Search Results

You are looking at 1 - 6 of 6 items for

  • Author or Editor: R. Candeia x
  • Refine by Access: All Content x
Clear All Modify Search
Journal of Thermal Analysis and Calorimetry
Authors: R. Candeia, J. Freitas, M. Souza, Marta Conceição, Iêda Santos, L. Soledade, and A. Souza

Abstract  

The most feasible alternative among fuels derived from biomass seems to be the biodiesel, having the required characteristics for a total or partial substitution of diesel oil. Therefore, the aim of this work is to evaluate the thermal and rheological behavior of the blends of diesel with the methanol biodiesel obtained from soybean oil, using B5, B15 and B25 blends. All thermogravimetric curves exhibited one overlapping mass loss step in the 35–280C temperature range at air atmosphere and one step between 37–265C in nitrogen. The rheological study showed a Newtonian behavior (n=1) for all blends.

Restricted access
Journal of Thermal Analysis and Calorimetry
Authors: Camila Xavier, R. Candeia, M. Bernardi, S. Lima, E. Longo, C. Paskocimas, L. Soledade, A. Souza, and Iêda Santos

Abstract  

Magnesium and zinc ferrites have been prepared by the polymeric precursor method. The organic material decomposition was studied by thermogravimetry (TG) and differential thermal analysis (DTA). The variation of crystalline phases and particle morphology with calcination temperature were investigated using X-ray diffraction (XRD) and scanning electronic microscopy (SEM), respectively. The colors of the ferrites were evaluated using colorimetry. Magnesium ferrite crystallizes above 800°C, presenting a yellow- orange color with a reflectance peak at the 600–650 nm range, while zinc ferrite crystallizes at 600°C, with a reflectance peak between 650–700 nm, corresponding to the red-brick color.

Restricted access
Journal of Thermal Analysis and Calorimetry
Authors: F. L. Macedo, R. A. Candeia, L. L. M. Sales, M. B. Dantas, A. G. Souza, and M. M. Conceição

Abstract

Searching for other alternative sources, which are not part of the food chain, and which are able to supply the biofuel market is a promising option. In this context, it has been searched to investigate the oiticica oil, approaching its availability to the biodiesel synthesis, as well as its thermal stability. Few works retreat parameters such as: the optimization of the biodiesel synthesis, its physical–chemical properties, and thermal parameters etc. The characterization results revealed that the oil showed very high kinematic viscosity, and acidity value around 13 mg KOH/g, requiring a pre-treatment. To reduce the acid in the oil, it has been done the esterification of oil, which was studied in different molar ratios oiticica oil/ethanol (1:9) and 2.0% catalyst, in order to get the best reduction the index of acidity. The lowest level of acidity of the oil obtained after the esterification was 4.4 mg KOH/g. The reaction rate for the synthesis of biodiesel, compared to the initial mass of oiticica oil ester was 85%. This income can be overcome by pursuing an even smaller reduction of acid value of biodiesel oiticica. The acid value of biodiesel was 1.8 mg KOH/g. The results have revealed that the oiticica oil and biodiesel are stable at 224 and 179 °C, respectively.

Restricted access
Journal of Thermal Analysis and Calorimetry
Authors: M. A. F. Souza, R. A. Candeia, S. J. G. Lima, M. R. Cassia-Santos, I. M. G. Santos, E. Longo, and A. G. Souza
Restricted access
Journal of Thermal Analysis and Calorimetry
Authors: M. A. F. de Souza, A. G. Souza, R. A. Candeia, D. M. A. Melo, L. E. B. Soledade, M. R. C. Santos, I. M. G. Santos, S. J. G. Lima, and E. Longo
Restricted access
Journal of Thermal Analysis and Calorimetry
Authors: R. A. Candeia, F. S. M. Sinfrônio, T. C. Bicudo, N. Queiroz, A. K. D. Barros Filho, L. E. B. Soledade, I. M. G. Santos, A. L. Souza, and A. G. Souza

Abstract

Biodiesel oxidation is a complex process widely influenced by the chemical composition of the biofuel and storage conditions. Several oxidation products can be formed from these processes, depending on type and amount of the unsaturated fatty acid esters. In this work, fatty acid methyl and ethyl esters were obtained by base-catalyzed transesterification of soybean oil and physicochemically characterized according to standards from ASTM, EN, and ABNT. The thermal and oxidative stabilities of biodiesel samples were investigated during the storage process by pressure differential scanning calorimetry (PDSC) and by viscosity measurements. Absolute viscosities of biodiesels after accelerated aging were also determined. The viscosity increased as the aging temperature and time were raised. The results showed that oxidation induction can occur during storage, decreasing the biodiesel stability. PDSC analysis showed that during storage under climate simulation the values of high-pressure oxidative induction times (HPOIT) were reduced for both FAEE and FAME.

Restricted access