Search

The aim of the study to optimize the operating parameters on the yield, composition, time and kinetics in extraction of essential oils from different Lavandula angustifolia flowers by microwave assisted steam distillation (MSD) in comparison to conventional steam distillation (SD). A preliminary study allowed for the determination of the most influential operating factors, namely water vapor flow rate and microwave heating power. The yield obtained by MSD was comparable to that obtained by SD, while the extraction time was considerably reduced with 6 min for MSD compared to 30 min for SD. Optimization of the operating parameters was assessed using response surface methodology (RSM). The optimal treatment conditions obtained were: 8 g·min–1 for the steam flow rate, 500 W for the microwave power and 6 min for the extraction time. The main compounds identified in the different lavender essential oils extracted by MSD chosen as the variables in a multivariate study. A composite centered design based on a response surface methodology was investigated for each major constituent found in the oils. The results showed that the chemical composition of the lavender essential oil was strongly influenced by the MSD operating conditions. The choice of particular operating parameters will allow for extraction of a specific compound. [ABSTRACT FROM AUTHOR]

The objective of this experimental work was to synthesize biofuels from used food oils by a transesterification chemical process. The influence of the parameters affecting the yield of the transesterification reaction were assessed and consequently optimized to obtain good quality biodiesel, with an optimal conversion. Their chemical composition and calorific value make biofuels good alternatives to fossil fuels. To make them compatible with engines, some transformations are required to decrease their viscosity and improve their properties. The processes and their parameters were optimized by experimental methods and the produced fuels were characterized with respect to European Norms (EN 14214). The results of the investigation showed that the best yield is obtained using a mass of CaO = 0.895 g, a temperature = 40°C and a reaction time = 68.85 h. [ABSTRACT FROM AUTHOR]

The main objective of this study was to demonstrate the efficiency and to optimize the operating conditions of photodegradation of paracetamol in the presence of suspended titanium dioxide catalyst in a photoreactor. An experimental design study was carried out using central composite design modelling. Optimization was applied to the tubular reactor under fixed photonic flux with radiation from two 24-watt UV-A lamps. The optimal values of the operating parameters were found to be pH of 7.288, TiO2 concentration of 0.9932 g·L-1 and paracetamol initial concentration of 15 mg·L-1. The paracetamol degradation rate approached 98.46% under optimal conditions. Modelling of the system led to a second-degree polynomial. Regression analysis gave an R² value of 0.977 which meant good agreement between the experimental results and the predicted values. An interaction was demonstrated between the catalyst and the operating parameters (pH, CPara and CTiO2) as well as between the model pollutant concentration and the pH had an insignificant effect on the yield compared to that of the quantity of the catalyst and the initial pollutant concentration. [ABSTRACT FROM AUTHOR]