Impedimetric D-Xylose and D-Arabinose sensors was development from composite electrodes of graphite and histological paraffin, modified with functionalized multi-walled carbon nanotubes (FMWCNTs) based on molecular imprinted poly-ophenylenediamine (poly-o-PD). The contribution of this work was not only the development of a D-xylose and D-Arabinose MIP impedimetric sensor with good performance, but also the electrodeposition method for FMWCNTs onto surface of graphite composites electrodes with ease of control and reproducibility of the electrodeposition process. The sensors were characterized by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), field emission gun scanning electron microscopy (FEG-SEM) and RAMAN spectroscopy. The MIPs sensors for the pentoses have good selectivity, sensitivity in the concentration range of 1.0 × 10 −11 to 1.0 × 10 −10 mol l −1 with limit of detection (LOD) of 4.50 × 10 −12 mol l −1 for D-Xylose and 4.25 × 10 −12 mol l −1 for D-Arabinose. MIPs was applied to determination of pentoses in samples of sugarcane bagasse hydrolysates using the standard addition method and validated by recovery study, which presented satisfactory results between 92.9% and 115.5%.

The sensors modified carbon nanotubes and molecularly imprinted polymers are an excellent choice for the determination of D-arabinose, because they have high selectivity and sensitivity for analysis. This allows the control and optimization of the second generation ethanol production process, given the clear understanding of the chemical changes that occur through the hydrolysis of lignocellulosic biomass. For this reason, the present work presents a chemical study of the functional groups of the chemical species present on the sensor surface by the Fourier transform infrared spectroscopy (FT-IR) technique and a morphological analysis by the scanning electron microscopy (SEM) technique.

Composites graphite/reduced graphene oxide electrodes modified with nickel oxy-hydroxide nanoparticles electrodeposited onto electrode surface were developed and applied for the oxidation of ethanol and 2-propanol in alkaline medium. Ni(OH)2 nanoparticles was electrosynthesized in two steps by cyclic voltammetry. Firstly, nickel(II) hexacyanoferrate nanoparticles were electrodeposited, and subsequently Ni(OH)2 was performed in 0.50 mol l−1 NaOH solution. This facile controlled-synthesis method for electrosynthesis of Ni(OH)2 nanoparticles has excellent reproducibility in the manufacture of the modified electrodes. The composite electrodes were characterized by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), field emission gun scanning electron microscopy (FEG-SEM). Electrooxidation of ethanol and propanol were performed in an alkaline medium, and composite electrode modified with Ni(OH)2 nanoparticles promoted the alcohols electrooxidation. The electrodes showed a linear current relationship as a function of the concentration of the alcohols, and the current density obtained by cyclic voltammetry (50 mV s−1) for ethanol was 6.6 mA cm−2 and for 2-propanol was 13.1 mA cm−2 in a solution of 0.1 mol l−1 of NaOH.

In order to mitigate the impacts caused by the rampant consumption of fossil fuels, many countries are investing in the development and optimization of alternatives that minimize dependence on fossil energy. The second generation of ethanol (2G), characterized by its relevant production potential, is considered a good alternative, which can be produced from sugarcane bagasse. Therefore, it is extremely important to evaluate the efficiency of 2G ethanol production processes, mainly in the compositional analysis of hydrolysates from the pre-treatment of lignocellulosic biomass, to promote greater production. Thus, the development of electrochemical sensors composed of graphite/paraffin composite electrodes coated with multi-walled carbon nanotubes (MWCNTs) modified with molecularly imprinted polymers (MIPs) are an excellent option for carrying out rapid analyzes. Due to the highly sensitive electrical properties of the MWCNTs and the molecular impression of the polymers that allow a high affinity with the model molecule, the sensor has high selectivity, good sensitivity and reproducibility for the determination of ferulic acid. For this reason, the present work, using the Scanning Electron Microscopy (SEM) and Cyclic Voltammetry (CV) technique, presents remarkable morphological characteristics of the sensor surface and its electrochemical behavior in relation to the electropolymerization process and speed increase of the scan.

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Com o crescimento da população e o aumento da demanda por energia surge a necessidade de desenvolvimento de fontes alternativas energia. O biometano, obtido a partir da purificação do biogás, que pode ser retirado da decomposição resíduos sólidos urbanos, presente em quantidades abundantes em muitas cidades brasileiras, tem se despontado como uma interessante alternativa a fim de complementar a utilização combustíveis gasosos, visto que o principal combustível utilizado atualmente é o gás natural, de origem fóssil e com impactos ambientais negativos em sua extração.  Este trabalho promove a análise da viabilidade energética e ambiental da utilização do biometano para a injeção na rede de gás de natural, a partir de ferramentas de simulações computacionais. Os resultados obtidos, indicam que as emissões dos gases da combustão do gás natural e do biometano são praticamente equivalentes e, a diferença nos valores de temperatura de chama entre os combustíveis é de cerca de 7,1%. Assim, a inserção do biometano na rede de gás natural, além de não implicar no aumento de impactos ambientais também não promove perdas significativas nas características energéticas da mistura.