Search

[EN] The present study describes the surface modification of iron oxide magnetic nanoparticles with a double-shell coating of silica to obtain mesoporous superparamagnetic nanocomposites with high surface area, identified as nanoreactors (NRs), capable of providing a confined space for organic and inorganic pollutants removal. Adsorption tests were carried out for Lead (Pb2+) and methyl orange (MO) and the effects of different parameters such as pH, pollutant initial concentration, and contact time were analysed. The pseudo second-order model best described the adsorption kinetics for all NRs in the adsorption process of both, organic and inorganic pollutants. Intraparticle diffusion was also found to be involved in the MO adsorption, but is not the limiting stage. The adsorption isotherms were best described by the Langmuir model, suggesting that the adsorption takes place in monolayer. The maximum adsorption capacity value increases from 35 up to 50 mg/gNR with the increasing surface area for Pb2+ removal, while for MO it goes up to 240 mg/gNR. The NRs have excellent cyclability for MO sorption/desorption by simple acid treatment, recovering 100%during the first 4 cycles.

Fe(acac)3/silica/PVA hybrid xerogel nanocomposite was obtained by one pot acid catalysed sol-gel synthesis using the homogeneous mixture of iron(III) acetylacetonate (Fe(acac)3), tetraethylorthosilicate (TEOS), and polyvinyl alcohol (PVA). Nominal composition ratio of iron oxide/silica was 15/85 (weight percent). Nitric acid was used as catalyst. Another sample of Fe(acac)3/silica xerogel without PVA addition was prepared in the similar processing conditions. Based on thermal analysis studies, the thermal behaviour of both xerogel samples was unveiled and it allowed choosing the optimal calcination temperatures in order to obtain iron oxide silica magnetic nanocomposite samples. The two xerogel (with and without PVA) samples were thermally treated, in air, at 220, 260 and 300?C and characterized by different techniques. XRD investigations revealed phase composition evolution with calcination temperature, from cubic spinel phase (maghemite) to hexagonal stable hematite containing nanocomposite of 10-20 nm average crystallite size. These findings were confirmed by M?ssbauer spectroscopy. Up to 300?C, the surface area and total pores volume increased with temperature for all samples. By calcination at the same temperature, the hybrid xerogel containing PVA resulted in significantly higher magnetization and free volume values in comparison with the sample without PVA.

Bu yüksek lisans tez çalışmasında hidrotermal yöntemle katyonik yüzey aktif madde (CTAB) kullanılarak Fe3O4 ve NiFe2O4 nanopartikülleri hazırlanmıştır. Bununla birlikte poliol yöntemi ile iyonik likit (1-butil-3-metil-imidazolyum tetrafloroborat BMIMBF4) ortamında Mn3O4 elde edilmiştir. Bu nanopartiküllerin, yapısal, spektroskopik, morfolojik, manyetik ve elektriksel özellikleri detaylı olarak çalışılmıştır. Nanopartiküll/polibenzimidazol hibrit yapıları, kaplamanın homojen olması açısından iyonik likit (1-butil-3-metil-imidazolyum bromür [BMIM]Br) ortamında hazırlanmıştır. Elde edilen nanopartikül kompozitleri için SEM, TEM, XRD, FT-IR, VSM ve TGA analizleri yapılmış ve yapıları aydınlatılmıştır. Anahtar Kelimeler: polibenzimidazoller, iyonik likit, süperparamanyetik nanokompozitler, In this master thesis, NiFe2O4 using Fe3O4 nanoparticles were prepared with hydrothermal method by cationic surfactant (CTAB). However Mn3O4 were obtained in ionic liquid media (1-butyl-3-methyl-imidazolium tetraflouroborate BMIMBF4) with the polyol method. The spectroscopic, morphological, magnetic and electrical properties of this nanoparticles structural were studied in detail. For the homogeneous coating of nanoparticles/polybenzimidazoles hybrid structure was prepared the ionic liquid (1-butyl-3-methyl-imidazolium bromide [BMIM]Br) in medium. The resulting composite nanoparticles were performed SEM, TEM, XRD, FT-IR, VSM and TGA analyzes and nanocomposite structures were illuminated. Keywords: polybenzimidazoles, ionic liquids, superparamagnetic nanocomposites, Bu tez çalışması BAP tarafından 14201026 nolu proje ile desteklenmiştir.