Estudos sobre a formação de sulfeto de carbono e redução de dioxido de enxofre em matrizes carbonaceas

Tese (doutorado) - Universidade Federal de Santa Catarina, Centro de Ciencias Fisicas e MatematicasEstudo mecanístico da formação de sulfeto de carbono sobre diversas fontes de carbono, considerando aspectos cinéticos, caracterização de complexos C-S e efeitos catalíticos de sais inorgânicos. Redução de SO2 sobre matrizes carbonosas com formação de enxofre elementar ou CS2 considerando a conversão de carbono, cinética, distribuição de produtos e efeito de sais inorgânicos

Catalise da reação de formação de sulfeto de carbono

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciencias Fisicas e MatematicasA reação entre vapores de enxofre diluídos em nitrogênio com coque catarinense para formar sulfeto de carbono, foi estudada em um micro-reator de quartzo na faixa de 700 - 900oC. Em condições de ordem zero a velocidade de aparecimento do sulfeto de carbono é catalisada por sais de metais alcalinos (LiNO3, NaNO3, KNO3, Na2CO3, K2CO3 e Cs2CO3), alcalinos- terrosos (Ca(NO3)2) e de metais de transição (Ni(NO3)2 e Ti(oxalato)2). Estes sais foram incorporados ao coque por impregnação

Modeling volatile organic compounds (voc`s) adsorption onto cup-stacked carbon nanotubes (cscnt) using the linear driving force model

Modeling volatile organic compounds (voc`s) adsorption onto cup-stacked carbon nanotubes (cscnt) using the linear driving force model. Volatile organic compounds (VOC`s) are an important category of air pollutants and adsorption has been employed in the treatment (or simply concentration) of these compounds. The current study used an ordinary analytical methodology to evaluate the properties of a cup-stacked nanotube (CSCNT), a stacking morphology of truncated conical graphene, with large amounts of open edges on the outer surface and empty central channels. This work used a Carbotrap bearing a cup-stacked structure (composite); for comparison, Carbotrap was used as reference (without the nanotube). The retention and saturation capacities of both adsorbents to each concentration used (1, 5, 20 and 35 ppm of toluene and phenol) were evaluated. The composite performance was greater than Carbotrap; the saturation capacities for the composite was 67% higher than Carbotrap (average values). The Langmuir isotherm model was used to fit equilibrium data for both adsorbents, and a linear driving force model (LDF) was used to quantify intraparticle adsorption kinetics. LDF was suitable to describe the curves

Structural, optical and photocatalytic properties of erbium (Er3+) and yttrium (Y3+) doped TiO2 thin films with remarkable self-cleaning super-hydrophilic properties

The self-cleaning and super hydrophilic properties of pristine TiO2 and of TiO2 doped with Er3+ or Y3+ transparent thin films deposited onto glass substrates were investigated. The thin films prepared by multiple dipping and drying cycles of the glass substrate into the pristine TiO2 sol and Er3+ or Y3+-doped TiO2 sol were characterized by X-ray diffraction, UV-vis spectrophotometry, and atomic force microscopy (AFM). The self-cleaning photocatalytic activity of the thin films towards the removal of oleic acid deposited on the surface under UVA irradiation was evaluated. A remarkable enhancement was observed in the hydrophilic nature of the TiO2 thin films under irradiation. The optical properties and wettability of TiO2 were not affected by Er3+ or Y3+ doping. However, the photocatalytic degradation of leic acid under UVA irradiation improved up to 1.83 or 1.95 fold as the Er3+ or Y3+ content increased, respectively, due to the enhanced separation of the photogenerated carriers and reduced crystallite size. AFM analysis showed that the surface roughness increased by increasing the Er3+ or Y3+ content due to the formation of large aggregates. This in turn contributes to the increase of the active surface area enhancing the photodegradation process. This study demonstrates that TiO2 doped with low amounts of Er3+ or Y3+ down to 0.5 mol% can produce transparent, super-hydrophilic, thin film surfaces with remarkable self-cleaning properties

Economical and technological aspects of copper removal from water using a geopolymer and natural zeolite

This study reports the efficiency of a synthesized eco-friendly geopolymer (7.5 wt% of coal fly ash incorporated into its composition) as an adsorbent for the removal of Cu(II) from an aqueous solution and a real water matrix. The results obtained were compared with a commercial natural zeolite used as an adsorbent of toxic metals in Brazil. The effect of the operating conditions on the adsorption kinetics and equilibrium were studied in a finite bath and in a fixed bed column. The adsorption kinetics curves obey the pseudo-first-order model for both materials. The geopolymer presented higher adsorption capacity than zeolite, and values for theq(max_geo)/q(max_zeo)ratio were 1.13, 1.92, and 2.56 at temperatures of 25, 40, and 55 degrees C, respectively. The isotherms obtained in the thermodynamic study are favorable and spontaneous adsorption process. The adsorption processes are endothermic. The geopolymer showed higher adsorption efficiency than the zeolite in a fixed-bed column, and even with the presence of substances in the natural water sample, the Cu(II) removal capacity of the geopolymer is 3-4 times higher than that of the zeolite. A cost analysis was also performed, the geopolymer was found to be a more economical adsorbent than the commercial zeolite2317CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQCOORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPES405.223/2018-8sem informaçã