To increase oil sorption, polyurethane foams were modified with MoS2, ZnO grafting and/or hexadecanoic acid coating. The foams were characterized by Scanning Electron Microscopy + Energy Dispersive X-ray Spectroscopy and Contact Angle techniques. Three sorption tests were performed. In tests with 100% water, the ZnO-PC modification showed a reduction of 35.7% in the seawater sorption when compared to Un-PC. In tests with 100% oil, there was a 29-fold increase in sorption (more than 2803%) of S46 lubricant oil when Un-PC performance was compared with ZnO-PC. In tests on the multicomponent systems, the lowest seawater sorption was 0.01 ± 0.00 g.g-1 (HA-PC), 0.08 ± 0.01 g.g-1 (Un-PC), and 1.39 ± 0.02 g.g-1 (Un-PC) for 20W40 engine oil, S46 lubricating oil, and diesel, respectively. The highest oil sorption in the systems was 41.34 ± 1.02 g.g-1 (HA-PC), 32.81 ± 0.31 g.g-1 (MoS2-PC), and 14.78 ± 0.27 g.g-1 (ZnO-PC) for diesel, S46 lubricating oil, and 20W40 engine oil, respectively. The reuse tests indicated that even after 10 cycles, the ZnO-PC foam kept its sorption capacity unchanged. Post-consumer foams proved to be effective in the sorption of different oils spilled into seawater, especially those grafted with ZnO rods or impregnated with MoS2.

Abstract This work aimed to study nickel-based oxygen carriers (OC) for Chemical Looping Combustion (CLC) using H2 and CH4 as fuel. The reactivity and reaction kinetics of the OC were investigated, applying the shrinking core, nucleation and diffusion models in three dimensions, as well as whether the OC is thermodynamically favorable for the reaction. The results showed that the OC achieved high conversion for both fuels, proving to be quite reactive, while the fuel gas concentration and the temperature have a strong effect on the solids conversion. For the H2 combustion, the reaction rate can be described well by the shrinking core model, whereas for CH4 the nucleation model may better represent the experimental data. With respect to reactions that occur in the reduction reactor with the NiO/Ni redox system, it was observed that, for the investigated temperatures used in CLC, high values of the equilibrium constant were obtained, showing that practically complete conversion of the fuels is possible.

Reduction of silver cations followed by nanoparticle (Ag-NPs) synthesis is a model process to understand the reduction mechanism induced by a discharge over an aqueous surface, termed electrochemical plasma. This work aims at studying the silver reduction reaction steered by electrochemical plasma in the presence of other chemically active plasma-related interfaces, namely the plasma-gas and the liquid-gas interfaces. As no other plasma-induced species are able to reduce silver cations, the reduction of silver cations is employed as strategy to selectively detect the presence of hydrated electrons (e-h). The results demonstrate that the global rise of pH (increase in the content of OH-), observed for discharge in the helium gas phase, occurs in connection with the silver reduction, which is interpreted as a vivid experimental evidence of the second-order recombination reaction of the e h − 2 e aq − + 2 H 2 O → H 2 + 2 OH −. On the other hand, the global decrease of pH (increase in the content of H+) observed for discharge in mixed oxygen and nitrogen gas phase, is an event primarily driven by the Birkeland-Eyde process, and it is concomitant but spatially distinct from the electron injection. The acidification interferes in the NP formation, as NPs promptly dissolve in presence of HNO3. Only in complete suppression of the acidification, an experimental evidence of the reaction pathways for hydrated electron could be captured: e-h is competitively consumed through a scavenger-like reaction (reduction of silver cations in this work) and through the second-order recombination reactions of the e-h. The kinetic model proposed in this work further corroborates this interpretation.

ABSTRACT The robustness of the simulation of bioethanol concentration from sugarcane faces two major challenges: the presence of several minor components and the nonlinear behavior of vapor-liquid equilibrium (VLE) calculations. This work assesses the effect of simplifications to overcome these difficulties. From a set of seventeen substances, methanol, n-propanol, isobutanol, 2-methyl-1-butanol and 3-methyl-1-butanol were selected through the examination of the influence of each minor component on vapor-liquid equilibrium calculations of ethanol-water-third component systems. The selection procedure was based on Txy diagrams built using the modified Raoult's law. The influence of the ratio between the vapor phase fugacity coefficients and of the Poynting correction factor were verified. The accuracy of four correlations for vapor pressure was evaluated, and two functional-group activity coefficient models were scrutinized: the recent Functional-Segment Activity Coefficient (F-SAC) and the UNIFAC-Do model.

Abstract In order to inhibit natural gas hydrate formation, monoethyleneglycol (MEG) is usually injected into producing well heads. The MEG regeneration process is continuously performed at the platform. Scaling problems usually occur due to the presence of chlorides and carbonates. This work presents salt solubility data for the aqueous system with strontium carbonate, MEG and carbon dioxide. A specific analytical method was developed. Thus, experimental data for strontium carbonate (SrCO3) solubility at various carbon dioxide pressures are reported. Solubilities of SrCO3 in water were measured from 760 to 1610 mmHg at 278.15. 288.15. 298.15 and 323.15 K. For the mixed solvent (ms) conditions, solubilities were measured at 298.15 K and four isobars, i.e., 760, 1210, 1410 and 1520 mmHg. Experimental data were correlated and demonstrated to be accurate for thermodynamic modeling and process simulation.

Nickel ferrite/multi-walled carbon nanotubes (NiFe2O4/MWCNTs) composite has been rapidly synthesized via microwave irradiation technique. The structural properties of the product was investigated by X-ray diffraction (XRD), N2 adsorption/desorption isotherms, thermogravimetric analysis (TGA), Raman spectroscopy and, scanning electron microscopy (SEM). Catalytic behavior of the composite material on the advanced photo-Fenton degradation of Amaranth dye was evaluated. The synthesis conditions employed on the microwave system were: temperature (235 °C), power (500 W), pressure (600 psi) and irradiation time (30 min). Characterization results showed the formation of hybrid material, containing a predominantly microporous structure, with surface area and total pore volume of 54 m2 g-1 and 0.2249 cm3 g-1, respectively. The composite exhibited higher catalytic activity compared to the pure NiFe2O4, reaching 100% of decolorization at 60 min of reaction, which can be attributed to a synergism between NiFe2O4 and MWCNTs. Therefore, NiFe2O4/MWCNTs composite can be used as a promising photo-Fenton catalyst to degrade Amaranth dye from aqueous solutions.

RESUMO: Nesse trabalho, objetivou-se recuperar o óleo presente na borra oleosa por processo de extração, a fim de reutilizá-lo como combustível. Foram aplicados dois planejamentos experimentais: fatorial fracionado e Doehlert. Através da caracterização da borra oleosa (análises físico-químicos, elementar CHN e S, orgânicas e inorgânicas), constatou-se que a borra oleosa utilizada é constituída de 36,2% de óleo, 16,8% de cinzas, 40% de água e 7% de compostos voláteis. A eficiência média do processo de extração foi 70%. Entretanto, a análise estatística mostrou que o modelo quadrático não se ajustou bem ao processo, devido à complexidade do material estudado. Por outro lado, aplicando-se a modelagem de RNA, o coeficiente de determinação foi de 87,5%, mostrando-se bastante satisfatório.

ABSTRACT: This work aimed to recover the oil present in oily sludge by extraction process in order to reuse it as fuel. Two experimental designs were applied: fractional factorial and Doehlert. Through characterization of the oily sludge (physico-chemical analysis, CHN and S elemental, inorganic and organic), it was found that the oily sludge used consists of 36.2% oil, 16.8% ash, 40% water and 7% volatile compounds. The efficiency obtained in the oil extraction process was 70%, in average. However, statistical analysis showed that the quadratic model did not satisfactorily the process due to the complexity of the studied material. By the other hand, applying ANN the coefficient of determination became 87.5% that is quite satisfactory.

Este estudio investigó la influencia de NaCl sobre el punto de niebla de los tensioactivos polietoxilados de la familia de polietoxilatos de alcohol laurílico y polietoxilatos de nonilfenol. Se representaron gráficamente las curvas de equilibrio líquido-líquido de los sistemas acuosos con tensioactivos anteriormente mencionados con presencia de NaCl, surgiendo los parámetros termodinámicos basados en el modelo de Flory-Huggins. El uso del método visual determinó el punto de niebla. Se prepararon soluciones con concentraciones de surfactante entre 0,5 y 20% (por peso) y NaCl entre 4,9 y 12,1% (por peso). La sal tenía un efecto salino, disminuyendo la solubilidad surfactante en agua. Además, el punto de niebla disminuyó al aumentar la concentración de NaCl. El modelo de Flory-Huggins describió satisfactoriamente los datos experimentales para todas las misturas acuosas de surfactante + NaCl estudiadas.

In this study, the influence of NaCl on the cloud point of polyethoxylate surfactants from the family of lauryl alcohol polyethoxylates (C12EOn) and nonylphenol polyethoxylates (NPEOn) was investigated. Liquid-liquid equilibrium curves of the aforementioned aqueous surfactant systems with the presence of NaCl were plotted and thermodynamic parameters based on the Flory-Huggins model were obtained. The visual method was used to determine the cloud point. Solutions containing surfactant concentrations between 0.5 and 20% (by weight) and NaCl between 4.9 and 12.1% (by weight) were prepared. Salt had a salting-out effect, decreasing surfactant solubility in water. Furthermore, the cloud point decreased with an increase of NaCl concentration. The Flory-Huggins model satisfactorily described the experimental data for all surfactant + NaCl aqueous mixtures studied.

The production of metallic titanium (Ti) through the reduction of titanium oxide (TiO2) by aluminothermic reduction technique, using hydrogen plasma to trigger the reaction has been investigated. Titanium oxide and aluminum powders were previously processed by high energy grinding during 4, 6 and 10h. Also, a thermal analysis study was done to know the temperature for the aluminothermic process in TiO2-Al mixtures. The product obtained was characterized by X-ray diffraction and scanning electron microscopy and Rietveld method was used in the microstructure refinement. The results show that is possible too btain a titanium rich compound through the hollow cathode plasma technique.

Se ha investigado la producción de titanio metálico (Ti) mediante de la reducción de óxido de titanio (TiO2) por técnica de reducción aluminotérmica, usando plasma de hidrógeno como desencadenante de la reacción. El polvo de TiO2y Al utilizados se procesaron previamente por molienda de alta energía durante 4, 6 y 10 h. Se realizó también un estudio de análisis térmico, con el objetivo de conocer la temperatura de reacción para el proceso aluminotérmico de la mezcla TiO2-Al. El producto obtenido fue caracterizado mediante difractometría de rayos y microscopia electrónica de barrido, y se usó el método Rietveld para el refino en la determinación de la estructura. Los resultados comprueban la existencia de titanio metálico en el producto de la reacción aluminotérmica, cuando se utiliza el proceso de plasma.