No abstract

Ultrasound has been used to intensify the extraction of phenolic compounds from many agro-food products. However, there is still a lack of understanding on how the ultrasonic energy is influenced by blends of different solvents and how this impacts the extraction process. This work studied the effect of ethanol, acetone and hexane blends on the ultrasonic energy generated during the extraction of phenolic compounds from Mango peel, using an ultrasonic-assisted extraction (UAE) and a conventional solvent extraction (CSE).A simplex centroid mixture design and a special cubic regression model were used to evaluate the total phenolic compounds (TPC), antioxidant activity (AA) and ultrasonic intensity (UI) as a function of the solvents proportions. The greatest TPC was obtained with the ethanol-acetone blend (60-40%) for CSE (205.08 mg GAE/100 g DM) and UAE (1493.01 mg GAE/100 g DM). Likewise, an increase (avg. 630%) was observed in TPC when the ultrasound was applied for all solvents and their blends. The TPC showed a good correlation (R 2 =0.81) with the UD, with higher UD resulting in larger amounts of TPC extracted.Nevertheless, for the ethanol-acetone blend there was a decrease of 14.2% of the AA for the UAE, which could be due to the sonochemical reactions taking place at the high UD achieved for that blend. The results of this work indicate that the solvent composition and use of ultrasound should be carefully selected to achieve the desired extraction objectives.

No abstract

This contribution evaluates systematic but rigorous methodologies to characterize kinetics and heat transfer mechanisms and states statistical and phenomenological criteria to model an industrial‐scale wall‐cooled packed‐bed reactor for the oxidative dehydrogenation of ethane over a MoVTeNbO catalyst. A set of kinetic formalisms was submitted to regression analyses with the reparametrized form of the Arrhenius and van't Hoff equations. Heat transfer parameters (HTP) were determined by evaluating either the effect of hydrodynamics or the type of temperature measurements on reactor simulations. Eley–Rideal formalism led to the most proper approach to describe kinetics, presenting thermodynamic consistency and statistical confidence; whereas the HTP determined out of radial and axial measurements and accounting for hydrodynamics led to the determination of the most reliable transport parameters presenting phenomenological and statistical significance. These results stated criteria to model with confidence the performance of the studied technology, paving the way for its further rigorous design, optimization, or intensification.

No abstract