Application of response surface methodology for the biosorption of copper using Rhizopus arrhizus

Response surface methodology was used to study the cumulative effect of the various parameters namely, initial copper ion concentration, pH, temperature, biomass loading and to optimize the process conditions for the maximum removal of copper. For obtaining the mutual interaction between the variables and optimizing these variables, a 2(4) full factorial central composite design using response surface methodology was employed. The analysis of variance (ANOVA) of the quadratic model demonstrates that the model was highly significant. The model was statistically tested and verified by experimentation. A maximum copper removal of 98% was obtained using the biosorption kinetics of copper under optimum conditions.     

Application of response surface methodology (RSM) for optimization of nutrient supplementation for Cr (VI) removal by Aspergillus lentulus AML05

Response surface methodology (RSM) involving central composite design (CCD) was employed to optimize the concentrations of different media components for growth and Cr (VI) removal (100 mg l(-1) initial concentration) by Aspergillus lentulus AML05 at pH 6.5. The interaction between five variables i.e. glucose, K(2)HPO(4), MgSO(4), yeast extract, NH(4)NO(3) was studied and modelled. The statistical analysis of the results showed that in the range studied, yeast extract had a significant effect on Cr (VI) removal and production of fungal biomass. The optimum combination predicted via RSM was confirmed through experiment, whereby almost complete removal (99.8%) of Cr (VI) was obtained within 120 h. The validation of these results in terms of field applicability was also tested by treating industrial effluent supplemented with key media components.     

Nanocellulose fibers for biosorption of cadmium,nickel, and lead ions from aqueous solution

Nanocellulose fibers were prepared using physico-chemical treatment of rice straw, characterized and explored for the remediation of some toxic metals from wastewater. Nanocellulose fibers were found to have long rod-like elongated nano fibrillated morphology with average grain size 6 nm. The prepared nanocellulose fibers (0.5 g) in batch experiments showed removal efficiency of 9.7 mg/g Cd (II), 9.42 mg/g Pb(II), and 8.55 mg/g Ni (II) ions from 25 mg/l of metal solution. The sorption process fitted well to both Freundlich and Langmuir isotherms [(R²) Cd (II): 0.92, 0.95; Pb(II): 0.94, 0.97 and Ni (II): 0.97, 0.98]. The regeneration studies signify that nanocellulose fibers can be successively used up to three cycles of regeneration. Nanotech reinforcement to native cellulose significantly enhanced metal removal efficiency compared to rice straw and cellulose fibers, provides new avenues as cost effective, environment-friendly green remediation or can be used as a pre-treatment step prior to chemical decontamination methods for toxic metals.     

响应表面法在薄壁构件耐撞性优化设计中的应用研究

汽车结构的耐撞性及碰撞吸能优化是现代汽车工业重要的研究内容。耐撞性的优化涉及材料与结构的众多参数。传统的设计、碰撞仿真及试验往往只能在一定程度上改善结构的碰撞性能而无法达到限定条件下的最优状态。利用国际上近年来新发展起来的一种优化理论方法--响应表面法,结合传统的优化手段以及非线性有限元程序对薄壁构件的耐撞性问题进行了优化研究。耐撞性优化的结果表明,该方法具有较高的精确性和有效性。     

曲面响应法在等离子喷涂WC-12Co涂层工艺优化中的应用

为了提高WC-12Co涂层质量,采用曲面响应法对等离子喷涂WC-12Co涂层的工艺参数进行优化,以涂层显微硬度为评价指标,设计了以电流、氩气流量和喷涂距离三因素的Box-Behnken实验模型.利用方差分析三因素的显著性及交互作用,采用BP神经网络建立3×9×1的神经网络模型,并与回归模型预测结果进行比较.通过实验方法对优化参数进行验证,同时分析了不同喷涂距离对涂层组织与性能的影响.研究表明:回归模型复相关系数R2为0.979 9,BP神经网络的复相关系数R2为0.999 1;神经网络的平均相对误差为0.46%,低于多项式回归模型的平均相对误差1.56%.喷涂距离对涂层显微硬度影响最为显著,最优工艺参数为:电流I=390 A,氩气流量QAr=2 500 L/h,喷距d=130 mm,能够预测的最大硬度为1 336.9HV0.5.     

Identification and characterization of Leucobacter sp. N-4 for Ni (II) biosorption by response surface methodology

In the present study, batch experiments were carried out to characterize and optimize the removal process of Ni (II) by a nickel tolerant strain Leucobacter sp. N-4, which was isolated from the soil samples. The effects of operating parameters with respect to initial solution pH (3.0-6.5), initial nickel concentration (50-100mg/L) and biomass dosage (1-10 g/L) on Ni (II) biosorption were investigated by response surface methodology (RSM). The maximal Ni (II) removal efficiency (nearly 99%) was achieved under the following conditions: pH 4.75, biomass dosage 5.38 g/L and initial Ni (II) concentration 53.6 mg/L. The adsorption-equilibrium data fitted well with both Langmuir and Freundlich isotherms. The monolayer adsorption capacity of biomass obtained from Langmuir isotherm was about 19.6 mg/g. Infrared spectrometer (IR) results showed that chemical functional groups (e.g. -NH(2), -OH and COO-M) of the biomass should be the active binding sites for Ni (II) biosorption from aqueous solutions.     

Composition optimization of extruded starch foams using response surface methodology

Response surface methodology (RSM) was used to analyse the effect of polyvinyl alcohol (PVA) and calcium carbonate (CaCO₃) on the objective attributes (shipping bulk density, radial expansion ratio, compressibility and spring index) of a biodegradable cushioning extrudate. A rotatable central composite design (CCD) was used to develop models for the objective responses. The experiments were run at 105°C with a feed rate of 27.8 l/h, screw speed 500 r.p.m. and die diameter 3.92 mm. Responses were most affected by changes in polyvinyl alcohol (PVA) levels and to a lesser extent by calcium carbonate (CaCO₃) levels. Individual contour plots of the different responses were overlaid, and regions meeting the optimum shipping bulk density of 6.00 kg/m³, radial expansion ratio of 3.30, compressibility of 43.71 N, and spring index of 0.91 were identified at the PVA level of 20.23% and the CaCO₃ level of 7.89%, respectively. Copyright © 2004 John Wiley & Sons, Ltd.     

Systematic evaluation and optimization of crystallization conditions for an ethanol-templated ZSM-5 zeolite using response surface methodology

The present study aimed to systematically evaluate and optimize the crystallization conditions of ZSM-5 templated by ethanol in a 5-liter stirred autoclave. Response surface methodology was applied to investigate the effects of independent variables of temperature, time, and seed content on the responses of yield, crystallinity, and the specific surface area. A variety of characterization techniques, including XRD, FTIR, FESEM, EDX, and N₂ adsorption/desorption analyses, were performed to fully assess the effects of the parameters on the textural and structural properties of ZSM-5. The study of variance results showed that time played the most prominent role in the ethanol-templated synthesis of ZSM-5. The crystallization time and temperature had significant quadratic effects on the responses. It was also shown that the seed by itself exerted no noticeable influence on the responses and had only a slight interaction with time, suggesting that the surface integration reaction is mainly the rate-controlling step. Moreover, the findings revealed that seed addition led to increased surface roughness and particle agglomeration and could reduce the surface area at sufficiently high reaction times. Eventually, a highly pure and crystalline ZSM-5 with a surface area of over 430 m²/g was obtained at an optimum temperature of 169 °C within 34 h.     

Preparation and optimization of doxorubicin-loaded albumin nanoparticles using response surface methodology

Background: The objective of this work was to optimize the preparation of doxorubicin-loaded albumin nanoparticles (Dox-A-Nps) through desolvation procedures using response surface methodology (RSM). A central composite design (CCD) for four factors at five levels was used in this study.

Method: Albumin nanoparticles were prepared through a desolvation method and were optimized in the aid of CCD. Albumin concentration, amount of doxorubicin, pH values, and percentage of glutaraldehyde were selected as independent variables, particle size, zeta potential, drug loading, encapsulation efficiency, and nanoparticles yield were chosen as response variables. RSM and multiple response optimizations utilizing a quadratic polynomial equation were used to obtain an optimal formulation.

Results: The optimal formulation for Dox-A-Nps was composed of albumin concentration of 17?mg/ml, amount of doxorubicin of 2?mg/ml, pH value is 9 and percentage of glutaraldehyde of 125% of the theoretic amount, under which the optimized conditions gave rise to the actual average value of mean particle size (151?±?0.43?nm), zeta potential (?18.8?±?0.21 mV), drug loading efficiency (21.4?±?0.70%), drug entrapment efficiency (76.9?±?0.21%) and nanoparticles yield (82.0?±?0.34%). The storage stability experiments proved that Dox-A-Nps stable in 4°C over the period of 4 months. The in vitro experiments showed a burst release at the initial stage and followed by a prolonged release of Dox from albumin nanoparticles up to 60?h.

Conclusions: This study showed that the RSM-CCD method could efficiently be applied for the modeling of nanoparticles, which laid the foundation of the further research of immuno nanoparticles.     

Modelling and optimization of a GMA welding process by genetic algorithm and response surface methodology

The welding process, due to its complexity, has relied on empirical and experimental data to determine its welding conditions. However, trial-and-error methods to determine optimal conditions incur considerable time and cost. In order to overcome these problems, a genetic algorithm and response surface methodology have been suggested for determining optimal welding conditions. First, in a relatively broad region, near-optimal conditions were determined through a genetic algorithm. Then, the optimal conditions for welding were determined over a relatively small region around these near-optimal conditions by using response surface methodology. In order to give different objective function values according to the positive or negative response from the set target value in the optimization problem, a desirability function approach was used. Application of the method proposed in this paper revealed a good result for finding the optimal welding conditions in the gas metal arc (GMA) welding process.     

优化米曲霉固体发酵产果胶酶及产物酶学性质

以麸皮为基质,橘皮粉添加量、氮源、培养基初始含水量和发酵时间为因子,采用响应面法的中心组合设计,对影响米曲霉(Aspergillus oryzaeJL14)固体发酵产果胶酶的条件进行了优化.结果表明,橘皮粉、硫酸铵的最适添加量分别为13.2%和2.3%,初始含水量为63.5%,发酵时间为77.0 h,米曲霉果胶酶产量最大预测值达316.4 U/g发酵产物,实验验证值为310.7 U/g发酵产物,是基础培养基酶产量的3.3倍.该米曲霉果胶酶(PG)的最适温度为50℃,Tm为55.9℃,其热稳定性较差;最适pH为4.0,属于嗜酸性果胶酶,在pH 5.0~8.0范围内稳定性较好,处理1 h后残余酶活均在80%以上.PG的Km和Vmax分别为7.06 mg/mL和62.5μmol-1.min.mL-1.PG能快速降低果胶溶液的黏度.该研究为提高橘皮利用率和酶法生产高品质果胶低聚糖奠定基础.     

Investigation of nickel(II) biosorption on Enteromorpha prolifera: optimization using response surface analysis

In this study, the biosorption of nickel(II) ions on Enteromorpha prolifera, a green algae, was investigated in a batch system. The single and combined effects of operating parameters such as initial pH, temperature, initial metal ion concentration and biosorbent concentration on the biosorption of nickel(II) ions on E. prolifera were analyzed using response surface methodology (RSM). The optimum biosorption conditions were determined as initial pH 4.3, temperature 27 degrees C, biosorbent concentration 1.2 g/L and initial nickel(II) ion concentration 100 mg/L. At optimum biosorption conditions, the biosorption capacity of E. prolifera for nickel(II) ions was found to be 36.8 mg/g after 120 min biosorption. The Langmuir and Freundlich isotherm models were applied to the equilibrium data and defined very well both isotherm models. The monolayer coverage capacity of E. prolifera for nickel(II) ions was found as 65.7 mg/g. In order to examine the rate limiting step of nickel(II) biosorption, such as the mass transfer and chemical reaction kinetics, the intraparticle diffusion model, external diffusion model and the pseudo second order kinetic model were tested with the experimental data. It was found that for both contributes to the actual biosorption process. The pseudo second order kinetic model described the nickel(II) biosorption process with a good fitting.     

Statistical optimization of the electrospinning process for chitosan/polylactide nanofabrication using response surface methodology

In this study, chitosan/polylactide (CP) blend solutions in trifluoroacetic acid as a co-solvent with different blend ratio were electrospun. Effects of different CP ratio and process parameters on the diameter of electrospun nanofibers were experimentally investigated. The fiber morphology and the distribution of fiber diameter were investigated by scanning electron microscopy. Response surface methodology (RSM) was used to define and evaluate a quantitative relationship between electrospinning parameters, average fiber diameters and its distribution for each chitosan–polylactide ratio. Applied voltage and polymer solution extrusion rate are the process variables which control the fiber diameter at similar spinning distances (15 cm). Fiber diameter was correlated to these variables by using a second-order polynomial function. The fibers were of diameter ranging from 94 to 389 nm. The predicted fiber diameters were in good agreement with the experimental results. Contour plots were obtained to identify the processing variables suitable for producing nanofibers. It was concluded that ratio of polylactide and chitosan in the blend polymer played an important role to the diameter of fibers and standard deviation of fiber diameter. The processing factors were found statistically significant in the production of nanofibers.     

Enhancing surface layer properties of an aircraft aluminum alloy by shot peening using response surface methodology

Shot peening leads to local plastic deformations in the near-surface regions, which result in the development of residual stress and the improvement of surface hardness in the aerospace structural components. These properties can be enhanced by careful selection of the peening parameters. 2124-T851 aluminum alloy is widely used in the aerospace industry due to its high specific static strength. In this study, a response surface methodology is presented to optimize the surface properties of microhardness and residual stress. The effects of four peening parameters (nozzle distance, pressure, impact angle, and exposure time) on microhardness and residual stress are investigated. Box–Behnken design, a popular second-order response surface design, is employed to systematically estimate the empirical models of microhardness and residual stress in terms of the four parameters. Based on the estimated models, optimum peening conditions are recommended by using the desirability function approach, which is the most popular technique for optimizing multiple responses. Additionally, to verify the validity of the optimal conditions obtained from experimental results, metallurgical analyses of the shot-peened aluminum alloy were conducted with respect to hardness, residual stress, surface morphology, X-ray diffraction analysis, and surface roughness.     

The optimization of Cr(VI) reduction and removal by electrocoagulation using response surface methodology

In this study Response Surface Methodology (RSM) was employed to investigate the effects of different operating conditions on the removal of hexavalent chromium (Cr(VI)) by the electrocoagulation with stainless steel electrodes. Central Composite Design (CCD) was used for the optimization of the electrocoagulation process and to evaluate the effects and interactions of process variables: applied electric current, electrolyte concentration and application time on the removal of Cr(VI). A sample of metal finishing industry wastewater having a high Cr(VI) concentration of 1470 mg/L was used in the experimental study. The optimum conditions for complete (100%) Cr(VI) removal were established as 7.4A applied electric current, 33.6 mM electrolyte (NaCl) concentration and 70 min application time. The amount of sludge produced under the conditions optimized based on the results from the model was lower than the amount generated by chemical treatment with FeSO(4).7H(2)O and non-hazardous in nature.     

Prediction of nanofiber diameter and optimization of electrospinning process via response surface methodology

Response surface methodology (RSM) was used to obtain a more systematic understanding of the electrospinning conditions of polyamide 6 solutions. This method was used to establish a quantitative basis for the relationships between the electrospinning parameters such as applied electric field, the polymer concentrations, the rate of injection and nozzle-collector distance with the diameter of the produced nanofibers, and to predict the optimum conditions for electrospinning to produce nanofibers with controlled size. A response function was empirically determined by central composite design (CCD) using fiber diameter as an observed response and the electrospinning parameters as variables. The relationship between the response and the variables is visualized by a response surface or contour plots. The study of the graphical representations of contour plots, prediction formulas and prediction profiler can predict the operating conditions necessary to generate nanofibers with the desired diameters.     

响应面法优化联苯聚酰胺中空纤维复合膜制备工艺

应用响应面法优化3,3 ',5,5'-联苯四甲酰氯(BTEC)和间苯二胺(MPDA)界面聚合工艺中各影响因素(水相单体浓度、有机相单体浓度、聚合时间以及水相浸没时间),研究各影响因素及其交互作用对膜分离性能的影响.通过中心组合设计实验,并采用回归分析拟合得到二次方模型.结果发现BTEC浓度、MPDA浓度、聚合时间和水相浸没时间对脱盐率的影响显著性依次降低.BTEC和MPDA单体浓度的交互作用对膜脱盐率影响最显著,其次是MPDA浓度与聚合时间的交互作用,而BTEC浓度与水相浸没时间的交互作用最弱.最优操作参数:MPDA浓度9.1 g/L、BTEC浓度1.2 g/L、水相浸没时间65 min、聚合时间123 s,预测脱盐率为99.10％,而在此条件下实际值为98.97％,二者十分接近.在此条件下得到致密均一的聚酰胺复合膜.     

葡萄糖碳化物/海泡石复合材料制备工艺及响应面法优化

以葡萄糖和天然海泡石为原材料,利用水热碳化法制备了新型葡萄糖碳化物/海泡石复合材料,冷冻真空干燥法干燥样品。利用X射线衍射分析(XRD)、红外吸收光谱(IR)、扫描电镜(SEM)、比表面积(BET)对样品进行了表征,选择亚甲基蓝作为吸附质考察其吸附性能,并通过单因素和响应面法优化了材料制备的工艺。实验结果表明,复合材料制备最优工艺条件为:葡萄糖与海泡石质量比为1.49∶1.0、碳化时间为7.33 h(440 min);碳化温度为175℃,对亚甲基蓝的最优吸附量为45.22 mg/g;各因素对复合材料吸附亚甲基蓝性能的影响顺序为:碳化时间>碳化温度>葡萄糖与海泡石质量比。