In this work, a method was developed for the quantification of total glycerol in biodiesel using solid phase extraction (SPE) coupled with enzymatic-spectrophotometric determination.
An experimental procedure is presented that was developed by fifth-year
chemical engineering and industrial chemistry undergraduates at the
Federal University of Rio de Janeiro doing the discipline on Experimental
Organic Technology. The aim of this study was to apply the solvatochromic
effect of the dye Nile Blue chloride to the characterization of biodiesel/diesel
blends with different biodiesel content, using an alternative image
processing analysis method involving low-cost, simple, and rapid assays.
The effect of the solvatochromic dye Nile Blue chloride was monitored
using the software ImageJ, which is being used currently, yielding
rapid and effective responses. As an outcome, the students proposed
a procedure that had potential application to colorimetric determination
of biodiesel content in diesel oil. This gave students the opportunity
to put the knowledge acquired in the course into practice, by dealing
with issues concerning the fuels industry, making the learning process
more dynamic, engaging, and effective.
Biodiesel
content on biodiesel/diesel blends is obtained by determining
the band intensity of CO bond in the fatty acid methyl esters
(FAME) of the biodiesel by mid-infrared spectroscopy (reference method:
EN 14078, 2014). The potential for biodiesel/diesel blends to be adulterated
with vegetable oils constitutes a limitation of the reference method’s
capacity to accurately quantify the biodiesel content in these blends
since vegetable oils, composed primarily of triacylglycerols, also
contain the CO bond. This study employed normal-phase high-performance
liquid chromatography with a refractive index detector (NP-HPLC-RI)
to quantify the biodiesel in biodiesel/diesel blends and detect potential
adulterations of these blends with vegetable oils. Two calibration
curves (4 to 12% vol and 5 to 30% vol) were plotted for the biodiesel
quantification based on which 12 verification samples were analyzed
(samples prepared at different concentrations from the calibration
curves), as well as 20 samples of commercial diesel, acquired at gas
stations in the southeast region of Brazil. The NP-HPLC-RI method
presented good analytical performance in terms of linearity, limit
of detection (LOD), limit of quantification (LOQ), precision (repeatability),
accuracy (recovery), and robustness. Linearity was determined by the
coefficient of determination (R
2) for
concentrations of biodiesel and vegetable oil in diesel varying from
4 to 12% vol (R
2 = 0.9924 and R
2 = 0.9950, respectively) and from 5 to 30%
vol (R
2 = 0.9968 and R
2 = 0.9962, respectively). The LOD and LOQ for the quantification
of the biodiesel were 0.08 and 0.23% vol, while for the quantification
of soybean oil, these values were 0.07 and 0.21% vol, respectively.
The recovery values varied from 97.7 ± 1.8% to 107.1 ± 4.1%,
indicating good accuracy, and the method proved robust when the temperature
was changed from 40 to 35 °C. The paired sample t-test showed the nonexistence of significant differences between
the proposed and reference methods (with 95% confidence), indicating
the capacity of NP-HPLC-RI to detect and quantify biodiesel and vegetable
oil adulterants in samples of diesel both rapidly and effectively,
thereby demonstrating its importance for the quality control of this
fuel since the current methodology (EN 14078) used in several European
Union countries, as well as in Brazil and Argentina, cannot identify
this kind of adulteration and cannot accurately analyze the biodiesel
content in biodiesel/petrodiesel blends.
We present a strategy for intensified biodiesel production in a novel metallic microdevice. Additive manufacturing using Selective Laser Melting (SLM) was employed to build the metallic device consisting of multiple micro reactors monolithically integrated with multiple micro heat exchangers. This device allows high conversion rate of biodiesel production with concomitant use of the rejected heat from external source to enhance the reaction temperature and, thereby, its output. The biodiesel production was carried out using soybean oil, ethanol and NaOH as the catalyst. The influences of the reaction temperature and the residence time in the biodiesel production was examined. Biodiesel yield increased with the reaction temperature and a rate of conversion of 99.6% was achieved with a reactor residence time of less than 35 seconds. The work opens up a pathway to exploit waste heat to intensify biodiesel production and contribute significantly to global sustainability.
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