Ivon Pinheiro Lôbo

Biodiesel: parâmetros de qualidade e métodos analíticos

The establishment of quality standards for biodiesel was a key step to win the confidence of the market and the automotive industry, thus ensuring the success of the new fuel. In this review are presented standard methods and other analytical methods suggested for analysis of biodiesel. The methods of analysis were divided into groups according to information that may be provided on the contaminants from the raw material of the production process, the molecular structures of biodiesel and its degradation during storage.

2-(2-Thiazolylazo)-p-cresol(TAC) as a Reagent for the Spectrophotometric Determination of Lead(II)

Abstract The reaction between lead(II) and 2-(2-Thiazolylazo)-p-Cresol(TAC) in the presence of TERGITOL NPX (4 mg/ml) at an apparent pH 9.0–10.0 results in an intensely colored complex which is stable for at least 4 hr. The composition of the complex is 1:2 cation: TAC and the log of the formation constant is 11.92 ± 0. 40. Beers law is obeyed up to 6.0μg.ml−1 of lead(II) at 650nm. The apparent molar absorptivity at 650 nm is 2.07 × 104 1. mole−1.cm−1 and the detection limit was obtained as 10.0 ng.ml−1 of lead(II). The method is applied to determination of lead(II) in copper-base alloy.

ESTs from Seeds to Assist the Selective Breeding of Jatropha curcas L. for Oil and Active Compounds.

We report here on the characterization of a cDNA library from seeds of Jatropha curcas L. at three stages of fruit maturation before yellowing. We sequenced a total of 2200 clones and obtained a set of 931 non-redundant sequences (unigenes) after trimming and quality control, ie, 140 contigs and 791 singlets with PHRED quality ≥10. We found low levels of sequence redundancy and extensive metabolic coverage by homology comparison to GO. After comparison of 5841 non-redundant ESTs from a total of 13193 reads from GenBank with KEGG, we identified tags with nucleotide variations among J. curcas accessions for genes of fatty acid, terpene, alkaloid, quinone and hormone pathways of biosynthesis. More specifically, the expression level of four genes (palmitoyl-acyl carrier protein thioesterase, 3-ketoacyl-CoA thiolase B, lysophosphatidic acid acyltransferase and geranyl pyrophosphate synthase) measured by real-time PCR proved to be significantly different between leaves and fruits. Since the nucleotide polymorphism of these tags is associated to higher level of gene expression in fruits compared to leaves, we propose this approach to speed up the search for quantitative traits in selective breeding of J. curcas. We also discuss its potential utility for the selective breeding of economically important traits in J. curcas.

Simultaneous spectrophotometric determination of nickel and iron in copper-base alloy with bromo-PADAP

The reaction of nickel (II) with Br-PADAP, in the presence of tergitol NPX surfactant, forms a complex with absorption peaks at 520 and 560 nm. The iron(II)-Br-PADAP system at the same conditions forms a chelate with absorption peaks at 560 and 748 nm. This allows the simultaneous spectrophotometric determination of nickel and iron by measuring the absorbance at 560 and 748 nm. The proposed method, at ph 4.0-5.7, shows a molar absorptivity of 1.22 x 10(5)l . mole(-1) . cm(-1) for nickel at 560 nm and 8.20 x 10(4)l . mole(-1) . cm(-1) at 560 nm and 3.35 x 10(4)l . mole(-1) . cm(-1) at 748 nm for iron(II). Beers law is obeyed up to 0.40 mu/ml of nickel(II) and up to 0.65 mu/ml of iron(II). Thiosulphate as masking agent allows the simultaneous determination of iron and nickel in the presence of high concentrations of copper. The ethylene glycol 2-(2-amino-ethyl) tetracetic acid provides the elimination of many other interferences. The method has been applied successfully to the simultaneous determination of nickel and iron in reference samples.

Biodiesel de microalgas: avanços e desafios

Microalgae biomass has been described by several authors as the raw material with the greatest potential to meet the goals of replacing petroleum diesel by biodiesel while not competing with arable land suitable for food production. Research groups in different countries are seeking the most appropriate production model for productivity, economic viability and environmental sustainability. This review focused on recent advances and challenges of technology for the production of biodiesel from microalgae, including the procedures used to obtain biomass.

EspEctromEtria dE absorção atômica: o caminho para dEtErminaçõEs multi- ElEmEntarEs

This paper present an overview of way covered for the spectrometry of atomic absorption (AAS), tracing a line of the historical events in its development and its establishment as a multielement technique. Additionally, the efforts carried by through several researchers in the search for the instrumental evolution, the advances, advantages, limitations, and trends of this approach are related. Several works focusing its analytical applications are cited employing simultaneous multielement determination by flame (FAAS) and/or graphite furnace (GF AAS), and fast sequential multielement determination using FAAS are reported in the present review.

Synthesis and characterization of novel ZrO2-SiO2 mixed oxides

In this study the mixed oxides ZrO2-SiO2, were synthesized by the sol-gel method with a molar ratio of 95:5 (Si/metal) and characterized by X-ray diffraction, absorption-desorption of N2, Fourier transform infrared spectroscopy, thermal gravimetric analysis, temperature-programmed desorption of ammonia, and acidity test by titration. The synthesized materials, which are amorphous to X-rays, are composed of a mixture of micro- and mesopores. They show a higher acid strength than the separate oxides, indicating that the ZrO2 is highly dispersed in the silica matrix.

Jatropha Oil Transesterification and Byproducts

Meeting world’s energy demand is a growing challenge for our societies. Steadily rising oil prices and environmental questions associated with the combustion of fossil fuels have also urged humanity to seek new energy sources. The diversification of energy sources and the development of new technologies are necessary to guarantee future energy supply. In this context, biodiesel obtained from renewable resources is produced in great amount because of its environmental and social benefits. Considering the oil productivity, Jatropha curcas L. is one of the most efficient oil plants, only surpassed by microalgae, coconut, and oil palm. In addition, J. curcas produces non-edible oil that does not compete with food production and is a suitable source of feedstock for the production of biodiesel. Here, we attempted to review the different approaches and techniques used to generate biodiesel from J. curcas oil. The relation between the fatty acid composition of J. curcas oil and biodiesel quality is also addressed. The fatty acid composition in feedstock determines changes in the molecular structures of the esters in biodiesel that are related to important properties, such as viscosity, density, combustion efficiency and oxidative stability. Furthermore, we also reviewed the conversion routes of glycerol—the main co-product of biodiesel production that may add value to J. curcas biodiesel.