During biodiesel production, the product is contaminated with impurities such as some non‐reacted alcohol, glycerol, and catalyst. In order to comply with product requirements, these impurities must be removed, for example, by washing with water. Knowledge of the extent of water solubility in biodiesel is required to design the drying system and determine fuel quality. In the present work, the solubilities of water in biodiesels produced from sunflower and canola oils were measured within the temperature range of 24–60 °C. The solubility of water increased with increasing temperature and biodiesel unsaturation. The liquid–liquid equilibria of ternary systems of glycerol, methanol, and the above‐mentioned biodiesels were investigated experimentally at 20, 30, and 40 °C. The binodal curves were determined by using the cloud point titration method and the tie lines were measured by evaporating the methanol. Both binary and ternary data were modeled using the UNIQUAC model. The model showed good agreement with the data. Othmer‐Tobias correlations were applied and the corresponding constants were obtained. The results validated the consistency of the tie‐line data obtained experimentally.

Liquid−liquid phase equilibria of two systems of concern in the biodiesel production process are determined experimentally. The first system is the binary mixture of water + biodiesel within a temperature range of 297.2 to 333.2 K, in order to determine water solubilities in two biodiesels prepared from palm and soya oil. The experimental results showed that water solubilities were limited to values below 0.05 mol % and that the solubility increased with increasing temperature and biodiesel unsaturation. Next, the phase diagrams of ternary mixtures of glycerol + methanol + mentioned biodiesels were determined at three temperatures (293.2, 303.2, and 313.2 K). The reliability of the experimental data of tie lines was ascertained using the Othmer-Tobias relation. The UNIQUAC model was then used to model both the binary and ternary experimental data. Results showed the suitability of this model in correlating the phase behavior of such systems. ■ INTRODUCTIONThe production of alternative fuels from renewable sources is becoming attractive because of the high prices of fossil fuels, the decline of fuel reserves, and the concern about the environment. 1 Nowadays, biodiesel is receiving increasing attention as a renewable fuel, because of particular advantages over petrodiesel: In contrast to diesel fuel, biodiesel contains longchain alkyl esters with oxygen in their structures, which results in more complete burning. In addition, it has a higher flash point compared to petrodiesel. Therefore, this fuel is less flammable and more safe. In addition, its cetane number is higher than that of petrodiesel because the fatty acid methyl esters used as biodiesels contain long-chain compounds similar to long-chain alkanes such as hexadecane, which make for a higher-quality diesel. 2 There are four basic methods for biodiesel production from oils and fats: base-catalyzed transesterification, direct acidcatalyzed transesterification, conversion of the oil into its fatty acids and then into biodiesel, and noncatalytic transesterification of oils and fats such as the BIOX process or the supercritical alcohol process. 3 In the base-catalyzed transesterification method, biodiesel is obtained via a transesterification reaction of triglycerides from oils and fats with an excess of alcohol, and using a catalyst to accelerate the reaction. The reaction product is composed of fatty acid methyl esters and glycerol as a byproduct. After biodiesel production, some steps are carried out for the separation and purification of the desired product. This includes respectively, the separation of the biodiesel phase from the glycerol phase, recycling the unreacted alcohol, water-washing, and drying.Therefore, accurate information on the phase equilibria of the components involved in biodiesel production, and the ability to predict equilibria where information is not available, is necessary in order to determine optimum operating conditions for the separation and purification units of biodiesel production. Some studies have been carried out in this ...

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Introduction: Bacterial infections have always been a major threat to public health and humans' life, and fast detection of bacteria in various samples is significant to provide early and effective treatments. Cell-culture protocols, as well-established methods, involve labor-intensive and complicated preparation steps. For overcoming this drawback, electrochemical methods may provide promising alternative tools for fast and reliable detection of bacterial infections. Methods: Therefore, this review study was done to present an overview of different electrochemical strategy based on recognition elements for detection of bacteria in the studies published during 2015-2020. For this purpose, many references in the field were reviewed, and the review covered several issues, including (a) enzymes, (b) receptors, (c) antimicrobial peptides, (d) lectins, (e) redox-active metabolites, (f) aptamer, (g) bacteriophage, (h) antibody, and (i) molecularly imprinted polymers. Results: Different analytical methods have developed are used to bacteria detection. However, most of these methods are highly time, and cost consuming, requiring trained personnel to perform the analysis. Among of these methods, electrochemical based methods are well accepted powerful tools for the detection of various analytes due to the inherent properties. Electrochemical sensors with different recognition elements can be used to design diagnostic system for bacterial infections. Recent studies have shown that electrochemical assay can provide promising reliable method for detection of bacteria. Conclusion: In general, the field of bacterial detection by electrochemical sensors is continuously growing. It is believed that this field will focus on portable devices for detection of bacteria based on electrochemical methods. Development of these devices requires close collaboration of various disciplines, such as biology, electrochemistry, and biomaterial engineering.