinijeva, modificirana Pechinijeva te ručna homogenizacija. Dobiveni uzorci su kalcinirani na temperaturama 400 – 1200 °C radi dobivanja kristalnog kalcijevog manganita. Sastav prašaka sintetiziranih navedenim metodama ispitan je rendgenskom difrakcijskom analizom, infracrvenom spektroskopijskom analizom, te kombiniranom diferencijalnom pretražnom kalorimetrijom i termogravimetrijskom analizom. Morfologija prašaka dobivenih Pechinijevom i metodom homogenizacije, kao najefikasnijim metodama sinteze, promatrana je pretražnom elektronskom mikroskopijom (SEM), a također je određena raspodjela veličina čestica i njihova specifična površina. Kao najefikasnija metoda odabrana je ručna homogenizacija koja daje relativno brzo, jednostavno i lagano kalcijev manganit. Stoga su iz tog praška pripravljeni uzorci za ispitivanje nanošenja tankih filmova iz suspenzija i metodom laserske ablacije (PLD). Suspenzije su pripravljene iz praška kalciniranog na 900 °C. Najpostojanije su se pokazale suspenzije u etanolu, no zbog velikih čestica nije bilo moguće dobiti homogenu prevlaku. Mete za metodu PLD dobivene su tabletiranjem iz praška kalciniranog na 900 °C te nekalciniranog prašaka. Tablete su žarene na 900 i 1200 °C te je morfologija vanjske i lomne površine ispitivana SEM-om. Tablete žarene na 900 °C nisu dovoljno sinterirane i previše su krhke, dok su one žarene na 1200 °C u potpunosti sinterirane i dovoljno kvalitetne za primjenu kao mete. Tablete dobivene iz nekalciniranih prašaka imaju krupnije kristale, ali su isto tako i poroznije zbog oslobađanja CO2 i vlage iz sirovog praška prilikom sinteriranja.In this work the synthesis of calcium manganite was optimised through a number of different methods of synthesis: mechanochemical, manual homogenisation, Pechini and modified Pechini method. To achieve crystalline calcium manganite synthesised samples were annealed on temperatures from 400 °C to 1200 °C. Synthesised powder samples were characterised with X-ray diffraction analysis, infrared spectroscopy, differential scanning calorimetry and thermogravimteric analysis. Morphology of the powders synthesized by Pechini methods and manual homogenisation was observed by scanning electron microscope (SEM), and the particle distribution and specific surface area were determined. The manual homogenisation method was proven as the most efficient for fast, easy and simple synthesis of calcium manganite. Powder synthesised by this method was further used for drop-castings from suspensions and pulsed laser deposition (PLD) for creating thin films. Suspensions were made with powders annealed at 900 °C, ethanol suspensions were the most stable for the longest time. Particle size of powders was too great to produce fine homogeneous films. Targets for laser ablation were obtained by compaction of powders annealed at 900 °C into tablets. Tablets were annealed at 900 and 1200 °C and their surface and fracture morphology was characterized with SEM. Tablets annealed at 900 °C showed low state of sintering and high brittleness, while tablets annealed at 1200 °C had high state of sintering and were strong enough to be used as targets for PLD. Higher state of porosity was represented in tablets made from non-calcined powders due to release of CO2 and moisture during the process of sintering. These tablets also had larger crystal grains

Optimization of calcium manganite synthesis

U ovome radu optimirana je priprava kalcijevog manganita, pri čemu je ispitano nekoliko metoda sinteze: mehanokemijska, Pechinijeva, modificirana Pechinijeva te ručna homogenizacija. Dobiveni uzorci su kalcinirani na temperaturama 400 – 1200 °C radi dobivanja kristalnog kalcijevog manganita. Sastav prašaka sintetiziranih navedenim metodama ispitan je rendgenskom difrakcijskom analizom, infracrvenom spektroskopijskom analizom, te kombiniranom diferencijalnom pretražnom kalorimetrijom i termogravimetrijskom analizom. Morfologija prašaka dobivenih Pechinijevom i metodom homogenizacije, kao najefikasnijim metodama sinteze, promatrana je pretražnom elektronskom mikroskopijom (SEM), a također je određena raspodjela veličina čestica i njihova specifična površina. Kao najefikasnija metoda odabrana je ručna homogenizacija koja daje relativno brzo, jednostavno i lagano kalcijev manganit. Stoga su iz tog praška pripravljeni uzorci za ispitivanje nanošenja tankih filmova iz suspenzija i metodom laserske ablacije (PLD). Suspenzije su pripravljene iz praška kalciniranog na 900 °C. Najpostojanije su se pokazale suspenzije u etanolu, no zbog velikih čestica nije bilo moguće dobiti homogenu prevlaku. Mete za metodu PLD dobivene su tabletiranjem iz praška kalciniranog na 900 °C te nekalciniranog prašaka. Tablete su žarene na 900 i 1200 °C te je morfologija vanjske i lomne površine ispitivana SEM-om. Tablete žarene na 900 °C nisu dovoljno sinterirane i previše su krhke, dok su one žarene na 1200 °C u potpunosti sinterirane i dovoljno kvalitetne za primjenu kao mete. Tablete dobivene iz nekalciniranih prašaka imaju krupnije kristale, ali su isto tako i poroznije zbog oslobađanja CO2 i vlage iz sirovog praška prilikom sinteriranja.In this work the synthesis of calcium manganite was optimised through a number of different methods of synthesis: mechanochemical, manual homogenisation, Pechini and modified Pechini method. To achieve crystalline calcium manganite synthesised samples were annealed on temperatures from 400 °C to 1200 °C. Synthesised powder samples were characterised with X-ray diffraction analysis, infrared spectroscopy, differential scanning calorimetry and thermogravimteric analysis. Morphology of the powders synthesized by Pechini methods and manual homogenisation was observed by scanning electron microscope (SEM), and the particle distribution and specific surface area were determined. The manual homogenisation method was proven as the most efficient for fast, easy and simple synthesis of calcium manganite. Powder synthesised by this method was further used for drop-castings from suspensions and pulsed laser deposition (PLD) for creating thin films. Suspensions were made with powders annealed at 900 °C, ethanol suspensions were the most stable for the longest time. Particle size of powders was too great to produce fine homogeneous films. Targets for laser ablation were obtained by compaction of powders annealed at 900 °C into tablets. Tablets were annealed at 900 and 1200 °C and their surface and fracture morphology was characterized with SEM. Tablets annealed at 900 °C showed low state of sintering and high brittleness, while tablets annealed at 1200 °C had high state of sintering and were strong enough to be used as targets for PLD. Higher state of porosity was represented in tablets made from non-calcined powders due to release of CO2 and moisture during the process of sintering. These tablets also had larger crystal grains

Optimization of calcium manganite synthesis

U ovome radu optimirana je priprava kalcijevog manganita, pri čemu je ispitano nekoliko metoda sinteze: mehanokemijska, Pechinijeva, modificirana Pechinijeva te ručna homogenizacija. Dobiveni uzorci su kalcinirani na temperaturama 400 – 1200 °C radi dobivanja kristalnog kalcijevog manganita. Sastav prašaka sintetiziranih navedenim metodama ispitan je rendgenskom difrakcijskom analizom, infracrvenom spektroskopijskom analizom, te kombiniranom diferencijalnom pretražnom kalorimetrijom i termogravimetrijskom analizom. Morfologija prašaka dobivenih Pechinijevom i metodom homogenizacije, kao najefikasnijim metodama sinteze, promatrana je pretražnom elektronskom mikroskopijom (SEM), a također je određena raspodjela veličina čestica i njihova specifična površina. Kao najefikasnija metoda odabrana je ručna homogenizacija koja daje relativno brzo, jednostavno i lagano kalcijev manganit. Stoga su iz tog praška pripravljeni uzorci za ispitivanje nanošenja tankih filmova iz suspenzija i metodom laserske ablacije (PLD). Suspenzije su pripravljene iz praška kalciniranog na 900 °C. Najpostojanije su se pokazale suspenzije u etanolu, no zbog velikih čestica nije bilo moguće dobiti homogenu prevlaku. Mete za metodu PLD dobivene su tabletiranjem iz praška kalciniranog na 900 °C te nekalciniranog prašaka. Tablete su žarene na 900 i 1200 °C te je morfologija vanjske i lomne površine ispitivana SEM-om. Tablete žarene na 900 °C nisu dovoljno sinterirane i previše su krhke, dok su one žarene na 1200 °C u potpunosti sinterirane i dovoljno kvalitetne za primjenu kao mete. Tablete dobivene iz nekalciniranih prašaka imaju krupnije kristale, ali su isto tako i poroznije zbog oslobađanja CO2 i vlage iz sirovog praška prilikom sinteriranja.In this work the synthesis of calcium manganite was optimised through a number of different methods of synthesis: mechanochemical, manual homogenisation, Pechini and modified Pechini method. To achieve crystalline calcium manganite synthesised samples were annealed on temperatures from 400 °C to 1200 °C. Synthesised powder samples were characterised with X-ray diffraction analysis, infrared spectroscopy, differential scanning calorimetry and thermogravimteric analysis. Morphology of the powders synthesized by Pechini methods and manual homogenisation was observed by scanning electron microscope (SEM), and the particle distribution and specific surface area were determined. The manual homogenisation method was proven as the most efficient for fast, easy and simple synthesis of calcium manganite. Powder synthesised by this method was further used for drop-castings from suspensions and pulsed laser deposition (PLD) for creating thin films. Suspensions were made with powders annealed at 900 °C, ethanol suspensions were the most stable for the longest time. Particle size of powders was too great to produce fine homogeneous films. Targets for laser ablation were obtained by compaction of powders annealed at 900 °C into tablets. Tablets were annealed at 900 and 1200 °C and their surface and fracture morphology was characterized with SEM. Tablets annealed at 900 °C showed low state of sintering and high brittleness, while tablets annealed at 1200 °C had high state of sintering and were strong enough to be used as targets for PLD. Higher state of porosity was represented in tablets made from non-calcined powders due to release of CO2 and moisture during the process of sintering. These tablets also had larger crystal grains

Combustion Synthesis of Zirconium-Doped Ceria Nanocatalyst

Zirconium-doped ceria is a promising and extensively researched catalytic material with notable use in three-way catalytic converters, the oxidation of volatile organic compounds and solid oxide fuel cells. In this work, pure and zirconium-doped ceria nanoparticles (Ce1−xZrxO2, where x = 0, 0.1, 0.2, and 0.3) were prepared by combustion synthesis using glycine as the fuel and cerium and zirconium nitrate as oxidants. The obtained powders were characterized using X-ray powder diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, differential thermal and thermogravimetric analysis, UV–Vis diffuse reflectance spectroscopy, and X-ray photoelectron spectroscopy. The combustion temperature increases with the increase in zirconium content in the samples, but the XRD patterns exclusively show ceria diffraction peaks. The crystallite sizes are in the range from 25.2 to 11.7 nm, and do not vary substantially after thermal treatment, indicating the good thermal stability of the prepared nanocatalysts. XPS analysis showed that the surface amount of zirconium is lower than the nominal and that the ceria sample with 10 mol. % of zirconium has a higher amount of oxygen vacancies than the 30 mol. % Zr-doped sample. The 10 mol. % Zr-doped sample displays the best catalytic activity in the BTEX (benzene, toluene, ethylbenzene, and o-xylene) oxidation process