A new flow UV–Vis kinetics spectrophotometric method based on a photodegradative reaction for determining the oxidative stability of biodiesel

1H NMR and UV-Vis as Analytical Techniques to Evaluate Biodiesel Conversion and Oxidative Stability

“…The monitoring of the oxidative stability of biodiesel samples was carried out in a bench-top accelerated oxidation system (see Figure 3) associated with a UV-Vis spectrophotometer through the inspection of the increasing of the absorbance maxima at 270 nm, which corresponds to the n → π* transition, where an electron from a non-bonding orbital localized near the oxygen atom is excited to an antibonding orbital around the chromophore carbonyl (C=O), characteristic of secondary oxidation products such as α-diketones or unsaturated ketones [43,44]. Figure 7 shows that the increasing absorbance at around 270 nm corresponds to the formation of oxidation products resulting from the degradation of safflower biodiesel [33,36]. Additionally, some trends of the accelerated oxidation process can be observed, such as until 6 h, safflower biodiesel kept its average absorbance around 0.55, representing a difference of 2.83% compared to the biodiesel fresh (0 h); see Figure 8.…”

“…As an alternative to the Rancimat ® method, a bench-top accelerated oxidation system associated with UV-Vis spectroscopy to monitor maxima absorbance at 270 nm was used [33,34]. In previous works, researchers have proposed alternative methods to determine the oxidative stability (OS) of biodiesel by changing how accelerated oxidation is induced or determined.…”

“…In previous works, researchers have proposed alternative methods to determine the oxidative stability (OS) of biodiesel by changing how accelerated oxidation is induced or determined. A new approach to determine the oxidative stability (OS) of biodiesel samples produced from sunflower, grapeseed, corn, and soybean oils was published by Orozco et al [33]. This approach involves a photodegradative reaction and a flow UV-Vis kinetics spectrophotometric method.…”

Modelling and Optimization of Processing Factors of Pumpkin Seeds Oil Extraction under Uniaxial Loading

“…A UV-VIS spectrophotometer (VIS V-10 Plus, Giorgio Bormac S.r.l., Carpi, Italy) was used to describe the absorbance and transmittance of the oil samples (control and heated) at different wavelengths. This was to measure the incident light absorbed and light transmitted through the oil samples, which can be used for UV radiation problems on human health [49,50].…”

Kinetic Modeling of the Effect of Antioxidant Additives on Biodiesel Oxidation Stability

“…Various methodologies have been used to evaluate this process and verify its effects, for instance, promoting accelerated aging of biofuel samples in conditions not too different from room temperature, like through the ASTM D4625 test method, or in more severe conditions under 110 °C. , Stability monitoring could be conducted by insoluble material detection, – measurement of different properties like induction period, , viscosity, or spectroscopical ones. , Properties variations with time were considered to obtain kinetic and thermodynamical information on the oxidation process, rate of reaction, activation energy, enthalpy, and entropy, mainly in the presence of antioxidants, to check the effectiveness of the substances. , Those studies were carried out through the test method time frame of hours under high temperature, which could be complemented in due course with controlled and standardized aging procedures through weeks under temperatures more similar to room conditions (ASTM D4625).…”