Joner Oliveira Alves

Microstructural Analysis of Carbon Nanomaterials Produced from Pyrolysis/Combustion of Styrene-Butadiene-Rubber (SBR)

Styrene-Butadiene-Rubber (SBR) is a synthetic rubber copolymer used to fabricate several products. This study aims to demonstrate the use of SBR as feedstock for carbon nanomaterials (nanofibers and nanotubes) growth, and therefore to establish a novel process for destination of waste products containing SBR. A three stage electrically heated flow reactor was used. Small pellets of rubber were pyrolyzed at a temperature of 1000 °C. The pyrolyzates were mixed with oxygen-containing gases and were burned. The products of combustion were used to synthesize the carbon nanomaterials (CNMs) at the presence of a catalyst. CNMs have a wide range of potential applications due to their extraordinary mechanical, thermal and electrical properties. Produced materials were characterized by SEM and TEM, whereas combustion products were assessed using GC. Results showed that CNMs with outer diameters of 30-100 nm and lengths of about 30 µm were formed. Therefore, it was demonstrated that waste products containing SBR can be used to generate CNMs which are value-added products of intense technological interest.

Síntese de nanomateriais de carbono a partir do resíduo de milho (DDGS)

The worlds largest ethanol producer (USA) uses corn as feedstock. DDGS (distillers dried grains with solubles) is the main waste generated from this process (around 32 million t/year). DDGS samples were pyrolyzed at 1000 oC in a furnace with controlled atmosphere. The effluent was channeled to a second furnace, in which catalyst substrates were placed. Chromatographic analysis was used to evaluate the gaseous effluents, showing that the catalyst reduced hydrocarbon emissions. The solid products formed were analyzed by SEM and TEM. Graphitic structures and carbon nanofibers, 50 µm in length and with diameters of 80-200 nm, were formed.

Biolixiviação em reatores para tratamento do minério de cobre proveniente da região de Carajás (PA)

The bioleaching consists of ore leaching from the oxidizing bacteria, such as Acithiobacillus ferrooxidans. This study aimed to evaluate the bioleaching process of chalcopyrite in reactors with two different ores, one sulfide and one oxidized, from the region of Carajás (PA), in Brazil. A test conducted in tanks, in batch, containing 3kg of ore per 100 days. Mineralogical characterizations were performed by XRD and chemical analysis by EDXRF. Measurement of pH and Eh were performed daily, and collected samples for determination of copper extraction, by EDXRF. The results highlighted the similar behavior of Eh and distinguished to pH, because of their composition. On the 100 day, the sulfide ore sample presented 0.74% copper extraction, but the process being still active. The oxidized ore sample presented 18.35% of extraction on the 60 day, stabilizing from then on, and the process virtually ended on the 100 day.

RESÍDUO DO CORTE DE GRANITO: INOVAÇÃO TECNOLÓGICA PARA A DESTINAÇÃO FINAL

The granite processing market is one of the most promising business areas of the mineral sector, with an average growth of the world production of about 6% per year. The granite extraction generates residues in the form of powder rock of 20-25 wt.% of the total benefited. The granite dust must be carefully managed since it can cause siltation of rivers and human health risks. This paper presents two routes for the final destination of this waste: the vitrification process aiming the production of fibers for thermo-acoustic insulation, and the magnetic separation in order to recover the steel grit. Results showed that the forms of treatments presented are economically and ecologically viable since they represent a cost reduction in the waste disposal, and also provide the production of new materials with commercial value.

ANÁLISE E CONTROLE DOS HIDROCARBONETOS GERADOS NA COMBUSTÃO DOS RESÍDUOS DE PET

Brazilian production of PET (polyethylene terephthalate) in 2010 was of 505,000 tones. The PET waste may be used to generate energy by controlled burning. In this study, emissions of light hydrocarbons generated during combustion of these wastes are characterized. Samples of post-consumer PET bottles were inserted in an electric furnace at temperatures of 600, 800 and 1000°C under an atmosphere of 15% O2 and 85% N2. The effluents were subjected to a SiC filter and channeled into the second furnace at 1000°C. Stainless steel meshes were placed in the second furnace in order to work as catalyst. Gas chromatography is used to evaluate the effluent with and without the catalyst use, wherein is showed a significant reduction in the emissions using the meshes. Results allow a characterization of the hydrocarbons generated during the controlled burning of PET waste providing information for control and recovery of these gases emissions.

Síntese de nanotubos de carbono a partir do bagaço da cana-de-açúcar

The traditional sugar production associated with the growing ethanol production makes the sugarcane industry one of the main segments of the Brazilian economy; together the Brazilian industries of sugar and ethanol processed about 630 million tons of sugarcane in 2009, which generated approximately 142 million tons of bagasse. This work presents an economically and environmentally viable solution for the bagasse disposal through the controlled burn associated with the synthesis of carbon nanotubes (CNTs), materials that have a wide range of potential technological applications due to its exceptional properties. The pyrolysis process at 1000°C associated with a catalyst system were used to recover the generated gases as raw material for the synthesis of CNTs. Gaseous emissions were analyzed by chromatography and the produced materials were characterized with the use of SEM, TEM, TGA and Raman spectroscopy. Results showed that the catalyst application resulted in the reduction of gaseous emissions. Carbon nanotubes with lengths of 10-40 µm and diameters in the range of 20-50 nm were produced.