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1.
Removal of neodymium ions from aqueous solution by magnetic nanoparticles
Ana Ambrož, 2021, magistrsko delo

Opis: This work is focused on the synthesis and characterization of surface-functionalized γ-Fe2O3-NH4OH@SiO2(APTMS) nanoparticles, their applications, and performance for Nd3+ removal from aqueous solutions, with an emphasis on the characterization of MNPs and Nd(NO3)3•6H2O. The γ-Fe2O3 nanoparticles were obtained by the co-precipitation method, stabilized with ammonia solution, and functionalized by SiO2 and APTMS. Neodymium nitrate hexahydrate (Nd(NO3)3•6H2O) used in aqueous solution was synthesised from neodymium oxide (Nd2O3) powder. The thermal behaviour and stability of the magnetic nanoparticles and Nd(NO3)3•6H2O was studied with thermogravimetric analysis (TGA) in O2, N2, and air atmosphere. Transmission electron microscopy (TEM) images were obtained in order to analyse the particle morphology and measure the size distribution of the nanoparticles. The hydrodynamic diameter of particles and the zeta potential were measured to determine the stability of particles in the solution. ATR-FTIR spectroscopy was used to confirm the functionalization of the magnetic nanoparticles and the adsorption of Nd3+ ions. The effect of the REE adsorption on the MNPs was studied by comparing the sample’s UV-Vis absorption spectra. The laboratory testing and analysis of the results indicate promising applications for the removal of the REE from aqueous solutions with magnetic nanoparticles. However, the coating of the MNP core by SiO2(APTMS) is inefficient for the removal of Nd3+ ions.
Ključne besede: Magnetic nanoparticles, Rare earth elements, Neodymium, Adsorption, Zeta potential, UV-Vis spectroscopy
Objavljeno: 03.05.2021; Ogledov: 95; Prenosov: 22
.pdf Celotno besedilo (2,51 MB)

2.
Modificiranje zeolitov za izboljšanje selektivnosti pri separaciji plinov
Mitja Čuš, 2019, diplomsko delo

Opis: Diplomsko delo je potekalo v sodelovanju s podjetjem Silkem d.o.o v njihovem raziskovalnem laboratoriju. Delo zajema modificiranje zeolitov z namenom, da izboljšamo separacijo plinov, natančneje kisika in dušika iz atmosferskega zraka. Namen diplomskega dela je ugotoviti in laboratorijsko preveriti kateri zeoliti so primerni za molekularna sita za namene adsorpcije pod povišanim tlakom in pod podtlakom. Zeolit Na13X smo modificirali z ionsko izmenjavo s CaCl2 in s tem dobili zeolit Ca13X. Molekularna sita so temeljnega pomena pri separaciji zraka s procesom adsorpcije pod povišanim tlakom (PSA-pressure swing adsorption) in adsropcije pod podtlakom (VPSA-vacuum pressure swing adsorption). PSA in VPSA sta procesa pridobivanja oziroma bogatenja kisika, ki sta energetsko manj potratna kot pridobivanje kisika z uveljavljenimi metodami kot je to utekočinjanje zraka (ohlajevanje zraka), med seboj pa se razlikujeta po obratovalnem tlaku. Zeolitna molekularna sita se uporabljajo za proizvodnjo medicinskega kisika v kisikovih generatorjih. Raziskovali smo kako vplivajo struktura zeolita, obratovalni tlak, višina kolone in zadrževalni čas na učinkovitost adsorpcije. Velja, da je separacija zraka učinkovitejša z večjo aktivno površino zeolita, separacijski učinek pa višji z višjim obratovalnim tlakom. Višja kot je kolona, daljši je zadrževalni čas, z večanje višine pa je tudi večja količina polnila, kar pomeni večjo aktivno površino in s tem boljšo adsorpcijo. Modifikacija zeolita Na13X je potekala tako, da smo omenjen zeolit dodali v raztopino CaCl2 in šaržo intenzivno mešali 48 ur. Šaržo smo nato prefiltrirali in posušili. Ca13X smo granulirali v laboratoriju z Eirichovim granulatorju. Zeolitu Ca13X smo dodali deionizirano vodo in vezivo atapulgit ter granulirali do velikosti, primerne za nasutje. Pred uporabo zeolita smo granule kalcinirali pri 500 °C, saj s kalcininacijo dosežemo aktivacijo zeolita in izparevanje vlage ter drugih adsorbiranih snovi. Z aktiviranimi zeoliti smo napolnili kolono in merili koncentracijo kisika na izhodu s kisikovim merilcem. Ugotovili smo, da je ionsko izmenjan kalcijev zeolit Ca13X bolj primeren za molekularno sito pri separaciji plinov iz zraka. Visoke koncentracije kisika doseže tudi zeolit 5A, vendar je za procesa PSA in VPSA bolj primeren kalcijev zeolit Ca13X.
Ključne besede: ionska izmenjava, zeolit 13X, kalcijev zeolit 13X, adsorpcija, Pressure swing adsorption, Vacuum pressure swing adsorption, separacija zraka.
Objavljeno: 10.10.2019; Ogledov: 429; Prenosov: 84
.pdf Celotno besedilo (1,24 MB)

3.
A laboratory characterization of soils and clay-bearing rocks using the Enslin-Neff water-adsorption test
Ana Petkovšek, Matej Maček, Bojan Majes, 2009, izvirni znanstveni članek

Opis: The application of the Enslin-Neff water-adsorption test for the determination of soil-index properties has been investigated on commercially available reference minerals and on real soils. The Enslin-Neff test is a simple and reliable laboratory method, which can provide important information about the behavior of soils, clay-bearing rocks and aggregate fines that are in contact with water. Although the test has been frequently used for bentonite testing, practically no results have been published about the physical meaning of the Enslin-Neff water-adsorption values for real soils. The results of this study indicate that the Enslin-Neff water-adsorption test can be used to obtain accurate values of some soil-index properties, such as the liquid limit, the plasticity index, the methylene-blue value, and the soil-water characteristic curve.
Ključne besede: water adsorption, soil water characteristic curve, methylene blue value, soil suction
Objavljeno: 06.06.2018; Ogledov: 674; Prenosov: 64
.pdf Celotno besedilo (380,52 KB)
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4.
Protein adsorption on various plasma-treated polyethylene-terephthalate substrates
Nina Recek, Morana Jaganjac, Metod Kolar, Lidija Milković, Miran Mozetič, Karin Stana-Kleinschek, Alenka Vesel, 2013, izvirni znanstveni članek

Opis: Protein adhesion and cell response to plasma-treated polymer surfaces were studied. The polymer polyethylene terephthalate (PET) was treated in either an oxygen plasma to make the surface hydrophilic, or a tetrafluoromethane CF4 plasma to make the surface hydrophobic. The plasma source was radiofrequency (RF) discharge. The adsorption of albumin and other proteins from a cell-culture medium onto these surfaces was studied using a quartz crystal microbalance (QCM), X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). The cellular response to plasma-treated surfaces was studied as well using an MTT assay and scanning electron microscopy (SEM). The fastest adsorption rate was found on the hydrophilic oxygen plasma-treated sample, and the lowest was found on the pristine untreated sample. Additionally, the amount of adsorbed proteins was higher for the oxygen-plasma-treated surface, and the adsorbed layer was more viscoelastic. In addition, cell adhesion studies support this finding because the best cell adhesion was observed on oxygen-plasma-treated substrates.
Ključne besede: oxygen and fluorine plasma treatment, polymer surface modification, protein adsorption, cell adhesion, quartz crystal microbalance, QCM
Objavljeno: 22.06.2017; Ogledov: 513; Prenosov: 285
.pdf Celotno besedilo (2,39 MB)
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5.
Polymer nanocomposite hydrogels for water purification
Manja Kurečič, Majda Sfiligoj-Smole, 2012, samostojni znanstveni sestavek ali poglavje v monografski publikaciji

Ključne besede: polymer nanocomposites, wastewaters, coloures wastewaters, clay minerals, dye adsorption, hydrogels
Objavljeno: 10.07.2015; Ogledov: 809; Prenosov: 67
URL Povezava na celotno besedilo

6.
PB(II) AND HG(II) IONS ADSORPTION USING SURFACE MODIFIED SUPERPARAMAGNETIC IRON OXIDE NANOPARTICLES
2014, doktorska disertacija

Opis: Cobalt ferrite (CoFe2O4) nanoparticles prepared via co-precipitation method were modified with tetraethoxysilane (TEOS) and additional funkcionalized with 3-mercaptopropyl trimethoxysilane (MPTMS) with purpose of cleaning waste water contaminated with heavy metal ions (Pb2+ and Hg2+). The influence of different experimental parameters (reaction time, reaction temperature and different TEOS:MPTMS ratios) on silica coating of CoFe2O4 nanoparticles and additional on thiol group was systematically studied. Silanes adsorb to the particle surface with alkoxy (Si(OR)4) groups at one end, while functional substituents (-SH) at the opposite end stay extended into surrounding aqueous medium and chemically interact with heavy metal contaminates. Thiol functionalized CoFe2O4 nanoparticles were characterized using IR spectroscopy, X-ray diffraction (XRD), transmission electron microscopy/high-resolution transmission electron microscopy (TEM/HRTEM), energy-dispersive X-ray spectroscopy (EDXS) and vibrating-sample magnetometer (VSM). The thiol functionalized CoFe2O4 nanoparticles were used for Pb2+ and Hg2+ions adsorption from aqueous media. Effect of treatment has been demonstrated using atomic absorption spectroscopy (AAS).
Ključne besede: cobalt ferrite, magnetic nanoparticles, tetraethoxysilane, 3-mercaptopropyl trimetoxysilane, thiol group, lead, mercury, adsorption
Objavljeno: 02.12.2014; Ogledov: 1869; Prenosov: 116
.pdf Celotno besedilo (5,22 MB)

7.
Manipulation of chitosan binding on the polyethylene terephthalate (PET) surface and study of coatings on poultry meat shelf life-time
Tina Tkavc, 2014, doktorska disertacija

Opis: The aim of this study was to activate inert PET surfaces in order to introduce the surfaces’ carboxyl groups and to obtain its hydrophilic character, which was important for the chitosan bonding to it. Films where chitosan was attached to the PET could be used as active packaging material for food like fresh poultry meat. For PET activation two advanced and environmentally friendly techniques were used: 1) O2 plasma activation; and 2) CO2 plasma activation. Differently treated PET foils deposited on Au quartz crystals (model studies - adsorption and desorption) and real films were characterized. Later on, real films were studied in the terms of carboxylic/amino group content, hydrophobic/hydrophilic character, surface composition and adsorption/desorption of chitosan onto/from the surface. Results clearly showed that the use of both surfaces’ activation processes increased the ability of PET foils to adsorb chitosan, but CO2 plasma gave a higher concentration of carboxyl groups on the PET surface and consequently, due to the chemical bonding the chitosan layers were more stable. Even though CO2 plasma pre-treated PET foils gave better results during the experimental work, we could not avoid layer by layer adhesion of chitosan which resulted in non-bound molecules. Pre-treated foils and with chitosan functionalized foils were tested preliminarily with ASTME E1 (2002) microbiological tests. Functionalized CO2 plasma pre-treated foils gave the broadest spectra of antimicrobial activity, and therefore they were chosen for further microbiological analyses, where chitosan`s influence on inoculated poultry models towards selected standard strains, typical for poultry meat, was being tested. By determining the MIC (minimal inhibitory concentration) for selected microorganisms we have proven, that chitosan possesses antimicrobial properties at low concentrations. During the transfer of the experiment to a larger scale (food models, which are a very complex environment), it has been shown that on PET bonded chitosan did not have the inhibitory effect to that extent, with the exception of Staphylococcus aureus, as was expected. Similar results were expressed using both these methods: Colony count technique and real-time PCR. In the end, the organoleptic properties of the chicken models exposed to foils have shown that chitosan changes the color and taste of meat immediately after exposure, but samples were staying edible longer. Therefore, functionalized PET, which has an inhibitory influence towards variety of microorganisms, may be applied as an active packaging system for poultry meat after some optimization of the coating procedure in binding chitosan onto the PET surfaces.
Ključne besede: PET/chitosan/antimicrobial packaging/adsorption-desorption kinetics/microbiological tests
Objavljeno: 22.10.2014; Ogledov: 1627; Prenosov: 153
.pdf Celotno besedilo (3,65 MB)

8.
Adsorption of fucoidan and chitosan sulfate on chitosan modified PET films monitored by QCM-D
Tea Indest, Janne Laine, Leena Sisko Johansson, Karin Stana-Kleinschek, Simona Strnad, Renate Dworczak, Volker Ribitsch, 2009, izvirni znanstveni članek

Opis: The adsorption behavior of fucoidan as well as chitosan derivatives (chitosan sulfate) on poly(ethylene terephthalate) (PET) model film surface was studied using the quartz crystal microbalance technique. These systems were chosen for this study due to their promising biocompatible properties. Moreover, fucoidan and chitosan sulfate have promising anticoagulant properties and represent an alternative to heparin treatment of vascular grafts. As a first step, PET foils were activated by alkaline hydrolysis to increase their hydrophilicity. From these foils, model PET films were prepared by the spin coating technique on a silica quartz crystal. The selected polysaccharides (chitosan, fucoidan, and chitosan sulfate) were adsorbed from aqueous solutions on the PET surfaces. The adsorption was monitored using a quartz crystal microbalance with a dissipation unit. The surface chemistry and morphology of the chitosan/fucoidan or chitosan/chitosan sulfate coated PET-H films was analyzed using XPS and AFM. It was found that chitosan/fucoidan films were thinner and more compressed, while in the case of chitosan/chitosansulfate, large amounts of chitosan sulfate were adsorbed, indicating a loose and thick adsorbed film.
Ključne besede: PET films, fucoidan, chitosan sulfate, adsorption, anticoagulant properties
Objavljeno: 01.06.2012; Ogledov: 1376; Prenosov: 82
URL Povezava na celotno besedilo

9.
Removal of inorganic As [sup] 5+ from a small drinking water system
Marjana Simonič, 2009, izvirni znanstveni članek

Opis: The drinking water from a small drinking water system contained arsenic in a concentration of about 50 ▫$mu$▫g/L. Chemical analyses showed that the pentavalent form of arsenic was present. Since the MCL value is 10 ▫$mu$▫g/L, it was necessary to implement a technological treatment to make the water suitable for drinking. In order to do so, two technologies were suggested: activated alumina and ▫$alpha$▫-FeOOH (TehnoArz, TA) adsorption media. Experiments using both adsorption media were performed on a laboratory scale. It was possible to remove arsenic to below 1 ▫$mu$▫g/L. The maximal adsorption capacity was found to be 12.7 mg of As5+ per gram of ▫$alpha$▫-FeOOH. Moreover, all the important physico- chemical parameters of the water remained practically unchanged after the treatment. Only a slight release of iron from the media was observed. The Fe-As bond was studied by means of chemical analysis and X-ray powder diffraction. Finally, in addition to showing the capability of arsenic removalby ▫$alpha$▫-FeOOH, a comprehensive optimization of the technological parameters of the selected technology is provided.
Ključne besede: drinking water, arsenic, activated alumina, goethite, adsorption
Objavljeno: 01.06.2012; Ogledov: 1310; Prenosov: 31
URL Povezava na celotno besedilo

10.
Removal of vat and disperse dyes from residual pad liquors
Vera Golob, Alenka Ojstršek, 2005, izvirni znanstveni članek

Opis: The efficiency of three wastewater treatment techniques, coagulation/flocculation, adsorption and ultrafiltration, has been studied for the removal of vat and disperse dyes from residual pad liquors. Three inorganic coagulants Al2(SO4)3 18H2O, FeSO4 7H2O, FeCl3 6H2O and commercial cationic flocculant, as individuals and in combination, were tested for the coagulation/flocculation methods. Granular activated carbon was used as an adsorbent in the adsorption technique. Ultrafiltration was performed using a polyethersulfone membrane with a molecular weight cut-off of 10 kDa. Dye removal was evaluated as the difference between concentrations of dyes in pad liquors before and after a particular treatment using absorbance measurements.The obtained results indicated over 90% of dye removal using appropriate coagulants and only 40% using activated carbon. The best results, dye removal over 98%, were achieved using the ultrafiltration technique.
Ključne besede: textile dyeing, disperse dyes, wastewater, decoloration, wastewater treatment, coagulation, flocculation, adsorption, ultrafiltration, vat dyes
Objavljeno: 01.06.2012; Ogledov: 1608; Prenosov: 90
URL Povezava na celotno besedilo

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