In many applications, such as fuel storage tanks and fuel lines, galvanized steel is used as a construction material which comes into contact with biodiesel. Considering that biodiesel is more corrosive than petroleum diesel, studies that aim to increase the corrosion resistance of galvanized steel in this environment are required. The present work investigates how the chemical conversion treatment in the oxalic acid solution affects the corrosion resistance of galvanized steel in soybean biodiesel (B100) in the absence and presence of the natural additives the extract the turmeric, clove, ginger, stone breaker, and rosemary. The results obtained indicate that the conversion treatment reduces the corrosion rate of the zinc coating in soybean biodiesel in the absence and presence of additives, and in this condition the effect of the conversion treatment depends on the additive used. applications lines diesel required B100 B (B100 turmeric clove ginger breaker rosemary B10 (B10 B1 (B1 (B

Abstract The use of natural additives in biodiesel has been investigated, however, there is limited information in the literature in relation to their influence on corrosion resistance and oxidative stability. This work aims to investigate the oxidative stability of biodiesel and the corrosion resistance of carbon steel (AISI 1020) in contact with soybean biodiesel solutions (B100) in the presence and absence of natural additives such as: rosmarinic acid, curcumin, gingerol, eugenol, thymol and quercetin. Corrosion and microscopy tests were used to assess corrosion resistance. The Rancimat technique was used to study oxidative stability. The results obtained indicate that curcumin was the best additive in relation to oxidative stability, while rosmarinic acid showed better performance in inhibiting corrosion. The effect of these substances is related to the presence of phenolic compounds or the existence of oxygen in its molecular structure.

The present paper concerns to predict the sulfur concentration in biodiesel/diesel blends in the range of 5-100 mg L-1 of sulfur using spectrofluorimetry and partial least squares multivariate calibration (PLS). The calibration set consisted of samples with 10 and 20% (B10 and B20) of biodiesel in diesel with sulfur addition of 5-100 mg L-1. Two PLS models were constructed, one to predict the concentrations of sulfur in B10 blends that presented coefficient of determination (R2) values of 0.9867377 and 0.9801064, respectively, for calibration and validation. The other PLS model predict the concentrations of sulfur in B20 that presented R2 values of 0.9949219 and 0.8573713, respectively, for calibration and validation. Therefore, the models showed adequate efficiency to predict changes in the concentration of sulfur in biodiesel/diesel blends B10 and B20.

In order to separate and identify functional groups of molecules responsible for fluorescence compounds present in biodiesel, a column chromatography coupled with infrared spectroscopy and multivariate analysis was performed. A biodiesel sample was packed in a chromatographic column and the fractions obtained were used to perform the analyses. Before undergoing the separation process, the biodiesel sample was analyzed by light emitting diode (LED)-induced fluorescence and compared its spectrum with β-carotene and soybean oil patterns. The low cost and speed of analysis suggest that this technique can be used in the separation of biodiesel substances. The fluorescence emission spectra allowed identifying molecules such as β-carotene, in which the spectrum of its pattern exhibited fluorescence within a region ranging from 500 to 700 nm and chlorophyll molecules. When soybean oil is excited at around 405 nm, it features a fluorescent emission band within the region of 670 nm, which reveals the presence of chlorophyll. Infrared spectroscopy coupled with principal component analysis allowed to discriminate the fractions and to identify the functional groups of compounds present in the sample.

Biodiesel consists of long-chain fatty acid esters and it presents relatively inert behavior right after its production. However, structural changes occur during its storage, as this fuel has low oxidative stability, fact that increases its corrosivity. The problem of corrosion has become increasingly relevant due to the Government's policy of setting a gradual increase in the percentage of biodiesel added to diesel. The current study evaluated the effectiveness of three natural products to work as corrosion inhibitor in biodiesel. The evaluation was done by means of immersion tests and electrochemical impedance spectroscopy. Results showed that it is possible to reduce biodiesel influence on carbon steel corrosion and that it can be extend to other metals used in automotive engines.

<p>This paper describes a simple and rapid methodology for determining the content of adulterants in diesel by the integration of fluorescence spectra. The procedure consists of constructing analytical curves using the concentrations of each adulterant in diesel and the relative change in the fluorescence area of each blend with respect to the fluorescence area of the diesel. The results indicated that the proposed method can be used to determine adulterants such as non-transesterified residual cooking oil, kerosene, and turpentine in diesel. The detection limits were 3, 4 and 5% for non-transesterified residual cooking oil, kerosene and turpentine in diesel, respectively. The method was also successfully used to determine the non-transesterified residual cooking oil content in B5 biodiesel-diesel blend (5% biodiesel) in the range of 0-70%, with a limit of detection of 4%.</p>

Approximately 600-700 species of Ipomoea, Convolvulaceae, are found throughout tropical and subtropical regions of the world. Several of those species have been used as ornamental plants, food, medicines or in religious ritual. The present work reviews the traditional uses, chemistry and biological activities of Ipomoea species and illustrates the potential of the genus as a source of therapeutic agents. These species are used in different parts of the world for the treatment of several diseases, such as, diabetes, hypertension, dysentery, constipation, fatigue, arthritis, rheumatism, hydrocephaly, meningitis, kidney ailments and inflammations. Some of these species showed antimicrobial, analgesic, spasmolitic, spasmogenic, hypoglycemic, hypotensive, anticoagulant, anti-inflammatory, psychotomimetic and anticancer activities. Alkaloids, phenolics compounds and glycolipids are the most common biologically active constituents from these plant extracts.

Total spectrofluorimetry associated to Principal Components Analysis (PCA) were used to classify into different groups the samples of diesel oil, biodiesel, vegetal oil and residual oil, as well as, to identify addition of non-transesterified residual vegetable oil, instead of biodiesel, to the diesel oil. Using this method, the samples of diesel oil, mixtures of biodiesel in diesel and mixtures of residual oil in diesel were separated into well-defined groups.

The chloroform extract of aerial parts of Ipomoea subincana was submitted to different chromatographic procedures which afforded methyl caffeate, ethyl caffeate, methyl 3,4-dimethoxycinnamate, lupeol, alpha-amyrin, beta-amyrin, 3-beta-O-beta-D-glycopiranosyl-sitosterol, beta-sitosterol, stigmasterol, scopoletin, aromadendrane-4beta,10alpha-diol, n-docosyl-cis-p-coumarate and n-icosyl-trans-p-coumarate, vanilin, cinamic acid and vanillic acid. However, from the ethyl acetate extract besides quercetin and 3-O-beta-D-glycopiranosyl-quercetin were isolated methyl 4-O-E-feruloyl-5-O-E-caffeoyl-quinate, methyl 3,5-di-O-E-caffeoyl-quinate and methyl 4-O-E-caffeoyl-quinate. The structures of the compounds were established on the basis of spectral data.

This work describes the phytochemical study of hexane extracts from the stem of Maprounea guianensis. Besides 3-oxo-21alpha-H-hop-22(29)-en (moretenone), beta-sitosterol, lupenone and lupeol, a mixture of dodecosyl, tetracosyl, hexacosyl, octacosyl and triacontyl ferulates was also isolated, as well as 3-beta-acetoxy-lup-20(29)-en-28-oic acid, 3beta-O-trans-p-coumaroyl-lup-20(29)-en-28-oic acid and 3beta-O-trans-p-coumaroyl-urs-12-en-28-oic acid. The structures of these compounds were established by spectroscopic analysis.