RESUMO
The production of waxes from vegetable oils, such as palm oil, for use as a base material in products for human applications is an alternative to those derived from petroleum and animals. Seven palm oil-derived waxes, called biowaxes (BW1-BW7) in this work, were obtained by catalytic hydrotreating of refined and bleached African palm oil and refined palm kernel oil. They were characterized by three properties: compositional, physicochemical (melting point, penetration value, and pH), and biological (sterility, cytotoxicity, phototoxicity, antioxidant, and irritant). Their morphologies and chemical structures were studied by SEM, FTIR, UV-Vis, and 1H NMR. The BWs presented structures and compositions similar to natural biowaxes (beeswax and carnauba). They had a high concentration of waxy esters (17%-36%) with long alkyl chains (C, 19-26) per carbonyl group, which are related to high melting points (<20-47.9 °C) and low penetration values (2.1-3.8 mm). They also proved to be sterile materials with no cytotoxic, phototoxic, antioxidant, or irritant activity. The biowaxes studied could be used in cosmetic and pharmacological products for human use.
RESUMO
Reactions as the attack by naphthenic and hydrogen sulfide have caused corrosion problems in the petroleum industry due to they affect the crude oil heating furnaces and distillation towers at temperatures between 220 and 400⯰C. The total acid number (TAN) measurement has been used as a test to quantify the acid compounds in crude oils and has shown to be a reliable indicator of their corrosion degree. However, the standard method for the TAN measurement, ASTM D-644, involves long times, environment unfriendly wastes and high costs for each analysis. A more appropriate method for the TAN determination is implemented in this paper, by correlating Fourier transform infrared spectroscopy (FTIR) spectral data of the samples with the standard method measurements using multivariate regression models. In particular, the intensities and frequencies of their mid-infrared attenuated total reflectance (MIR-ATR) spectra (4000 - 400â¯cm-1) are used as independent variables of several principal component regression (PCR) and partial least squares regression (PLSR) models. The latter are employed to correlate the spectra with their respective TAN values so as to obtain a suitable prediction model. Twenty-six (26) samples of Colombian crude oils are used for the study with a TAN ranging from 0.1 to 6.8â¯mg KOH/g crude oil (ASTM D-664). The models are evaluated according to the coefficient of determination (R2), the root mean square error of calibration (RMSEC) and of prediction (RMSEP). The best model is obtained via PLSR using as few as four components (i.e. factors), which attains a calibration R2 of 0.981 and an RMSEC of 0.317â¯mg KOH/g crude oil, while for prediction it attains an R2 of 0.996 and an RMSEP of 0.160â¯mg KOH/g crude oil. It is observed that the functional groups COOH, CH3 and CH2 contribute the most to the prediction models. The designed methodology is faster and environmentally friendly since it does not require sample pretreatment and the use of toxic reagents, and of low-cost compared with the standard procedure since FTIR measurements can be easily taken anywhere using a hand-held or portable spectrometer and a laptop.