Gustavo G. Shimamoto

Separation of the Glycerol-Biodiesel Phases in an Ethyl Transesterification Synthetic Route Using Water

Biodiesel is obtained by the transesterification of vegetable oil (or fat) and alcohol, with methanol being the most used alcohol. Methanol can be replaced by ethanol; however, this alcohol acts as a surfactant in the reaction mixture, promoting a stable dispersion of the glycerol in biodiesel, which hinders the separation of the glycerol-biodiesel phases. In this study, it was found that the addition of 1% v/v water relative to the total volume of the reaction mixture expedites the separation of the phases by interrupting the emulsifying action of ethanol with an immediate separation of glycerol from biodiesel. The characterization of the produced biodiesels was performed using hydrogen nuclear magnetic resonance (1H NMR) and gas chromatography (GC). 1H NMR indicated a 96.9% conversion of triglycerides to biodiesel. The fatty acid compositions of the synthesized ethyl and methyl biodiesels determined using GC are essentially the same.

Simple Methods via Mid-IR or 1 H NMR Spectroscopy for the Determination of the Iodine Value of Vegetable Oils

Two methods for determining the iodine value in vegetable oils are described. One employs mid-infrared (mid-IR) spectroscopy and the other uses hydrogen nuclear magnetic resonance (1H NMR). The determination of the iodine value is based on either the transmittance intensity of mid-IR signals or on the 1H NMR signal integration and multivariate calibration. Both of the methods showed adequate coefficients of determination (r2 = 0.9974 and 0.9978, respectively) when compared to Wijs method, which is recommended by the norm EN 14111. A statistical comparison between the results from the proposed methods and from Wijs method shows that both instrumental methods offer equivalent results and greater precisions compared to Wijs method. The regressions obtained from the constructed models were considered statistically significant and useful for making predictions. The proposed methods present several advantages compared to Wijs method because they significantly reduce analysis time, reagent consumption and waste generation. Furthermore, an analyst can choose between the mid-IR or 1H NMR to determine the iodine value.

Quantificação de antimônio em garrafas de politereftalato de etileno (PET) brasileiras por fluorescência de raios-X e avaliação quimiométrica para verificar a presença de pet reciclado através do teor de ferro

Antimony is a common catalyst in the synthesis of polyethylene terephthalate used for food-grade bottles manufacturing. However, antimony residues in final products are transferred to juices, soft drinks or water. The literature reports mentions of toxicity associated to antimony. In this work, a green, fast and direct method to quantify antimony, sulfur, iron and copper, in PET bottles by X-ray fluorescence spectrometry is presented. 2.4 to 11 mg Sb kg-1 were found in 20 samples analyzed. The coupling of the multielemental technique to chemometric treatment provided also the possibility to classify PET samples between bottle-grade PET/recycled PET blends by Fe content.

A Simple, Fast, and Green Titrimetric Method for the Determination of the Iodine Value of Vegetable Oils Without Wijs Solution (ICl)

A simple titrimetric method for the determination of the iodine value of vegetable oils is proposed. Water is used as the principal solvent, and ethanol is employed to dissolve the oil samples and to prepare a standard iodine solution. The determinations made by the proposed method were compared with the procedure described in the American Oil Chemists’ Society Cd-1-25 method, which is essentially the Wijs method and uses Wijs solution (ICl). Vegetable oils from 15 different sources were analyzed using the two methods, and a statistical comparison between them showed that both methods offer equivalent results and precision. As advantages, the proposed procedure is simpler, faster, greener (with significantly less toxic chemicals), and of lower cost (ten times cheaper) compared with the Wijs method.

Use of portable X-ray fluorescence to discriminate brands of nail polishes: a potential forensic tool

In forensic analysis, a small quantity of a particular material (hairs, fibers, soils, glasses, paints, among others) can be important to elucidate the sequence of events in a crime scene or to establish the relationship among subjects and facts. There are several examples of cosmetics used as forensic evidences, such as lipsticks and nail polishes. The composition of nail polishes varies according to brand, color and purpose of the product. In this work, the separation of Brazilian nail polishes according to their brand was evaluated using a portable energy dispersive X-ray fluorescence spectrometer (EDXRF) and principal component analysis (PCA). The nonsupervised classification of five brands indicates that the proposed methodology may be a quick, low cost and green alternative to discriminate brands and other characteristics related to a nail polish sample, as possible evidence in crime scenes.

Alternative method to quantify biodiesel and vegetable oil in diesel-biodiesel blends through 1H NMR spectroscopy

An alternative method is proposed for the quantitative analysis of biodiesel in diesel-biodiesel blends. It is based on hydrogen nuclear magnetic resonance (1H NMR) spectroscopy and applies univariate calibration, in which the integrals of the spectra are considered. Statistical comparisons between the results obtained from the method proposed here and from the infrared (IR) spectrometry method, which is recommended by the European Standard EN 14078, show that the 1H NMR method offers equivalent results compared with standard ones. Furthermore, the proposed 1H NMR method recognizes the difference between biodiesel and vegetable oil, whereas the IR method cannot. Therefore, the 1H NMR method developed to quantify biodiesel in diesel-biodiesel blends is proposed here as a more practical and efficient alternative to the official method, because besides quantifying biodiesel in blends, it indicates adulteration with vegetable oil, either as the intentional and illegal addition of this raw material or because of a low degree of transesterification conversion during biodiesel synthesis.

Simultaneous determination of six quality parameters of biodiesel through 1 H NMR spectroscopy and partial least squares

Biodiesel quality is checked by determining several parameters. Considering the large number of analyses in this verification, as well as the disadvantages of the use of toxic solvents and waste generation, multivariate calibration is suggested to reduce the number of tests. In this work, hydrogen nuclear magnetic resonance (1H NMR) spectra were used to build multivariate models, from partial least squares (PLS), in order to perform simultaneous determination of six important quality parameters of biodiesel: density at 20°C, kinematic viscosity at 40°C, iodine value, acid number, oxidative stability, and water content. 1H NMR spectrum reflects the structures of the compounds present in biodiesel and showed suitable correlations with the six parameters. In addition, the models were appropriate to predict all parameters for external samples. Thus, the alliance between 1H NMR spectra and PLS was shown to be applicable to extract a lot of information about biodiesel quality, significantly reducing analysis time, reagent and solvent consumption, and waste generation.