No abstract

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.

No abstract

No abstract

Rhamnolipids (RLs) produced by the opportunistic human pathogen Pseudomonas aeruginosa are considered as potential candidates for the next generation of surfactants. Large-scale production of RLs depends on progress in strain engineering, medium design, operating strategies, and purification procedures. In this work, the rhlAB genes extracted from a mono_RLs_producing strain of P. aeruginosa (ATCC 9027) were introduced to an appropriate safety host Pseudomonas putida KT2440. The capability of the recombinant strain was evaluated in various media. As a prerequisite for optimal medium design, a set of 32 experiments was performed in two steps for screening a number of macro-nutritional compounds. In the experiments, a two-level fractional factorial design resolution IV was followed by a two-level full factorial one. By means of this approach, it was observed that glycerol, yeast extract, and peptone have significant positive influence on recombinant RLs production while the yeast extract/peptone two-factor and glycerol/yeast extract/peptone three-factor interactions have considerable negative effects. A wide range of variation from 0 to 570 mg/l was obtained for RLs production during the screening experiments indicating the importance of medium optimization. The results point out the opportunity for possible higher yields of RLs through further screening, mixture/combined mixture designs, and high-cell-density cultivations.