جستجوی مقالات مرتبط با کلیدواژه « optimization » در نشریات گروه « شیمی »

The effects of Dielectric Barrier Discharge (DBD) on crystal-sugar contaminated with Geobacillus  stearothermophilus   and Aspergillus niger was studied with combined variables of power (5–15 w), time (2-10 min), and voltage (15-22 kV). The total microbial loads of Gs (9×105) and An (9×104 CFU/g) loads were destructed (P ≤ 0.05) when the voltage and power were 22 Kv and ≥ 5 W. Additionally, their death values (D) were equal and below 1.18 min, respectively. Results showed that increasing voltage had at least 70% more effects on Gs sterilization than the time and power of DBD. Although the cold plasma has substantial destructive effects on the  cell membranes, DNA, and protein of microrganisms, Scanning Electron Microscopy (SEM) of A. niger,  and G.  stearothermophilus confirmed the disinfection process by changes happened in their sizes, configurations, and spores due to the cold plasma process. The DBD method (a non-thermal procedure) can be applied as a new antimicrobial practice to fully sterilized the purified crystal sugar and make it completely appropriate for pharmaceutical and baby food industry.

In a wind farm, the wake interference between wind turbines particularly upstream and downstream turbines is the main issue that leads to identifying the optimum configuration of the turbines. The two-dimensional CFD simulations of a solo wind turbine and turbine cluster were performed to determine turbine configurations that could boost the efficiency of wind farms. The efficiency of a turbine cluster is examined by arranging the two downstream turbines in eight relative positions to the upstream turbine in a V-shaped layout. The Kriging optimization technique was based on 8 design parameters that suggested optimum layout resulting in 21.96% augmentation in the cluster's average efficiency compared to the power coefficient (Cp) of a solo turbine. Furthermore, the optimum rotational direction of the downstream turbines in the optimized layout was examined through 4 sets of arrangements and it was revealed that the optimal rotational direction for the upstream turbine and the lower downstream turbine are clockwise rotating, whereas the best rotational direction for the upper downstream turbine is counterclockwise rotating. By analyzing the efficiency of five and seven turbine clusters at the optimum position, it was determined that the clusters of five and seven turbines, improve the average Cp by 22.6%, and 23.03%, respectively. Finally, the result of the HOMER-based economic analysis demonstrates that a 7-turbine cluster with more electrical production and lower Net Present Cost (NPC) than a 5-turbine cluster can be employed to meet the site load demand.

Considering the limitations of energy consumption and the increasing problems of pollution from low-quality fossil fuels and the need to increase the quality of these fuels by using oxygen additives such as Ethyl tert-butyl ether (ETBE) for their combustion, reviewing and optimizing the production processes of oxygen additives is of great importance. The goal of this study is to simulate-optimize the ETBE production which is used as an oxygenate gasoline additive in the production of gasoline from crude oil. The feed for the ETBE unit comprised two flows of hydrocarbon and ethanol. The Soave-Redlich-Kwong (SRK) equation of state for the vapor phase and the UNIQUAC activity coefficient model for the liquid phase have been used. In this work, at first, the reactive distillation process was simulated by HYSYS software for producing ETBE. Then, the coding was written using MATLAB software and the Genetic algorithm (GA). Both software have been linked simultaneously and the later optimization data was transferred and compared with HYSYS data. The objective function was reflected as the total annual income of ETBE production. The parameters of the objective function were optimized by GA. Optimization was made on decision variables of the objective function which included the output stream temperature of the heater (Tho), input stream temperature of the reactive distillation tower (Tti), output stream temperature of the cooler (Tco), and input stream feed pressure of the distillation tower (Pti). The results of GA optimization show that reboiler duty decreases by 10% as well as total annual profit increases by 15%. Additionally, the comparison of the present work with the findings of researchers reveals a good agreement.

The bioconversion of sweet sorghum bagasse as lignocellulosic biomass into bioethanol is a complex and challenging process. The present study focuses on optimizing the pretreatment, enzymatic hydrolysis, and fermentation processes during bioethanol production from the bagasse of a drought-tolerant and high-yield sweet sorghum genotype (ISCV 25264).A comparison of acid and alkali pretreatment methods on enhanced enzymatic saccharification of sweet sorghum bagasse indicated that alkali pretreatment with NaOH was more effective. Three independent variables including the NaOH concentration (2-4%), pretreatment time (10-40 min), and pretreatment temperature (80-120°C) were optimized using Response Surface Methodology (RSM) based on central composite design. Pretreatment optimization resulted in a glucose concentration of about 84 g/L during the enzymatic hydrolysis. Afterward, the key variables affecting the hydrolysis process, which included the substrate concentration (5-10%), time (20-70 h), and the temperature (38-50°C) of the hydrolysis reaction were optimized by RSM. Glucose concentration was increased to 93 g/L by using the optimized enzymatic hydrolysis parameters (substrate concentration of 10%, incubation time of 60 h, and incubation temperature of 50°C). Subsequently, Simultaneous Saccharification and Fermentation (SSF) and separate hydrolysis and fermentation (SHF) methods were performed for bioethanol production using Saccharomyces cerevisiae. The results indicated that the ethanol concentration after 48 h was higher under the SHF method (48.714 g/L), compared to SSF (29.582 g/L); however, this method was not commercially attractive due to the much longer total time for bioethanol production. Finally, optimization of the parameters during the SSF process (substrate and yeast concentrations of 30% and 4%, respectively) led to an ethanol concentration of 33 g/L. The optimization of the bioethanol production process in this research has created a platform for pilot-scale studies to investigate the feasibility of bioethanol production from sweet sorghum bagasse at the industrial level.

The plant-based extract can be used to synthesize silver nanoparticles (Ag NPs) as a reducing agent. In the present study, Oregano leaves’ extracts were extracted using ethanol to synthesize Ag NPs. The effects of different parameters such as the processing time, temperature, and stirring rate on the mean particle size, concentration, and zeta potential of the synthesized Ag NPs solutions were optimized using Response Surface Methodology (RSM). At the optimum condition, which includes processing time (30.48 min), temperature (70 ºC), and stirring rate (370.530 RPM), Ag NPs were obtained with 33 nm of the mean particle size, 76.109 ppm of concentration, and +17.2 mV of zeta-potential. In this condition, Ag NPs displayed high antibacterial activity against Gram-negative and Gram-positive bacteria. In addition, the maximum antioxidant activity of 11.7% was obtained at optimum synthesizing conditions.

The extraction of keratin from natural feathers has been studied for its use in various cosmetics and drug delivery applications. There are various reducing agents to dissolve the hard keratin such as sodium dodecyl sulfate and 2-mercaptoethanol, in the present work, a novel extraction methodhas been developed using sodium sulphite, sodium bisulphite, and sodium dodecyl sulfate in the presence of urea, 2-mercaptoethanol, Ethylenediaminetetraacetic acid (EDTA), and thiourea. To increase extraction yield, the weight of feathers, time of incubation, pH, and temperature were investigated using a Central Composite Design and Mixture plan for Optimization. With the present process, we evaluated the apport of keratin treatment and extraction techniques utilizing sodium sulphite, sodium bisulphite, and sodium dodecyl sulfate in the presence of urea, 2-mercaptoethanol, Ethylenediaminetetraacetic acid (EDTA), and thiourea. The percentage yield and keratin concentration were measured using UV-Vis absorbance, Bradford, and Biuret assays. Then, the protein profile and their functional groups were characterized using Sodium Dodecyl Sulfate-Polyacrylamide Gel Electrophoresis (SDS-PAGE) and Fourier Transform Infrared Spectroscopy (FTIR). The purpose was to compare the different procedures in terms of keratin protein quality and quantity, as well as their cost-effectiveness, and to determine the optimum conditions for the keratin extraction process. The results proved that the yield of white chicken feathers keratin (81.2 %) increased using sodium sulphite (1M), sodium bisulphite (0.1 M), and Sodium Dodecyl Sulfate (0.1 M).  The highest protein production was measured at 80°C in 10 h with 5 g of feathers at pH 10. This process of keratin extraction can be used from the laboratory to industrial production with high recoverability and stable properties.

In this study, the effects of ethanol-butanol/gasoline blends (EB0%, EB10%, and EB20%) on spark ignition engine performance and emissions were investigated for the different compression ratios (6.0:1, 8.0:1, and 10.0:1), and different load conditions (2kW, 4kW, and 6kW). Based on the experimental results, the response surface methodology has been used to develop a model and to estimate the outputs of brake thermal efficiency, brake-specific energy consumption, carbon monoxide, hydrocarbon, and oxides of nitrogen. The optimum operating conditions, 9.970% of the ethanol-butanol blend, 10.0:1 compression ratio, and 6 kW of engine load were obtained through the desirability approach of response surface methodology. Brake thermal efficiency, brake-specific energy consumption, carbon monoxide, hydrocarbon, and oxides of nitrogen at optimum conditions are 35.041 %, 0.493 kg/kWh, 0.217 %, 213.575 ppm, and 1263.787 ppm, respectively. Moreover, the developed models have higher R2 values near 1, and the optimum responses are obtained with a higher desirability value of 0.768. Ethanol-butanol/gasoline blends improved the brake thermal efficiency, carbon monoxide, and hydrocarbons. Whereas it increased the brake-specific energy consumption and oxides of nitrogen.  In addition, the validation test results illustrate that the acceptable error rate between optimized values obtained through the desirability approach of response surface methodology and experimental values is below 7%.

In this study, ZnO/Fe2O3 and ZnO/activated carbon nanoparticles have been employed as efficient adsorbents for the removal of ibuprofen antibiotic from aqueous solutions. Nano-adsorbents were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) analyses. The results illustrate that the ZnO/Fe2O3 and ZnO/activated carbon nanocomposite were successfully synthesized. Optimization of the removal of ibuprofen was scrutinized via response surface methodology (RSM) based on central composite design (CCD). The process parameters, such as pH (4-6), contact time (10-20 min), nanoparticles dosage (0.02-0.04 wt.%), and nano-adsorbent type (ZnO/Fe2O3 and ZnO/activated carbon) were investigated in batch experiments. Within the range of the chosen experimental conditions, the optimized values of pH, contact time, nanoparticles dosage, and nano-adsorbent type were obtained to be 5.48, 17.22 min, 0.03 wt.%, and ZnO/Fe2O3, respectively. According to the optimum condition, the anticipated Ibuprofen removal was 83.74% and the empirical value was 85.42%. The high values of R2 95.96 and R2 adj 93.78 demonstrate that the fitted model shows a satisfactory accord with the anticipated and empirical Ibuprofen removal. Adsorption kinetics and isotherms are well-fitted with pseudo-second-order and Langmuir models, respectively, meaning that monolayer adsorption of Ibuprofen to the adsorbent's surface is controlled by electrostatic interactions, stacking of π-π, and linkages of hydrogen

The oil extraction from Bauhinia variegata seeds to produce biodiesel was performed using microwave-assisted extraction. About, 9 combinations of solvents were employed, and found that hexane-acetone (80:20 mL) gave a better yield, and the maximum bio-oil yield was found to be 29.03±0.61 % at the optimal condition of 9 min of processing time with a supply of 240 W and 12 mL/g of solvent volume. The presence of functional groups in the Bauhinia variegata seed oil was identified using FT-IR analysis and the fatty acid composition was analyzed using GC-FID. The results reveal a predominant fatty acid (C18:2) present in the group was linoleic (about 43.4%). From scanning electron microscopy analysis it was observed that the microwave treatment promoted rapid extraction of oil, as a structure of raw materials was ruptured. The physicochemical properties of the oil were determined as per ASTM D6751 and found that a free fatty acids value of less than one can be directly treated for the transesterification process. The results from this study suggest that MAE is an efficient and eco-friendly method to extract oil from Bauhinia variegata seeds in bio-diesel production.

The study aimed to optimize the corrosion inhibition performance of an extract from Pilliostigma thoningii stem bark on mild steel in 1M HCl environment using Response Surface Methodology (RSM). The optimal inhibitor concentration, temperature, and reaction time were found to be 1.0 g/L, 333 K, and 1 hour, respectively, resulting in an inhibition efficiency of 93.75%. The inhibitor's efficacy was confirmed through various analytical methods, including SEM, FTIR, and UV-Visible spectroscopy. The results suggest that the experimental and predicted data are in reasonable agreement, showing that the quadratic model was the fittest for optimizing the inhibition process. The study identified 33 compounds through GC-MS, with PT-1, PT-2, and PT-3 being the major compounds. Quantum chemical calculations and molecular dynamics simulations further confirmed the effectiveness of the three selected inhibitor molecules, with PT3 being the most effective. The study concludes that Pilliostigma thoningii stem bark extract has the potential to be an effective corrosion inhibitor for mild steel in acidic environments.

In this study, the micellar-enhanced ultrafiltration (MEUF) separation process was employed to determine the removal percentage of lead ions from aqueous solutions. The effect of diverse parameters, such as the initial concentration of lead (200-400 mg/l), operating pressure (2-4 bar) and molar concentration ratio of the surfactant SDS to the metal (5-10), was investigated using the Box-Behnken design (BBD) of response surface methodology (RSM). The number of experiments designed by this scheme was 15 and the importance of the effective parameters and their binary interactions were evaluated using the analysis of variance (ANOVA). The obtained results showed that the proposed model has optimal accuracy and efficiency in the prediction of the lead rejection percentage. The responses predicted by the model showed that the MEUF process could lead to a high rejection rate of Pb(II) ions (99.90 %) at optimal conditions.

The study describes the adsorption of Lead ion from aqueous solution using Sugarcane bagasse. Bagasse is a fibrous residue from Sugar mills, is not easily biodegradable posing disposal challenges. Given its abundance in the sugar producing regions of Nigeria, there is continued need to find other alternative uses. The objective of this study was to investigate the potential use of sugarcane bagasse-based adsorbents for removing Pb, from contaminant water. Sugarcane bagasse was used for removal of Pb ion from aqueous solutions as an efficient adsorbent. The response surface methodology (RSM) was applied for experimental design of adsorption from aqueous solutions. The effect of three independent variables including contact time, Adsorbent dosage and Pb ion concentration on the percentage removal (R (%) was studied. For this purpose, 13 runs of experiments that was designed by the Design–Expert software were performed. The optimum conditions for contact time, Adsorbent dosage and Pb ion concentration were found as 4.5hrs, 8g and 100ppm, respectively. At these conditions, percentage removal was to be 99.2%. It is evident that bagasse-based adsorbents can effectively remove Pb, from contaminated water. It is therefore recommended that the bagasse-based adsorbents can be utilized to remove Pb from contaminated water but more studies need to be conducted with actual contaminated water from various sources to determine their efficacy as adsorbents.

The purpose of this study was to use a hydro-ethanolic solvent to extract natural color extract as effectively as possible from Calendula arvensis flower petals. The effects of ethanol volume, extraction time, and solvent/material ratio on the efficacy of Calendula arvensis flower petal extractives by ultrasonic extraction at 50 kHz and room temperature were investigated. Total phenol content (TPC) and color power were used to quantitatively describe each extract. Using Response Surface Methodology (RSM), the extraction procedure was optimized, and extraction effectiveness was increased (TPC, color power). Different ethanol-to-water ratios were employed in the experiments. Through a variance analysis, the effectiveness of the extraction procedure was established (ANOVA). The maximum extraction efficiency of the hydro-ethanolic extraction (28.21%), the polyphenol content (779.11 mg GAE/g extract), and the color power (42) were quantified using a 30 min treatment time, a 60:40 ethanol:water ratio, and a 15 mL/g solvent/material ratio. The results obtained show that ultrasonic-assisted extraction is a successful technique for extracting natural color from Calendula arvensis.

The formation of unwanted oil emulsions during the production, transportation, and processing of crude oil is a major challenging issue. This causes serious technical problems and, subsequently, huge financial losses, which indicate the importance of their separation. The present work investigated the influence of an efficient oil-soluble demulsifier and temperature on the Demulsification Efficiency (DE) of water-in-crude oil emulsions through the bottle test method. The Central Composite Design (CCD) based on Response Surface Mythology (RSM) was applied to design the experiments and optimize the demulsification process. Based on the experimental results, a reduced quadratic model was developed using CCD. In addition, the analysis of variance (ANOVA) was used to evaluate the significance of the developed model and operational parameters. It was found that the P-value of the DE model was less than 0.0001, which confirms the considerable significance of the developed model. Moreover, R2, adj-R2, and pred-R2 were 98.89, 98.15, and 94.34%, which indicates the high accuracy of the proposed model. The result showed that the effect of the demulsifier at low temperatures (25-50 oC) was significantly weak on the separation efficiency of the studied emulsions. In this case, the maximum water removal from the oil emulsions reached approximately less than 50%. In addition, the results demonstrated that the maximum interaction effect between parameters was observed by adding 20-25 ppm of the demulsifier at 75 °C. Moreover, the demulsification efficiency was obtained by more than 75%. Meanwhile, the subsequent addition of the demulsifier to the crude oil emulsions at concentrations greater than 25 ppm has almost not changed the efficiency of the process. Finally, the numerical optimization results obtained by CCD indicated that the maximum separation efficiency of 80.65% was achieved under the following optimal conditions: demulsifier dosage at 25 ppm and temperature at 75 °C.

The non-toxic BSA-based NanoParticles (NPs) are developed without any additives with hydrothermal SubCritical Water Treatment (SCWT). The optimum BSA-based NPs are gained by applying Response Surface Methodology (RSM) based on particle size, zeta potential, and polydispersity. The SCWT conditions are optimized in terms of these three dependent variables, which have significant impacts on the BSA-based NPs application. The optimum BSA-based NPs prepared with 2.73% (w/v) of initial BSA solution concentration, the lowest initial concentration that is used to synthesize BSA-based NPs by now. The SCWT condition of 173 °C and 2.07 min of SCWT holding time shows that the zeta potential of -38.87 mV with the finest particle size and PI (147.32 nm and 0.24, respectively) is the optimized composition. The fabricated BSA-based NPs are characterized by the UV-vis, screening electron microscope (SEM), and stability assessment study.

Studies on the epoxidation of fatty acids have garnered much interest in recent years due to the rising demand for eco-friendly epoxides derived from vegetable oils. This study aims to optimize the process parameters of epoxidation of palm oleic acid via an in situ peracid mechanism with an applied homogenous catalyst. Oleic acid was epoxidized using performic acid-generated in situ through the reaction between hydrogen peroxide and formic acid when sulfuric acid was applied as a catalyst. The optimum reaction condition of epoxide was at the temperature of 45°C, the molar ratio of formic acid to oleic acid at 1.64:1 and the molar ratio of hydrogen peroxide to oleic acid at 2:1. Lastly, a mathematical model was developed using the numerical Runge Kutta-4th Order method. In the model, the method was applied with a genetic algorithm optimization to determine the process model that fit the experimental data using MATLAB software. After 100 iterations, the reaction rate constant for epoxidized oleic acid production was: k11 = 1.9305 L/mol. min, k12 =15.2284 L/mol. min, k21 = 0.0570 L/mol. min, k31 = 0.0106 L/mol. min. Overall, epoxidized oleic acid was successfully produced by in situ performic acid mechanism with 80% relative conversion to oxirane.