Synthesis of New Composites of Inorganic Polymers (Geopolymers) with Metal Oxide Nanoparticles and their Photodegradation of Organic Pollutants

<p>This thesis describes the development and performance of novel photocatalytic inorganic polymer (geopolymer) composites for photodegradation of environmentally harmful organic materials. Nanometer-sized cubic cuprous oxide nanoparticles and spherical Cu₂O/TiO₂ nano-heterostructures were synthesized via a precipitation method and then added to a metakaolinite-based geopolymer matrix prior to curing at ambient temperature. The morphology of the homogeneous oxide nanoparticle dispersion within the geopolymer matrix was demonstrated by SEM/EDS and HRTEM. FTIR spectroscopy confirmed the formation of a well-reacted geopolymer matrix that was unaffected by the insertion of the Cu₂O and Cu₂O/TiO₂ nanoparticles. The structures of these new composites were determined by ²⁷Al and ²⁹Si MAS NMR spectroscopy. ⁶³Cu NQR spectroscopy and XRD confirmed that the metal oxide nanoparticles are unchanged by their incorporation in the geopolymer composite and after the photodegradation reactions. The nitrogen adsorption-desorption isotherms were determined, providing information about the specific surface areas and total pore volumes of the composites. The action of the composites in the adsorption and photocatalytic destruction of the model organic compound MB was determined under dark and UV illumination conditions. Experiments in dark conditions and under UV irradiation showed that these materials efficiently remove a model organic pollutant (MB dye) from solution by a dual process of adsorption on the geopolymer matrix, and photodecomposition of the dye without destroying the geopolymer structure. The adsorption kinetics of the dye are best described by a pseudo first-order model and the adsorption process by Langmuir-Freundlich isotherms. In a novel extension of this research, the metakaolinite-based geopolymer matrix was modified with a surfactant (cetyltrimethylammonium bromide, CTAB), exploiting the cation exchange capacity of the geopolymers structure. The nano oxide composites were synthesised by adding different amounts of as-prepared metal oxide nanoparticles to the modified geoplymer to produce a hydrophobic photocatalyst composite with improved photocatalytic activity arising from the dispersion of the metal oxide nanoparticles in the external surfaces and interlayers of the geopolymer matrix. This method has the advantage of producing geopolymer composites with a stable pH which are more suitable for dye degradation studies. At concentrations >20 wt%, the photo-oxide component decreases the adsorption rate by blocking the active adsorption sites of the geopolymer. Under UV radiation, the composites remove the MB by a combination of adsorption and photodegradation, without deterioration of the geopolymer structure or the photoactive metal oxide component. In addition these studies show that the metal oxide-geopolymer nano composites have significantly improved photocatalytic activity compared with the oxide nanoparticles alone, because of the unique properties of these inorganic polymers. These results demonstrate that composites of nanosized Cu₂O particles and photoreactive TiO₂ in an aluminosilicate inorganic polymer matrix constitute new and novel materials with potential environmental protection applications to efficiently remove organic pollutants from water or the atmosphere.</p>

Synthesis of New Composites of Inorganic Polymers (Geopolymers) with Metal Oxide Nanoparticles and their Photodegradation of Organic Pollutants

<p>This thesis describes the development and performance of novel photocatalytic inorganic polymer (geopolymer) composites for photodegradation of environmentally harmful organic materials. Nanometer-sized cubic cuprous oxide nanoparticles and spherical Cu₂O/TiO₂ nano-heterostructures were synthesized via a precipitation method and then added to a metakaolinite-based geopolymer matrix prior to curing at ambient temperature. The morphology of the homogeneous oxide nanoparticle dispersion within the geopolymer matrix was demonstrated by SEM/EDS and HRTEM. FTIR spectroscopy confirmed the formation of a well-reacted geopolymer matrix that was unaffected by the insertion of the Cu₂O and Cu₂O/TiO₂ nanoparticles. The structures of these new composites were determined by ²⁷Al and ²⁹Si MAS NMR spectroscopy. ⁶³Cu NQR spectroscopy and XRD confirmed that the metal oxide nanoparticles are unchanged by their incorporation in the geopolymer composite and after the photodegradation reactions. The nitrogen adsorption-desorption isotherms were determined, providing information about the specific surface areas and total pore volumes of the composites. The action of the composites in the adsorption and photocatalytic destruction of the model organic compound MB was determined under dark and UV illumination conditions. Experiments in dark conditions and under UV irradiation showed that these materials efficiently remove a model organic pollutant (MB dye) from solution by a dual process of adsorption on the geopolymer matrix, and photodecomposition of the dye without destroying the geopolymer structure. The adsorption kinetics of the dye are best described by a pseudo first-order model and the adsorption process by Langmuir-Freundlich isotherms. In a novel extension of this research, the metakaolinite-based geopolymer matrix was modified with a surfactant (cetyltrimethylammonium bromide, CTAB), exploiting the cation exchange capacity of the geopolymers structure. The nano oxide composites were synthesised by adding different amounts of as-prepared metal oxide nanoparticles to the modified geoplymer to produce a hydrophobic photocatalyst composite with improved photocatalytic activity arising from the dispersion of the metal oxide nanoparticles in the external surfaces and interlayers of the geopolymer matrix. This method has the advantage of producing geopolymer composites with a stable pH which are more suitable for dye degradation studies. At concentrations >20 wt%, the photo-oxide component decreases the adsorption rate by blocking the active adsorption sites of the geopolymer. Under UV radiation, the composites remove the MB by a combination of adsorption and photodegradation, without deterioration of the geopolymer structure or the photoactive metal oxide component. In addition these studies show that the metal oxide-geopolymer nano composites have significantly improved photocatalytic activity compared with the oxide nanoparticles alone, because of the unique properties of these inorganic polymers. These results demonstrate that composites of nanosized Cu₂O particles and photoreactive TiO₂ in an aluminosilicate inorganic polymer matrix constitute new and novel materials with potential environmental protection applications to efficiently remove organic pollutants from water or the atmosphere.</p>

Features of Structural-Phase Transformations during Oxidation of Metals with Bulk Submicrocrystalline Structure and Fine Metal Powders

The oxidation processes for compact and powdery samples of titanium, copper, and molybdenum with different volume structure and dispersivity were studied using thermal analysis, electron microscopy, and X-ray diffraction. It is established that producing of metals with a modified structure under conditions of high-energy impact (severe plastic deformation, electric explosion of a thin wire) in accordance with intermediate annealing leads to an increase in the content of oxygen in the form of solid solutions and oxides; the oxide component’s share, form and localization within the material depend on physicochemical properties of both metal and oxide . It is shown that the structural-phase transformations of the oxide component during heating of fine-grained metals and powders have a significant effect on the parameters of the oxidation process of such materials. The thermally induced effects in the oxygen-containing components might play a critical role for the structure stability during long-term use of such materials under cyclic thermomechanical impacts.

Application of Silicon Dioxide as the Inert Component or Oxide Component Enhancer in ANFO

Non-ideal explosives with differing contents of silicon dioxide (silica or dioxosilane) added in the form of powder and gel were tested. Measurements of structure, crystallinity and morphology were performed by means of infrared spectroscopy (IR), X-ray diffraction (XRD) and scanning electron microscopy (SEM). IR and XRD analysis revealed a lack of SiO2 influence on the non-ideal explosive structure. SEM analysis indicated that all the surface deformations of ammonium nitrate(V) prill were filled by a thin fuel film layer on which SiO2 was present. The additional calculations of selected theoretical properties of non-ideal compositions were made using ZMWCyw software. Based on this, it was established that the optimum semimetal content was 1.0 wt.%. Blasting tests confirmed that the addition of 1.0 wt.% SiO2 to the Ammonium Nitrate Fuel Oil (ANFO) resulted in the lowest volume of post-blast fumes. Moreover, it was established that finer SiO2 powder cannot be used as the oxide component enhancer due to the inhibition of detonation reaction. SiO2 should be used only as an inert component.

Establishing patterns of the structural-phase transformations during the reduction of tungsten-containing ore concentrate with carbon

This paper reports a study into the phase composition and microstructure of tungsten ore concentrate after carbon-thermal reduction at different O:C ratios in the charge. This is required for determining those indicators that reduce tungsten loss through the sublimation of oxide compounds when processing ore concentrates, as well as when using reduced tungsten-containing doping additives. The study results have established that the reduced tungsten concentrate at the O:C ratio in the charge within the interval of 1.33‒2.30 contained the phases of W, W2C C, C, WO2. The microstructure demonstrated a spongy and disordered character. Together with W, the Mo, Si, Ca, Al impurities were present in the reduced products. The main elements identified at the sites studied had the following limiting content, % by weight: O – 5.01–17.32; C – 0.84–4.23; W – 61.21–86.78; Mo – 1.57–7.51; Si – 2.07–9.06; Ca – 1.34–11.30; Al – 0.27–0.40. The micro-inclusions at the examined surface areas acquired different complex shapes. There were traces of the process of caking between the particles. The analysis of the resulting data has shown that the most preferred ratio of O:C in the charge was 1.65. In this case, there is no lack of carbon and there is a predominance of W in the phase composition with a relatively little manifestation of the W2C phases, carbon, as well as the residual part of WO2. The post-reduction of the oxide component would occur during the doping process. The sponge structure contributes to a higher dissolution rate compared to standard tungsten ferroalloys. Lack of compounds with a relatively high propensity for sublimation does not require any special conditions to prevent the loss of tungsten in the gas phase, which increases the degree of assimilation of the target element

Identification and Characterization of Maitara Island Clay, North Maluku

Characterization and identification of Maitara Island clay have been carried out. This study aims to determine the types of minerals contained in the Maitara Island clay. The analytical methods used include X-Ray Fluorescence (XRF) to determine the chemical composition of Maitara Island clay, X-Ray Diffraction (XRD) for mineralogical analysis of Maitara Island clay, Fourier Transmission Infra Red (FTIR) to determine the types of vibrations that exist between the atoms in clay minerals from Maitara Island, and Scanning Electron Microscopy (SEM) to determine the morphology of clay minerals. XRF analysis showed that silica was the element found to dominate the clay minerals with a percentage of 40.79%. Moreover, the highest oxide component found was SiO2 with a percentage of 87.25%. XRD analysis indicated that the Maitara Island clay minerals are composed of montmorillonite, magmatite, aluminum oxide colondrum, cristobalite, lime, titanium oxide, and hematite. The results of FTIR analysis denoted the presence of silica as silanol and siloxane. SEM images showed angular grains which signified silica as the main component in the clay minerals of Maitara Island

Hemisyntheses and In-Silico Study of New Analogues of Carlina Oxide from Carthamus Caeruleus Roots.

Aim and Objective:: Nowadays, developing effective antibiotics for bacteria control has become difficult due to increased resistance to the available medicines in the market. Essential oils have very interesting biological properties; some of their components have very powerful antiviral and antibacterial properties. Carthamus caeruleus is a plant that has antibacterial and antioxidant activity due to the presence of an acetylenic compound, Carlina oxide. The aim of this work was to provide for the first time the chemical modifications to the structure of Carlina oxide and the in-silico study of these analogues. Materials and Methods:: The essential oil of Carthamus caeruleus was extracted by steam distillation in a Clevenger-type apparatus. Carlina oxide component was separated by column chromatography. Five new analogues were synthetized and identified by spectroscopic analyses (RMN, IR and SM). Molecular docking simulation study was performed using Molecular Operating Environment software (MOE) on three enzymes of bacterial origin (Streptococcus pyogenesis and Enterococcus faecalis). Results:: Five new compounds derived from Carlina oxide were synthesized (IM8-IM12), and their structures were characterized by infrared (IR), 1H and 13C nuclear magnetic resonance (NMR). The new synthesized compounds were evaluated as mSpeB, DHFR from Enterococcus faecalis and DNA gyrase inhibitors by a docking analysis using MOE. These results show interesting ligand interactions with the three enzymes, and the best result was attributed to the complexes formed with IM9, which had the lowest score. Conclusion:: In fact, these new compounds could lead to powerful approaches for the research and development of new antibiotics.

Biogeochemistry of Household Dust Samples Collected from Private Homes of a Portuguese Industrial City

The main objectives of the present study were to (i) investigate the effects of mineralogy and solid-phase distribution on element bioaccessibility and (ii) perform a risk assessment to calculate the risks to human health via the ingestion pathway. Multiple discriminant analysis showed that the dust chemistry discriminates between indoor and outdoor samples. The solid-phase distribution of the elements in indoor dust indicated that a large proportion of zinc, nickel, lead, copper, and cobalt is associated with an aluminum oxy-hydroxides component, formed by the weathering of aluminum silicates. This component, which seems to influence the mobility of many trace elements, was identified for a group of indoor dust samples that probably had a considerable contribution from outdoor dust. An iron oxide component consisted of the highest percentage of chromium, arsenic, antimony, and tin, indicating low mobility for these elements. The bioaccessible fraction in the stomach phase from the unified BARGE method was generally high in zinc, cadmium, and lead and low in nickel, cobalt, copper, chromium, and antimony. Unlike other potentially toxic elements, copper and nickel associated with aluminum oxy-hydroxides and calcium carbonates were not extracted by the stomach solutions. These trace elements possibly form stable complexes with gastric fluid constituents such as pepsin and amino acid. Lead had a hazard quotient >1, which indicates the risk of non-carcinogenic health effects, especially for children.

Thermodynamic modeling of metals reduction from B2O3-CaO-FeO-NiО melts by carbon monoxide and hydrogen

Thermodynamic modeling method have been used to describe the process of Iron and Nickel joint reduction from oxide melt of the B2O3-CaO-FeO-NiO system by Carbon monoxide and Hydrogen. Fractional inducing of reducing agent and periodic removal of metal gases from working body composition are applied in the method. The equilibrium states are determined for each unit portion of gas, and oxide component composition of the working body in each calculation cycle is taken from the previous data. Such approach is originality of the method. The approach gives possibility to bring the simulated processes closer to real technologies as well as to estimate reactions completeness in pyrometallurgical aggregates. The calculations were carried out accounting disproportionation of FeO into Fe and Fe3O4. It was shown that as a result of FeO disproportionation under neutral conditions (Ar), the resulting metallic Iron interacts with Nickel oxide to form ferronickel. As a result, the initial composition of the B2O3-CaO-FeO-NiO system variation, take place. Additionally, Fe3O4 appears in the working body. The relationship of Iron and Nickel oxides contents in oxide melt, degrees of its reducing and composition of ferronickel formed depending on temperature and induced reducing agent are revealed. The Hydrogen quantity consumed for metal reducing, at which the same degree of Nickel metallization is achieved, is much less comparing to CO. However, the resulting ferroalloy has less Nickel content, which is associated with increase of reduced Iron content. The obtained information is useful for prognoses of thermal extraction processes acting during useful components extraction from oxide melts, for example, nonferrous metallurgy slag.

Advanced Structured of MgO Thin Film for Bio Applications

Extensive efforts to further promoting the Anti-Bacteria and structural properties of thin films to reach reliability and possibility of commercialization, the chemical Tri-metal oxide component was verification as Anti-Bacteria factor in this paper. Pure and mixed thin films of magnesium oxide MgO was prepared by evaporation assisted laser Nedmyum - YAG pulse Nd: YAG laser system, MgO enhanced by adding Ti and Se, at (0.5, 1, 1.5 and 2%) by weight percentage. After that, calcination is done at 400 °C for 30 min. Structural and anti-bacterial growth inspections were performed. Experimental results showed that structural properties have improved significantly with the development of a MgO thin films with tri-metal oxide; Magnesium titanium oxide Mg2TiO4 and Magnesium selenate MgSeO4 phases. Moreover, there has been an enhancement in anti-bacteria properties, which makes these thin films more reliable for protection against bacteria.