Optimization of process variables for essential oil components from Satureja hortensis by supercritical fluid extraction using Box-Behnken experimental design

The oil and extracts of Satureja hortensis cultivated in Iran were extracted using supercritical carbon dioxide and hydrodistillation method. The oil and extracts were analyzed by GC-FID and GC/MS. The compounds were identified according to their retention indices and mass spectra (EI, 70 eV). The effects of various parameters such as pressure, temperature, percent of modifier (methanol) and extraction time, were investigated by a fractional factorial design (2^4-1) to determine the significant parameters and their interactions. The results showed that the pressure, temperature and percent of modifier are significant (p < 0.05), but the extraction time was found to be insignificant. The response surface methodology (RSM), based on Box-Behnken design was employed to obtain the optimum conditions of the significant parameters (pressure, temperature and percent of modifier). The optimal conditions could be obtained at a pressure of 35.0 MPa, temperature of 72.6 °C, and 8.6% (v/v) for methanol. The main extracted components using SFE were γ-Terpinene (35.5%), Thymol (18.2%) and Carvacrol (29.7%).     

Oxidative desulfurization of synthetic diesel using supported catalysts: Part II. Effect of oxidant and nitrogen-compounds on extraction–oxidation process

Oxidative desulfurization (ODS) of a synthetic diesel was carried out at mild conditions (atmospheric pressure and 60 °C) in presence of V₂O₅/Al₂O₃ and V₂O₅/TiO₂ catalysts. Two main aspects were studied: the effect of the oxidant reagent and the presence of nitrogen compounds on ODS of benzothiophenic compounds prevailing in diesel, such as benzothiophene, dibenzothiophene and alkyl substituted in positions 4 and 6. Results show that activity is improved when using hydrogen peroxide, as oxidant reagent, and V₂O₅/Al₂O₃, as catalyst. This result was attributed to the high decomposition of peroxide due to the presence of catalyst. In presence of nitrogen compounds, the ODS activity decreases in the order: quinoline > indole > carbazole. In order to explain this effect, successive chemisorption of DBT and quinoline on V₂O₅/Al₂O₃ catalyst was evaluated by FT-IR, and the results show that DBT is displaced by quinoline, occupying the adsorption sites of catalyst. N-compound effect could be explained by strong adsorption of nitrogen compounds on catalytic sites.     

Optimization of microwave-assisted extraction for picroside I and picroside II from Picrorrhiza kurroa using Box-Behnken experimental design

The response surface methodology was employed to study the optimization of microwave-assisted extraction of picroside I and picroside II from Picrorrhiza kurroa Royle rhizomes. The effects of solid to solvent ratio, and extraction temperature, time and solvent on the yields of picroside I and picroside II have been investigated using Box-Behnken experimental design. The experimental data were fitted to second-order polynomial equations using multiple regression analysis and analyzed using the appropriate statistical method. By solving the regression equation and analyzing 3-D plots, the optimum extraction conditions were found to be: solid to solvent ratio, 10 : 90 (w/v); temperature, 60 °C; and extraction time, 60 s. Under the optimal conditions, the yields of picroside I and picroside II are 41.23 and 6.12 mg·g^–1 feed respectively, which are in good agreement with the predicted values. The ratio of solid to solvent significantly affects the yields of picroside I and picroside II. Application of microwave-assisted extraction of picroside I and picroside II from P. kurroa would dramatically reduce extraction time and solvent consumption.     

Optimization of Xylanase Production from Penicillium sp.WX-Z1 by a Two-Step Statistical Strategy: Plackett-Burman and Box-Behnken Experimental Design

The objective of the study was to optimize the nutrition sources in a culture medium for the production of xylanase from Penicillium sp.WX-Z1 using Plackett-Burman design and Box-Behnken design. The Plackett-Burman multifactorial design was first employed to screen the important nutrient sources in the medium for xylanase production by Penicillium sp.WX-Z1 and subsequent use of the response surface methodology (RSM) was further optimized for xylanase production by Box-Behnken design. The important nutrient sources in the culture medium, identified by the initial screening method of Placket-Burman, were wheat bran, yeast extract, NaNO(3), MgSO(4), and CaCl(2). The optimal amounts (in g/L) for maximum production of xylanase were: wheat bran, 32.8; yeast extract, 1.02; NaNO(3), 12.71; MgSO(4), 0.96; and CaCl(2), 1.04. Using this statistical experimental design, the xylanase production under optimal condition reached 46.50 U/mL and an increase in xylanase activity of 1.34-fold was obtained compared with the original medium for fermentation carried out in a 30-L bioreactor.     

Effect of water on extractive desulfurization of fuel oils using ionic liquids:A COSMO-RS and experimental study

When evaluating ionic liquids(ILs) for extractive desulfurization(EDS) of fuel oils, the inevitable presence of water in the system may have a significant and in many cases strongly negative effect. However, few studies have considered this particular issue and a promoted water effect on EDS is scarcely reported. In this work,COSMO-RS was firstly employed to calculate the capacity and selectivity for EDS of various IL/H_2 O mixtures,which cover different IL characters and a wide water concentration range. Experiments were then conducted with a representative IL [C_4MIM][H_2PO_4], whose stable and even promoted extraction performance with a small amount of water was suggested by COSMO-RS. Through analyses of the desulfurization ratio, the crosssolubility and the water content in the desulfurized fuel, the promoted effect of water within a certain range(b 10 wt%) was experimentally demonstrated. Moreover, such effect of water was explained combining the viscosity, the solvent–solute interactions and the COSMO-RS based analysis.     

Process optimisation using the combination of simulation and experimental design approach: Application to wet air oxidation

This study develops a coupling of energetic and experimental design approaches on a given configuration of wet air oxidation process (WAO), applied for wastewater containing a hard chemical oxygen demand (phenol for instance). Taking into account thermodynamic principles and process simulation, the calculation of minimum heat required by the process, exergetic efficiency and work balance is presented. Five parameters are considered: pressure (20-30 MPa); temperature (200-300 °C); chemical oxygen demand (23-143 g l⁻¹); air ratio (1.2-2) and temperature of exiting steam utilities (160-200 °C). Using the surface response method, it appears that initial chemical oxygen demand and temperature are the two parameters that mainly influence the result. With the modelling, good conditions for the functioning of the presented process are the following: pressure of 19.4 MPa, temperature of 283 °C, chemical oxygen demand of 54.9 g l⁻¹, air ratio of 1.7 and vapour temperature of 183 °C.     

On the costs of parameter uncertainties. Part 2: Impact of EVOP procedures on the optimization and design of experiments

Pinto (1998) showed that an economical value might be assigned to model parameter uncertainties, which could be used for process optimization and for taking decisions during sequential experimental designs. The procedure is extended to take into account the fact that plant operation conditions change with time, leading to improvements of the plant operation and allowing the partial recovering of losses introduced by uncertain parameters during plant design. It is shown that the use of EVOP (Evolutionary Operation Procedures) during plant operation may reduce the cost of parameter uncertainties, exerting a major impact on process optimization and optimal design of experiments.     

Electropolishing of 304 stainless steel: Surface roughness control using experimental design strategies and a summarized electropolishing model

The electropolishing (EP) settings for obtaining 304 stainless steel (304SS) with variable surface roughness factors (Ra) in a mixture containing phosphoric acid, sulfuric acid, and glycerol were achieved using experimental design strategies, including the fractional factorial design (FFD) coupled with the response surface methodology (RSM) and the path of the steepest ascent. The bath temperature and polishing time were found to be the strongest factors affecting Ra of 304SS in the FFD study. The glycerol content and polishing current density involved strong interactions with the bath temperature although both factors only showed marginal significant effects. The effects of bath temperature and polishing time on Ra of 304SS were examined in the study of the steepest ascent path for controlling the surface roughness. The results showed that Ra of 304SS is decreased with decreasing the bath temperature and polishing time but increased when the temperature was lower than 20 °C. A summarized model with a new idea on the molecular interactions in the polishing bath is proposed to elucidate the phenomena found in this work. The morphologies and Ra of 304SS electropolished under various conditions were examined by means of the SEM photographs and AFM analyses.     

Study of the influence of reaction conditions on the degree of substitution,intrinsic viscosity,and yield of oxidized cellulose acetate by factorial experimental design

A half‐fraction, two‐level, four‐factor factorial experimental design was used to study the effects of the acetic anhydride concentration, reaction temperature, reaction time, and sulfuric acid concentration on the degree of substitution, intrinsic viscosity, and yield of oxidized cellulose acetate (OCA). Oxidized cellulose containing 20% (w/w) carboxylic acid was used as the starting material. The data were fitted by multiple regression analysis with SAS software. The correlation coefficients obtained from plots of the predicted and observed values for the degree of substitution, intrinsic viscosity, and yield were 0.985, 0.993, and 0.991, respectively. Residual normal plots of the regression models showed a linear relationship. Lenth and main‐factor‐effect plots revealed an increase in the degree of substitution of OCA with an increasing concentration of acetic anhydride. The latter had no effect on the intrinsic viscosity and yield of OCA. An increase in the reaction temperature led to an increase in the degree of substitution and a decrease in the intrinsic viscosity and yield of OCA. The influence of the reaction time on the degree of substitution and intrinsic viscosity followed a trend similar to that observed with the reaction temperature, but the yield of OCA was unaffected. Increasing the concentration of sulfuric acid reduced the degree of substitution, intrinsic viscosity, and yield of OCA. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 696–705, 2005     

Adsorption of basic red 9 on activated waste Gossypium hirsutum seeds: Process modeling,analysis and optimization using statistical design

Sulfuric acid activated immature Gossypium hirsutum seed was utilized as adsorbent for the batch adsorption of basic red 9. The main and interactive effects of five process factors like, adsorbent dose, initial dye concentration, contact time, pH and temperature were investigated to select the influencing key factors via 2⁵ two-level full factorial design. Box–Behnken statistical design with the selected key factors employed for process optimization. The simultaneous optimization by Derringer's desirability function indicated that 54.27% removal of BR9 could be possible at the optimal conditions. Isotherm and kinetic studies confirmed the chemisorption on homogeneous and heterogeneous patches.