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Removal of neodymium ions from aqueous solution by magnetic nanoparticles
Ana Ambrož, 2021, master's thesis

Abstract: 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.
Keywords: Magnetic nanoparticles, Rare earth elements, Neodymium, Adsorption, Zeta potential, UV-Vis spectroscopy
Published: 03.05.2021; Views: 94; Downloads: 22
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Compost leachate treatment using polyaluminium chloride and nanofiltration
Marjana Simonič, 2017, original scientific article

Abstract: Laboratory scale filtration tests utilizing leachate were conducted to investigate fouling and filtration performance of nanofiltration membranes. The work presented in this study is conducted on real samples rather than model water. Physico-chemical analyses showed that the leachate contained a lot of organic substances, exceeding 20000 mg/L O2 expressed as chemical oxygen demand. Proper pre-treatment method must be chosen in order to reduce fouling index. Coagulation pre-treatment using poly-aluminium chloride was chosen. Two thin film polysulfone membranes were used, purchased by Osmonic Desal. The focus of this research is to assess the influence of the particle size and zeta-potential of the colloidal fraction in leachate on nanofiltration performance. The isoelectric point of both membranes was 4.7 and 4.3, respectively. The fouled membranes were negatively charged over the pH range with isoelectric point shifting to the left (lower pH) indicating the foulant material mainly not charged. It was confirmed by its zeta-potential, measured at -2 mV.
Keywords: compost leachate, coagulation, nanofiltration, zeta potential
Published: 29.06.2017; Views: 919; Downloads: 266
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Substrate-induced coagulation (SIC) of nano-disperse titania in non-aqueous media : the dispersibility and stability of titania in N-methyl-2-pyrrolidinone
Angelika Basch, Simona Strnad, Volker Ribitsch, 2009, original scientific article

Abstract: Dispersions of 1 wt% titandioxide (titania or TiO2) were investigated with respect to their stability in non-aqueous media. The objective of this work was to find conditions for the substrate-induced coagulation (SIC) process in N-methyl-2-pyrrolidinone (NMP). The SIC process is a dip-coating process that enhances adsorption of fine dispersed particles on a pre-conditioned surface. The wetting behavior of titania and NMP was investigated by the powder contact angle method. The absorption process of the polar solvent NMP on the acid oxide TiO2and Aerosol OT (AOT) (bis-2-ethylhexyl sodium sulfosuccinate) was also investigated and a polar or hydrophilic interaction was found. The stability of titania in NMP dispersions and the influence of the solvent AOT and the electrolyte LiCl was investigated. By studying the electrophoretic mobilities of titania particles in NMP and the influence on solutes by the electrophoretic method phase analysis light scattering (PALS) and the electroacoustic method this paper explores suitable conditions for non-aqueous substrate-induced coagulation of titania.
Keywords: contact angle, non-aqueous dispersions, electrophoretic mobilities, substrate-induced coagulation, titandioxide, zeta potential
Published: 01.06.2012; Views: 1588; Downloads: 69
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Electrokinetic investigation of polyelectrolyte adsorption and multilayer formation on a polymer surface
Stefan Köstler, Volker Ribitsch, Karin Stana-Kleinschek, Georg Jakopic, Simona Strnad, 2005, original scientific article

Abstract: Self assembled polyelectrolyte layers of poly(sodium 4-styrenesulfonate) (PSS), and poly(diallyldimethylammonium chloride) (PDADMAC) were deposited on planar poly(ethylene terephthalate) (PET) substrates using the layer-by-layer technique. Charged functional groups were generated on the polymer substrates by means of a surface modification procedure prior to polyelectrolyte adsorption. The layers were characterised concerning their electrokinetic properties. The build-up of multilayer architectures could be followed by changes of the zeta-potential versus pH curves. An increase of coating density with increasing layer number was found. The electrokinetic properties of the PET substrates were not recognised anymore if more then four layers were applied. If PSS formed the outermost layer these assemblies were very stable against shear forces while if PDADMAC formed the outermost layer the films were partially destroyed by high shear forces.
Keywords: textile materials, polyelectrolyte multilayers, layer-by-layer assembly, zeta-potential, ellipsometry, polymer substrate, layer stability
Published: 01.06.2012; Views: 1633; Downloads: 64
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Zeta potential determination of polymeric materials using two differently designed measuring cells of an electrokinetic analyzer
Hermina Bukšek, Thomas Luxbacher, Irena Petrinić, 2010, original scientific article

Abstract: The so-called zeta potential can be determined through electrokinetic measurements and indicates the status regarding surface charges along the interface between solids and liquids. Surface charge gives us information about the condition, quality, and characteristics of a macroscopic surface in the polar medium. In our study the zeta potential was determined using a 'SurPASS' electrokinetic analyzer based on the streaming current and streaming potential measurements. The aim of the research was to compare the results of two differently designed measuring cells ('Adjustable Gap Cell' and 'Clamping Cell') but operating on the same principle. In order to investigate this problem, the zeta potential was determined for the three polymeric materials: poly(ethylene terephthalate) foil, thin-film polyamide composite membranes for nanofiltration and reverse osmosis. The results obtained with 'Clamping Cell' versus 'Adjustable Gap Cell' showed differences in zeta potential, where the 'Adjustable Gap Cell' gave more reproducible results. One reason for this behaviour could be the different geometries of the streaming channels. A more likely reason is the design of the 'Clamping Cell', that requires a sample size larger than necessary for zeta potential determination.
Keywords: electrical double layer, zeta potential, electrokinetic analyser, streaming current potential, polymeric materials
Published: 31.05.2012; Views: 1150; Downloads: 92
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