جستجوی مقالات مرتبط با کلیدواژه « response surface methodology » در نشریات گروه « مهندسی شیمی، نفت و پلیمر »

Chemometrics science is effectively used for solving experimental problems and describing of experimental results in different fields using statistics and mathematics. Such applications of the method can be referred to solving the problems about optimization of the experimental methods. In the present research, ultrasonic irradiations was used for synthesis of zinc ferrite nanostructures. Also, starch as a green material was applied to reduce using of chemicals. Other novelty of the present study was application of the multivariate optimization method instead one-at-a-time usual methods. For achieving the purpose, at first the nanostructures were synthesized based on Box-Behnken design. Then, the results of X-ray diffraction were used as experimental responses for optimization of effective parameters on the synthesis of the nanostructures using response surface methodology. Finally, the optimized nanostructures were applied for investigation of electrocatalytic properties in tyrosine detection. The results showed the zinc ferrite nanostructures that were synthesized in the optimum conditions contain appropriate potential for trace analysis of tyrosine in complicated real samples.

Osmotic dehydration of fig fruits (cv. Sabz) in ternary solution of water, sucrose and sodium chloride at different solution concentrations, temperature and process durations were analyzed. A comparative approach was made between artificial neural network (ANN) and response surface methodology (RSM) to predict the mass transfer parameters. Results showed that all independent variables positively decreased the weight meaning that increasing each factor resulted in increasing weight loss and this relationship was linear. Osmo-dehydrated figs had better quality compared to samples without osmosis. All four independent variables explained 94% of the weight loss, 90% moisture content reduction and 89% of the solid gain. The determined optimum processing conditions were temperature of 60°C, sucrose concentration of 70%, sodium chloride concentration of 5% and immersion time of 5h. The results showed that properly trained ANN model is found to be more accurate in prediction as compared to RSM model.

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Considering water quality problems and strict rules established for drinking water treatment, there is an urgent need to use more effective and economical methods to remove natural organic matter from water. Meanwhile, membrane processes are one of the effective methods to remove these pollutants. In this way, in order to prepare a membrane with a high ability to remove pollutants, in the present study, the production and optimization of poly(vinyl chloride) (PVC) membranes with poly(ethylene glycol) (PEG) additives have been carried out.

PVC microporous membranes were prepared by nonsolvent-induced phase separation method. Influential parameters in the membrane fabrication, including the concentration of PVC and PEG and the composition of the coagulation bath were optimized using the response surface methodology (RSM). Meanwhile, tensile strength and porosity were considered as responses.

The obtained results showed that all the membranes had an asymmetric structure with finger like pores. It was also found that the tensile strength of the membranes increased with the increase in PVC concentration. The lowest tensile strength was related to the membrane made of 10.30% (by wt) of PVC, while the membrane made of 18.7 % (by wt) of PVC had the highest tensile strength. In addition, for the optimum membrane in which the concentration of PVC was 17.52% (by wt), the concentration of PEG was 5.87% (by wt) and the volume fraction of ethanol in the coagulation bath was 0.27, the tensile strength and porosity of the membranes were obtained as 5 MPa and 80.57, respectively. Furthermore, in the following, titanium dioxide nanoparticles (TiO2) were used to prepare the composite membrane under the aforementioned optimum conditions. The obtained results showed that the optimum membrane containing 2% (by wt) of nanoparticles had the highest humic acid separation efficiency with a value of 80%.

In various countries, strict rules are considered for reducing sulfur in the fuels. Oxidative desulfurization is known as one of the best complementary methods for the hydro-desulfurization. In this paper, using the response surface methodology, the effects of initial sulfur concentration in the naphtha fuel, reaction temperature, and reaction time on the sulfur conversion were investigated in the presence of zeolite supported zinc Oxide catalyst. </em>Experiments were conducted at the conditions as follows: T=303.15-323.15 K, t=20-40 min, and initial sulfur concentration=150-250 ppm. </em>Analysis of variance showed that the linear factorial model well fitted the experimental data. All the parameters as well as the interaction between reaction time and temperature affected the response, significantly. Maximum sulfur conversion of 90% was achieved at the temperature of 320 K, reaction time of 40 min, and initial sulfur concentration of 244 ppm.</em>

gels that have a low viscosity at the time of mixing and form a three-dimensional gel structure after some time delay can be applied successfully in controlling lost circulation. The hybrid gel consists of a cross-linked gel polymer as a continuous phase and an oil as an internal phase. The hybrid gel is cost effective and its properties can be controlled. This study consists of two parts, experimental investigation and empirical modeling using response surface methodology. a number of parameters such as initial gelation time, final gelation time, crosslinking rate and Final viscosity were defined and compared to evaluate the gel behavior under different conditions. First, the effect of pH, temperature and salinity on gel performance as well as the stability of the gel over time were investigated. Then, dynamic stability test for different gels was examined to measure the amount of pressure that the gel in the fractured core can withstand to prevent further fluid loss. Finally, the amount of gel rupture with time in HCL (15 and 28%) was investigated to evaluate the formation of damage of hybrid gel. The experimental results show that hybrid gels can have proper performance and application in industry to combat lost circulation due to their flexible viscosity response and non-damaging properties. response surface methodology(RSM) based on Box-Behnken design was utilized to identify a correlation for prediction of final viscosities of hybrid gel as a function of temperature, pH and salinity. The predicted model was obtained by solving the quadratic regression model. The value of correlation co-efficient (predicted R2 = 0.88) for the present mathematical model indicated good relation between experimental data and predicted values. Therefore, the proposed model predicts the viscosity of gel adequately within the limits of input parameters being used.

In this research work, the ability to use nanofibrous membrane as an absorbent filter was investigated. For this purpose, electrospinning of polyamide 6 (PA6) in formic acid was performed at different concentrations and the effect of polymer concentration, voltage and needle-to-tip distance on the morphology of the fibers was evaluated using the statistical method of response surface methodology (RSM). Based on the results of the statistical analysis, the optimal sample was selected with the minimum average fiber diameter (111 nm) at a concentration of 10% PA6, a voltage of 20 KV and a distance of 20 cm. Then, the effect of carbon nanotubes (CNT) incorporation into the fibers (at different percentages of 0.1, 0.2, and 0.5%wt) was studied. The porosity test showed an increase in the porosity of the samples with the addition of CNT. The results of the tensile test revealed that the maximum tensile strength and elongation up to the breaking point were obtained for the fibers containing 0.1% CNT. FTIR spectra depicted the characteristic peaks of amides and amine groups in PA6. Thermal analysis (TGA) showed that thermal stability increased with the addition of CNT. Finally, in the spectrophotometric test, the absorption of dye by the nanofibrous membrane was observed by prolonging time.