Three-level Box-Behnken Experimental Design Research Articles

Optimization of subcritical fluid extraction of seed oil from Nitraria tangutorum using response surface methodology

Subcritical fluid extraction (SFE) technology was used to extract oil from Nitraria tangutorum seed. The best possible combination of extraction parameters was found using response surface methodology (RSM) in a three-variable, three-level Box-Behnken experimental design (BBD). The optimum extraction parameters were an extraction time of 40 min, an extraction pressure of 0.60 MPa, an extraction temperature of 44 °C and a raw material particle size of 0.45 mm. Conventional solvent extraction and supercritical CO2 fluid extraction were comparatively used. The yield of seed oil obtained using SFE was 12.92%, which was similar to or higher than the other methods. The chemical compositions of the seed oil, determined by GC–MS, indicate that its unsaturated fatty acids content was 97%. SFE proved to be an effective technique for extracting oil from N. tangutorum.

Optimization of Extraction of Bioactive Material-Polysaccharides from the Roots of <i>Taraxacum mongolicum</i> by Box-Behnken Experimental Design

Dandelion (Taraxacum spp) is an medical active materials used in many traditional and modern herbal medical systems, its polysaccharides have many bioactivities. Taraxacum mongolicum is one of the most widely consumed as Chinese herbal medicine and root tea in Changbai Mountains area, Northeast China. In this study, a procedure for the extraction of polysaccharides from the root of T mongolicum(TMRPS) was established. Based on single-variable tests experiment to determine the ranges of the extraction parameters (extraction temperature (X1), extraction time (X2), and ratio of solvent to raw material (X3)), response surface methodology (RSM) was used to optimize for these extraction parameters (X1, X2, X3) enhancing the forward extraction efficiency of TMRPS by a three-level three-variable Box-Behnken experimental design. The results showed that the ranges of the extraction parameters were determined as 60°C-80°C(X1),1h-3h (X2),20-40(v/m)(X3) by single-variable tests and the maximal yield (9.01%) of TMRPS was reached at extraction temperature 70.2°C, extraction time 1.79 h and ratio of solvent to raw material 28.0 (v):1 (m). Convenient for experiment, appropriate readjustment of these extraction parameters was made. Under these readjusted conditions, the mean extraction yield of TMRPS was 8.85%, which was near to theoretical calculation and indicates that these results were agree closely with model predictions.

Ionic liquid-salt aqueous two-phase extraction based on salting-out coupled with high-performance liquid chromatography for the determination of sulfonamides in water and food

Ionic liquid-salt aqueous two-phase extraction coupled with high-performance liquid chromatography with ultraviolet detection was developed for the determination of sulfonamides in water and food samples. In the procedure, the analytes were extracted from the aqueous samples into the ionic liquid top phase in one step. Three sulfonamides, sulfamerazine, sulfamethoxazole, and sulfamethizole were selected here as model compounds for developing and evaluating the method. The effects of various experimental parameters in extraction step were studied using two optimization methods, one variable at a time and Box-Behnken design. The results showed that the amount of sulfonamides did not have effect on the extraction efficiency. Therefore, a three-level Box-Behnken experimental design with three factors, which combined the response surface modeling, was used to optimize sulfonamides extraction. Under the most favorable extraction parameters, the detection limits (S/N = 3) and quantification limits (S/N = 10) of the proposed method for the target compounds were achieved within the range of 0.15-0.3 ng/mL and 0.5-1.0 ng/mL from spiked samples, respectively, which are lower than or comparable with other reported approaches applied to the determination of the same compounds. Finally, the proposed method was successfully applied to the determination of sulfonamide compounds in different water and food samples and satisfactory recoveries of spiked target compounds in real samples were obtained.

Response Surface Modeling of Ultrasound-Assisted Dispersive Liquid–Liquid Microextraction for Determination of Benzene, Toluene and Xylenes in Water Samples: Box–Behnken Design

A simple, fast and effective pre-concentration procedure for the extraction of benzene, toluene and xylenes isomers (BTX) was developed using an ultrasound-assisted dispersive liquid-liquid microextraction coupled with gas chromatography-flame ionization detector in water samples. The effects of different experimental parameters in the extraction step including type and volume of extraction and dispersive solvents, ionic strength, extraction time and sample volume were studied using two techniques, namely one-variable-at-a-time and response surface methodology. The results of "one-variable-at-a-time" showed that the ionic strength and extraction time were not significant on the extraction efficiency. Therefore, a three-factor, three-level Box-Behnken experimental design was employed to optimize the BTX extraction. The optimal conditions were determined to be a volume of extraction solvent (chloroform) of 51μL, volume of dispersive solvent (methanol) of 514μL and volume of sample of 12mL. The enrichment factors of 241.2-305.1, the limit of detections of 205-382ngL(-1) were obtained for the BTX at the optimum conditions. In addition, the relative standard deviations for 50μgL(-1) of the BTX in the water samples were found to be in the range of 1.9%-5.7% (n=5). The developed procedure was then applied for the extraction and determination of BTX in the water samples.

Response surface modelling of lead pre-concentration from food samples by miniaturised homogenous liquid–liquid solvent extraction: Box–Behnken design

In this study, a new method called miniaturised homogenous liquid–liquid extraction, followed by graphite furnace atomic absorption spectrometry, was developed for the extraction and determination of lead from food samples. The procedure was based on the fast extraction of lead from an acetic acid sample solution into 0.5mL chloroform, as an extraction solvent. After adding water into the mixture, the extracting solvent phase immediately formed a distinct water-immiscible phase below the vial, which could easily be separated, evaporated and re-dissolved in 1.0mL nitric acid 0.1molL−1 for further analysis. The effects of various experimental parameters in extraction step were studied using two optimisation methods, one variable at a time and Box–Behnken design. The results showed that the amount of salt and extraction time did not have effect on the extraction efficiency. Therefore, a three-level Box–Behnken experimental design with three factors, which combined the response surface modelling, was used to optimise lead extraction. Three independent variables, including pH of solution (ranging from 6.5 to 10.5), concentration of dithizone as chelating agent (ranging from 0.05 to 0.5μgL−1) and extracting solvent volume (ranging from 300 to 900μL) were respectively coded as pH, D and V at three different levels (−1, 0 and 1). In this study, the optimum condition was determined at pH 8.4, a volume of chloroform at 0.45mL, and concentration of dithizone at 0.5μgL−1. Under the optimum condition, the limit of detection (LOD) was 0.05μgL−1. Furthermore, the relative standard deviation of the ten replicate was <5.0%. The developed procedure was applied to the extraction and determination of lead in the food samples.

Treatment of simulated industrial wastewater by photo-Fenton process. Part I: The optimization of process parameters using design of experiments (DOE)

The study reported the application of the photo-Fenton process for the treatment of simulated industrial wastewater upon pretreatment by the dark-Fenton process. The process efficiency which depends on several important process parameters such as initial pH, iron catalyst and oxidant concentration, and the UV irradiation type, was investigated. To consider the combined effects of studied process parameters, three-factor three-level Box–Behnken experimental design combined with response surface modeling was applied. The quadratic models predicting the mineralization of simulated industrial wastewater by the applied photo-Fenton processes were developed. ANOVA was applied to evaluate the significance of models and models’ components. The obtained results indicated that both models can be characterized as highly accurate and predictive for the mineralization of simulated industrial wastewater. Our results show that both photo-Fenton processes can be successfully applied for the treatment of the studied simulated industrial wastewater. The presence of oxalates in simulated industrial wastewater strongly influenced the conditions for the maximal efficiency of applied photo-Fenton processes regarding the type of UV irradiation. The optimal conditions were determined to be: initial pH 3.88, [Fe 2+] = 5.01 mM (along with [Fe 3+] = 8.0 mM) and [H 2O 2] = 30 mM in the case of photo-Fenton process operated with UV-C irradiation; and pH 1.9, [Fe 2+] = 8.39 mM (along with [Fe 3+] = 8.0 mM) and [H 2O 2] = 30 mM in the case of UV-A light application. The “pseudo”-second order mineralization kinetic of simulated industrial wastewater was determined in both cases with the calculated rate constants at determined optimal conditions: k1 obs = 12.94 × 10 −2 M −1 s −1 and k2 obs = 9.71 × 10 −2 M −1 s −1 for UV-C/Fe/H 2O 2 and UV-A/Fe/H 2O 2 processes, respectively.

Degradation of chlorinated hydrocarbons by UV/H2O2: The application of experimental design and kinetic modeling approach

The aim of the study was to develop a detail mathematical model describing the degradation of chlorinated hydrocarbon pollutants in water by UV/H2O2 process. As a model representative of chlorinated hydrocarbons para-chlorophenol (p-CP) was chosen. A degradation mechanism of parent pollutant to its aromatic and aliphatic by-products, as well as the mineralization of simulated wastewater, was included in the model. The optimal values of operating parameters of UV/H2O2 process influencing the treatment efficiency were established by the means of the two-factor three-level Box–Behnken experimental design combining with response surface modeling (RSM) and quadratic programming. The results of such experimental design using different statistical tools showed that pH 6.8 and pollutant/oxidant ratio 1:199 maximize the performance of oxidative treatment system. The model was tested to evaluate accuracy in predicting system behavior at different process conditions and pollutant concentrations. Rather high accuracy of developed model was demonstrated at all tested conditions. Good accordance of the data predicted by model and the empirically obtained data was confirmed by calculated standard deviation (SD) for each experimentally monitored parameter. Hence, the developed mathematical model describing the kinetic of p-CP degradation by UV/H2O2 can be characterized as interpretable, transparent and accurate, and therefore can be used as a tool for maximizing efficiency of wastewater treatment process.

Response surface modeling of Pb(II) removal from aqueous solution by Pistacia vera L.: Box–Behnken experimental design

A three factor, three-level Box–Behnken experimental design combining with response surface modeling (RSM) and quadratic programming (QP) was employed for maximizing Pb(II) removal from aqueous solution by Antep pistachio ( Pistacia vera L.) shells based on 17 different experimental data obtained in a lab-scale batch study. Three independent variables (initial pH of solution (pH 0) ranging from 2.0 to 5.5, initial concentration of Pb(II) ions ( C 0) ranging from 5 to 50 ppm, and contact time ( t C) ranging from 5 to 120 min) were consecutively coded as x 1, x 2 and x 3 at three levels (−1, 0 and 1), and a second-order polynomial regression equation was then derived to predict responses. The significance of independent variables and their interactions were tested by means of the analysis of variance (ANOVA) with 95% confidence limits ( α = 0.05). The standardized effects of the independent variables and their interactions on the dependent variable were also investigated by preparing a Pareto chart. The optimum values of the selected variables were obtained by solving the quadratic regression model, as well as by analysing the response surface contour plots. The optimum coded values of three test variables were computed as x 1 = 0.125, x 2 = 0.707, and x 3 = 0.107 by using a LOQO/AMPL optimization algorithm. The experimental conditions at this global point were determined to be pH 0 = 3.97, C 0 = 43.4 ppm, and t C = 68.7 min, and the corresponding Pb(II) removal efficiency was found to be about 100%.

Effect of Low Temperature Sonication on Orange Juice Quality Parameters using Response Surface Methodology

Freshly squeezed orange juice samples were sonicated at a constant frequency of 20 kHz for a range of processing temperatures (10–30 °C), amplitude levels (40–100%) and time (2–10 min) with pulse durations of 5 s on and 5 s off. Hunter colour values (L*, a* and b*), pH, oBrix, titratable acidity, cloud, non-enzymatic browning and ascorbic acid content were measured. Response surface methodology (RSM) based upon a three-factor, three-level Box–Behnken experimental design was used to determine the effect of independent variables. Under process conditions used in this study, no significant difference (p 0.92) to experimental data. Box–Behnken design and RSM was demonstrated to be an effective technique to model the effect of sonication on juice quality while minimising the number of experiments required.