Optimization of silver cementation yield in fixed bed reactor using factorial design and central composite design

This work deals with cementation of silver onto iron grid in fixed bed reactor. The influence of several parameters is studied namely: initial concentration of silver [Ag⁺]₀, flow rate, solution pH, and mass of iron. Moreover, their influence on the yield of the reaction of cementation is investigated statistically by the experimental design in view of industrial application. The estimation and the comparison of the parameter's effects are realised by using two‐level factorial design. The analysis of these effects permits to state that the most influential factor is the mass of iron with an effect of (+5.642), the second in the order is the initial concentration of silver ions (Ag⁺) with an effect of (+4.005), the third is the flow rate of the electrolytic solution with an effect of (+3.824). A central composite design methodology is employed to determine the optimum conditions for a silver cementation yield onto iron grid. For this end, the experimental results were approximated by a second‐order model as well as the surface contour plots and surface responses are drowned. The optimal conditions found for initial silver concentration, such as a flow rate, pH of the solution and mass of iron, are respectively: 21.25 mg/L, 4.43 L/min, 3.6 and 50 g. Under these conditions, the obtained silver cementation yield is 96.851%.     

中心组合设计响应面法优化烟梗提取工艺

为了提高造纸法再造烟叶原料烟梗的提取率,以水为溶剂,以提取时间、提取温度、液料比进行3因素5水平的中心组合设计,采用响应面法优化烟梗提取参数,建立数学模型并进行验证。结果表明,最优工艺条件为：提取温度59℃,提取时间45min,液料比9．1：1,对最佳工艺条件提取率的预测值为38．33％,实测值为38．03％,相对误差仅为0．78％。     

星点设计-效应面优化法优化阿司匹林肠溶片的包衣工艺

目的：采用星点设计一效应面优化法优化传统包衣锅制备阿司匹林肠溶片包衣工艺,提高其包衣效率。方法：通过筛选雾化压力、蠕动泵转速及枪一床距离3个工艺参数确定各因素水平,安排实验,结果以包衣效率为指标考察。结果：优化后的包衣工艺可有效的进行包衣。结论：星点设计一效应面优化法可利用最少的实验次数得到优化后的包衣工艺。     

中心复合实验优化竹黄半纤维素水解的工艺研究

以戊糖收率和水解底物失重率为评价指标,采用中心复合实验设计法对酸性亚硫酸氢钠(ASB)预水解竹黄制备戊糖工艺进行了优化.研究结果表明,各因素对戊糖收率的影响显著性顺序为硫酸质量浓度(X3)＞亚硫酸氢钠质量浓度(X4)＞反应时间(X2)＞反应温度(X1);对水解底物失重率的影响显著性顺序为反应温度(X1)＞硫酸质量浓度(X3)＞反应时间(X2)＞亚硫酸氢钠质量浓度(X4).当固液比(W/V)为1∶5时,ASB预水解最佳工艺条件为:水解温度为171.1℃,水解时间为37 min,硫酸质量浓度为13.92 g/L,亚硫酸氢钠质量浓度为13.84 g/L,在此条件下得到的戊糖收率为83.93％,底物失重率为29.36％.通过验证实验表明,该设计模型具有良好预测性.     

Optimization of transesterification of castor oil with ethanol using a central composite rotatable design (CCRD)

In the present study, the synthesis of fatty acid esters from castor oil using an alkaline catalyst was optimized. The variables reaction time, catalyst amount and oil:ethanol molar ratio were studied using a central composite rotatable design. The effects and significance of the models on the response variable and on ethyl biodiesel yield derived from pure castor oil were evaluated using a response surface curve and analysis of variance. All the variables significantly affected the reaction yield, the amount of catalyst being the most effective. The highest yield was obtained using an oil:ethanol molar ratio of 1:11, 1.75% KOH and a reaction time of 90 min.     

Investigations of the effects of temperature and initial sample pH on natural organic matter (NOM) removal with electrocoagulation using response surface method (RSM)

The removal of natural organic matter (NOM) from surface water by electrocoagulation (EC) was studied using response surface method (RSM). Factors used in the empirical model were electric charge per liter, initial pH and temperature. Relevant square and interaction terms of factors were studied. Based on analysis of variance (ANOVA), the model fitted well with dissolved organic carbon (DOC) reduction, aluminum dissolving and pH changes. UV 254 nm absorbance removal was moderately predicted. According to results, temperature affected significantly the dissolving rate of aluminum electrodes. Initial DOC concentration of the surface water was 18.35 mg/l. Maximum DOC removal of 80.4% was obtained when high electric charge per liter (144 C/l), low pH (4.3) and high temperature (295.15 K) were used. However, high DOC removal of 76.2% was predicted also when water temperature was only 275.15 K. Effect of temperature on NOM removal was minor as compared to the effects of electric charge per volume and the initial pH. EC neutralized pH during the EC treatment and had little impact on the conductivity of the water. According to the results, EC can be used for NOM removal during cold water period in Nordic countries.     

复合桩基优化设计方法与工程验证

提出用基于 Geddes应力解的分层总和法计算桩群分担荷载所引起的地基沉降 ,用基于 Boussinesq解的分层总和法计算承台下土分担的荷载所引起的地基沉降 ,将两者之和作为桩基沉降量。结合一个具体的工程将该方法计算的沉降量和其它方法计算的沉降量及实测值进行对比 ,通过研究沉降量与各种因素的关系 ,对复合桩基的优化设计进行了探讨。     

Synergistic optimization framework for the process synthesis and design of biorefineries

The conceptual process design of novel bioprocesses in biorefinery setups is an important task,which remains yet challenging due to several limitations.We propose a novel framework incorporating superstructure optimization and simulation-based optimization synergistically.In this context,several approaches for superstructure optimization based on different surrogate models can be deployed.By means of a case study,the framework is introduced and validated,and the different superstructure optimization approaches are benchmarked.The results indicate that even though surrogate-based optimization approaches alleviate the underlying computational issues,there remains a potential issue regarding their validation.The development of appropriate surrogate models,comprising the selection of surrogate type,sampling type,and size for training and cross-validation sets,are essential factors.Regarding this aspect,satisfactory validation metrics do not ensure a successful outcome from its embedded use in an optimization problem.Furthermore,the framework’s synergistic effects by sequentially performing superstructure optimization to determine candidate process topologies and simulationbased optimization to consolidate the process design under uncertainty offer an alternative and promising approach.These findings invite for a critical assessment of surrogatebased optimization approaches and point out the necessity of benchmarking to ensure consistency and quality of optimized solutions.     

紫外/氯耦合处理饮用水中氨氮的响应面优化

基于响应面优化法,研究紫外/氯耦合处理饮用水中氨氮的效能。考察氯氮质量比、紫外辐射时间和pH值3个影响因素及其交互作用对氨氮去除的影响,采用二阶方程进行数学模拟,并优化工艺条件。结果表明,紫外/氯耦合技术能有效去除氨氮,三因素均对氨氮的去除影响显著,各因素的交互作用也显著存在。数学拟合模型的相关系数较高（R²=0.992）,模型回归性好。满足饮用水氨氮出水要求（0.5 mg·L^-1）的最优工艺条件为：氯氮质量比4.00,紫外辐射时间6.00 min和pH值7.5。验证实验结果与预测值的偏差仅为0.64%,响应面拟合方程可用于氨氮去除率的预测和最优工艺条件的确定。紫外/氯耦合技术是一种新型的氨氮去除方法,具有投药量小、去除效率高、操作简单等优点。     

Application of response surface methodology and central composite rotatable design for modeling and optimization of a multi-gravity separator for chromite concentration

In this study, the application of response surface methodology (RSM) and central composite rotatable design (CCRD) for modeling and optimization of the influence of some operating variables on the performance of a multi-gravity separator (MGS) for chromite concentration is discussed. Three MGS operating variables, namely drum speed, tilt angle, and wash water flow rate were changed during the concentration tests based on CCRD. The range of values of the MGS variables used in the design were a drum speed of 133-217 rpm, tilt angle of 1.6°-8.4°, and wash water flow rate of 1.3-4.7 lpm. A total of 20 concentration tests were conducted using MGS on chromite ore obtained from Kangal/Eskikoy—Turkey.In order to optimize chromite concentration with MGS, mathematical model equations were derived by computer simulation programming applying least squares method using MATLAB 7.1. These equations that are second-order response functions representing concentrate grade and recovery were expressed as functions of three operating parameters of MGS. Predicted values were found to be in good agreement with experimental values (R² values of 0.96 and 0.98 for concentrate grade and recovery, respectively). In order to gain a better understanding of the three variables for optimal MGS performance, the models were presented as 3-D response surface graphs. This study has shown that the RSM and CCRD could efficiently be applied for the modeling of MGS for chromite concentration and it is an economical way of obtaining the maximum amount of information in a short period of time and with the fewest number of experiments.     

星点设计-效应面优化乳化交联法制备恩诺沙星壳聚糖微球

以平均粒径、载药量、包封率及总评归一值为评价指标,运用星点设计考察芯材比、油水相比、壳聚糖浓度对微球制备的影响,对结果进行二项式拟合,效应面法选取最佳工艺条件并进行预测分析。结果显示,最佳工艺条件为：油水相比为4.2∶1,壳聚糖浓度为2%,交联时间为3.5 h。在此条件下,制得的微球粒径均一,球形圆整,平均粒径为7.21μm,包封率为61.34%,载药量为70.12%。体外释放行为符合Higuchi方程,2 h和24 h时累积释放率分别为32%和84%。     

化工过程设计的多目标不确定优化研究

In many circumstances, chemical process design can be formulated as a multi-objective optimization （MOO） problem. Examples include bi-objective optimization problems, where the economic objective is maximized and environmental impact is minimized simultaneously. Moreover, the random behavior in the process,property, market fluctuation, errors in model prediction and so on would affect the performance of a process. Therefore, it is essential to develop a MOO methodology under uncertainty. In this article, the authors propose a generic and systematic optimization methodology for chemical process design under uncertainty. It aims at identifying the optimal design from a number of candidates. The utility of this methodology is demonstrated by a case study based on the design of a condensate treatment unit in an ammonia plant.     

Optimization of Nannochloropsis oculata growth using the response surface method

Optimization of Nannochloropsis oculata growth was undertaken using the response surface method. A central composite design was defined to study the effects of temperature, pH, incident light intensity and aeration rate on the maximum growth rate of the microalga. Using statistical analysis, the first model calculated to fit results was twice improved. The final model obtained was used to clarify the effects of each factor and their interactions on the growth of Nannochloropsis oculata. The optimum growth conditions of this microorganism were also estimated as 21 °C, 52 µmol photons m^?2 s^?1, pH 8.4 and 14.7 VVH of aeration rate. These conditions were tested and validated experimentally since the maximum growth rate achieved with these parameters, 0.0359 h^?1, is the best reported in this study. Copyright © 2006 Society of Chemical Industry     

Optimization of process parameters for electrochemical nitrate removal using Box-Behnken design

Electrochemical reduction of nitrate in an undivided cell was studied in the present experiments. The optimization of the influencing factors on electrochemical reduction of nitrate by response surface methodology (RSM) was also studied. An ideal condition of performing both cathodic reduction of nitrate and anodic oxidation of the formed by-product in the presence of NaCl was achieved in the present experiment. The Box-Behnken design can be employed to develop mathematical models for predicting electrochemical nitrate removal geometry. The removal is sensitive to the current density and time in the present study. The value of R² > 0.99 for the present mathematical model indicates the high correlation between observed and predicted values. The optimal NaCl dosage, current density and electrolysis time for nitrate removal in the present experiment are 0.47 g L⁻¹, 26.06 mA cm⁻², and 111.88 min, respectively, at which the nitrate nitrogen (nitrate-N) and ammonia nitrogen (ammonia-N) concentration in the treated solution are 9.80 and 0 mg L⁻¹, respectively, which will meet the standards for drinking water.     

Composition optimization of poly(vinyl alcohol)‐/cornstarch‐blended biodegradable composite using response surface methodology

Response surface methodology was used to analyze the effect of amylase level (X₁) and glycerol level (X₂) on the objective [water solubility index (WSI), water absorption index (WAI), and Max. loading] attributes of a poly(vinyl alcohol)‐/cornstarch‐blended composite. A rotable central‐composite design (CCD) was used to develop models for the objective responses. The experiments were run at die temperature 100°C with a feed rate of 25 g/min and a screw speed of 35 rpm. Responses were most affected by changes in the amylase level (X₁) and to a lesser extent by glycerol level (X₂). Individual contour plots of the different responses were overlaid, and regions meeting the optimum WSI of 3.03 (%), WAI of 5.08 (g gel/g dry wt), and Max. loading of 29.36 (N) were identified at the amylase level of 2.8 (mL) and the glycerol level of 92.2 (mL), respectively. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

As(V) removal using a magnetic layered double hydroxide composite

The Mg–Fe–Zr layered double hydroxide/Fe₃O₄ composite was synthesized by co-precipitation of layered double hydroxide (LDH) precursors in the presence of Fe₃O₄ particles and its arsenic adsorption behavior was investigated. The material characterization by XRD, TEM, surface area analysis, SEM-EDX, and VSM revealed that the composite was comprised of Fe₃O₄ particles covered by an LDH. The As(V) adsorption capacity of the composite (188 mg/g) was achieved at pH 3. The kinetics studies and adsorption isotherms suggested a two-stepped adsorption mechanism of the monolayer adsorption inside the interlayers of LDH.     

An empirical model for kinetics of boron removal from boroncontaining wastewaters by the electrocoagulation method in a batch reactor

Boron removal from boron containing wastewaters prepared synthetically via the electrocoagulation method was studied. The experiments in which aluminum plate electrode was used were carried out in a batch reactor. The solution pH, initial boron concentration, current density, type of supporting electrolyte, temperature of solution and stirring speed were selected as experimental parameters. The obtained experimental results showed that efficiency of boron removal increased with increasing current density and decreased with increasing boron concentration in the solution. Supporting electrolyte had not significant effects on the percent of total boron removal. pH was very important parameter effecting boron removal and optimum pH was determined to be 8.0. This pH value reached an agreement with activity-pH diagrams for Al⁺³ species in equilibrium with Al(OH)₃ and boron species in aqueous media. As a result of increasing interaction between boron ions and dissolved aluminum ions in solution, the increasing solution temperature increased boron removal efficiency. Increasing stirring speed decreased boron removal efficiency where the increasing stirring speed decreased the capability of floc formation of aluminum ions. As a result, it was seen that about 99% of boron in the wastewater could be removed at optimum conditions. In addition, the process kinetics was predicted by using heterogeneous fluid–solid reaction models. It was seen statistically that the kinetics of this process agreed with the pseudo-second-order model as follows: X_B/(l−X_B) = 18,241[OH][C]^−3.45[CD]^7.79[t]^1.41[S]^−3.65exp[−30,668/RT].     

大团囊虫草L2分离鉴定及其发酵工艺优化

A strain isolated from the fruiting body of a fungus parasitized on Elaphomyces was identified as Cordyceps ophioglossoides based on the morphological characteristics and the analysis of ITS-5.8s rDNA sequence. The optimal medium composition (g•L－1), containing sucrose 66.0, yeast powder 10.0, silkworm chrysalises digest 30.0, MgSO4•7H2O 0.4, and KH2PO4 0.4, was found using fractional factorial design and a central composite design, and the optimization of cultural conditions obtained a result of seed age 6 days, inoculum size 6% (by volume), initial pH 5.6, temperature 24°C, shaking speed 160 r•min－1 by one-factor-at-a-time method. The maximum biomass reached about 20.2 g•L－1 after 90 hours culture under the optimal conditions. Elementary pharmacological activities showed that mycelia of C. ophioglossoides L2 from submerged culture promoted uterus growth in estrogen- depleted mice. In the 15-litre scale-up fermentation, the mycelial biomass was around 19.1 g•L－1, indicating a promising prospect for this biotechnology and the potency to develop its medical value.