Optimization of biodiesel production process in a continuous microchannel using response surface methodology

We assessed the biodiesel production process in a continuous microchannel through preparation of a heterogeneous catalyst (CaO/MgO) from demineralized water plant sediment. This mixed oxide catalyst was used for transesterification of rapeseed oil as feedstock by methanol to produce biodiesel fuel at various conditions. A microchannel, utilized as a novel reactor, was applied to convert rapeseed oil into biodiesel in multiple steps. The effects of the process variables, such as catalyst concentration, methanol to oil volume ratio, n-hexane to oil volume ratio, and reaction temperature on the purity of biodiesel, were carefully investigated. Box-Behnken experimental design was employed to obtain the maximum purity of biodiesel response surface methodology. The optimum condition for the production of biodiesel was the following: catalyst concentration of 7.875 wt%, methanol to oil volume ratio of 1.75: 3, n-hexane to oil volume ratio of 0.575: 1, and reaction temperature of 70 °C.     

Optimisation of a fermentation process for butanol production by particle swarm optimisation (PSO)

BACKGROUND: The performance of three particle swarm optimisation (PSO) algorithms was assessed in relation to their capability to optimise an alternative fermentation process for the production of biobutanol. The process consists of three interconnected units: fermentor, cell retention system and vacuum flash vessel (responsible for the continuous recovery of butanol from the broth). The dynamic behaviour of the process was described by a non‐linear mathematical model. Four constrained optimisation problems were formulated concerning the operation and design of flash fermentation: (1) maximisation of butanol productivity; (2) maximisation of substrate conversion; (3) and (4) adjustment of operating conditions in the face of problems of fluctuations in the quality of the agricultural raw material and changes in the kinetics of the microorganisms. RESULTS: The design and operation of the flash fermentation process based on the optimisation of productivity, instead of substrate conversion, resulted in a smaller fermentor and provided satisfactory values of operating conditions able to overcome problems of variations in the glucose concentration in the raw material and changes in kinetics. CONCLUSIONS: The differences among the PSO algorithms, i.e. the velocity equation and parameters values, had significant effects on the optimisation, the best results being obtained with the original velocity equation with the inertia weight decreasing linearly with each iteration. The PSO algorithms obtained solutions that obeyed constraints, demonstrating that a constraint handling method originally developed for genetic algorithms can be applied successfully to PSO algorithms. Copyright © 2010 Society of Chemical Industry     

响应面法优化以重组大肠杆菌发酵生产类人胶原蛋白过程

In order to improve the production of human-like collagen Ⅲ (HLC Ⅲ) by fed-batch culture of recom-binant Escherichia coli BL21, the Plackett-Burman and Box-Behnken design were applied to optimize the fermen-tation process parameters.Three variables (induction time, inoculum age and pH), which have significant effects on HLC Ⅲ production, were selected from eight variables by Plackett-Burman design.With the regression coefficient analysis in the Box-Behnken design, a relationship between HLC Ⅲ production and three significant factors was obtained, and the optimum levels of the three variables were as follows: induction time 3.2h, inoculum age 12.6 h and pH 6.7.The 3D response surface plots and 2D contour plots created by the Box-Behnken design showed that the interaction between induction time and pH and that between innoculum age and pH were significant.An aver-age 9.68 g·L~(-1)HLC Ⅲ production was attained in the validation experiment under optimized condition, which was 80% higher than the yield of 5.36 g·L~(-1) before optimization.     

Process optimization design for jatropha-based biodiesel production using response surface methodology

Biodiesel of non food vegetal oil origin is gaining attention as a replacement for current fossil fuels as its non-food chain interfering manufacturing processes shall prevent food source competition which is expected to happen with current biodiesel production processes. As a result, non edible Jatropha curcas plant oil is claimed to be a highly potential feedstock for non-food origin biodiesel. CaO–MgO mixed oxide catalyst was employed in transesterification of non-edible J. curcas plant oil in biodiesel production. Response surface methodology (RSM) in conjunction with the central composite design (CCD) was employed to statistically evaluate and optimize the biodiesel production process. It was found that the production of biodiesel achieved an optimum level of 93.55% biodiesel yield at the following reaction conditions: 1) Methanol/oil molar ratio: 38.67, 2) Reaction time: 3.44 h, 3) Catalyst amount: 3.70 wt.%, and 4) Reaction temperature: 115.87 °C. In economic point of view, transesterification of J. curcas plant oil using CaO–MgO mixed oxide catalyst requires less energy which contributed to high production cost in biodiesel production. The incredibly high biodiesel yield of 93.55% was proved to be the synergetic effect of basicity between the active components of CaO–MgO shown in the physicochemical analysis.     

Optimisation of reaction conditions for the synthesis of single‐walled carbon nanotubes using response surface methodology

The effects of three preparation variables, i.e. reaction temperature, reaction time and reaction gas (methane/nitrogen) flow rate, on the ratio of the intensity of the Raman D band to the intensity of the G band (I_D/I_G), carbon mass and the presence of radial breathing mode (RBM) peaks were investigated by using a central composite design to develop two linear models. The most influential factor in each experimental design‐response was identified using the analysis of variance. The predicted I_D/I_G ratio, carbon mass and presence of RBM peaks determined during the process optimisation were found to agree satisfactorily with the experimental values. The optimum conditions for synthesising single‐walled carbon nanotubes were determined to be a reaction temperature of 900°C, a reaction time of 59 min and a reaction gas flow rate of 54 mL/min. © 2011 Canadian Society for Chemical Engineering     

响应面法优化壳聚糖酶产生菌Mitsuaria sp.K1的产酶发酵条件

壳聚糖（chitosan）及其降解产物因具有优良的物理特性和生物活性而被广泛关注。通过平板透明圈初筛、摇瓶复筛方法,从青岛海岸土壤中分离筛选到1株产壳聚糖酶活性较高的细菌Mitsuaria sp.K1,并对其产酶发酵条件进行了单因素试验和响应面优化分析试验。结果表明：在最适培养基组成（1%粉末壳聚糖、0.5%硝酸钾、0.22%KH2PO4、0.1%Na2HPO4、0.15%KCl、0.05%MgSO4?7H2O）和最佳培养条件（培养温度25.2 ℃,培养时间25.4 h,起始pH值6.5,接种量3%,装液量100 mL/500 mL摇瓶,160 r/min）下,Mitsuaria sp.K1的发酵粗酶液最高酶活平均达11.56 U/mL,比优化前的2.17 U/mL提高了4.32倍。与前人研究结果相比,该菌发酵产酶温度降低了5～10 ℃,产酶周期缩短了23～47 h,因此具有工业发酵应用价值。     

响应面法优化甘露醇产丁醇的发酵条件

以褐藻的主要成分甘露醇为底物,利用丙酮丁醇梭菌ATCC824发酵生产丁醇。采用Plackett-Burman（P-B）和Box-Behnken优化发酵条件。在Plackett-Burman实验设计时,考察牛肉膏、酵母浸粉、胰蛋白胨、乙酸铵、 KH2PO4、MgSO4?7H2O、FeSO4?7H2O、接种量、发酵温度、初始pH值这10个因素对丁醇产量影响,筛选出影响丁醇发酵的重要参数是发酵温度、初始pH值、乙酸铵浓度,利用Box-Behnken设计确定最优发酵条件为发酵温度37.3 ℃、初始pH值6.38、乙酸铵浓度2.82 g/L。数学模型分析预测最大丁醇产量为8.47 g/L。经实验验证表明,在优化条件下的丁醇产量平均值达到8.52±0.55 g/L。这说明利用统计学方法优化甘露醇的丁醇发酵条件是有效的。     

Process optimization of oxidative coupling of methane for ethylene production using response surface methodology

The statistical design of experiments (DoE) was used in the process study of oxidative coupling of methane (OCM) over Na? W? Mn/SiO₂ catalyst. A set of factors with a certain range was screened using factorial design with respect to three responses: methane conversion, C₂₊ products selectivity and ethylene/ethane ratio. The variances were analyzed and the interaction effects of the process parameters were evaluated. With the understanding of the process, the optimization of the process was further studied using response surface methodology coupled with central composite design (CCD). The optimum conditions were obtained as reaction temperature = 850 °C, gas hourly space velocity = 23 947 cm³ g^?1 h^?1, catalyst pretreatment period = 2 h, dilution ratio = 0.2 and CH₄/O₂ ratio = 7. 40.55% of methane conversion and 79.51% of C₂₊ product selectivity were obtained under these optimum conditions. Experimental runs under optimum conditions were repeated and compared with the simulated values obtained from the model. There was good agreement between the experimental and simulated values. Copyright © 2007 Society of Chemical Industry     

响应面法优化纳豆激酶液态发酵条件

目的响应面法优化纳豆激酶液态发酵条件。方法以纳豆芽孢杆菌(Bacillus subtilis Natto)为出发菌株,液态发酵纳豆激酶。在单因素试验确定接种量、温度、初始pH及发酵时间对纳豆激酶活力产生影响的基础上,采用BoxBehnken软件进行响应面优化。结果最终确定纳豆激酶液态发酵的最佳条件为:接种量3%,温度40℃,pH 7.0,发酵时间84 h。在该条件下液态发酵生产纳豆激酶的活力可达749.41 U/ml,与模型预测的酶活力(752.35 U/ml)的相对误差为0.39%。结论成功优化了纳豆激酶液态发酵条件,为纳豆激酶的产业化生产奠定了基础。     

响应面优化高盐稀态酱油发酵工艺

以麸皮、面粉为原料进行高盐稀态发酵,在单因素试验基础上,以氨态氮含量为响应值,对高盐稀态发酵工艺条件进行响应面优化。确定最佳工艺条件为:发酵温度41℃,发酵时间91d,盐水浓度14%。在此条件下,氨态氮含量为1.21 g/mL。     

响应面法优化达托霉素发酵培养基

采用响应面法对玫瑰孢链霉菌发酵产达托霉素的培养基进行了优化。首先通过Placket-Burman设计法筛选出影响达托霉素产量的4个重要因素:初始pH值、葡萄糖、L-天冬氨酸(L-Asp)、硫酸钾。其中初始pH值的影响极为显著(p<0.01),因此,对初始pH值进行了单因素试验,得到最优初始pH值为8.6。在此基础上对其余3个因素用最陡爬坡路径逼近最大响应区域后,利用响应面中心组合设计对显著因素进行优化,得到最适培养基组成为:葡萄糖13.0 g/L、L-Asp 2.6 g/L、硫酸钾4.1 g/L。在此优化条件下,达托霉素产量达373.98 mg/L,与预测值(365.76 mg/L)非常接近,比优化前产量提高了2.25倍。     

Optimization of critical medium components using response surface methodology for lipase production by Rhizopus delemar

The production process of a 1,3-position specific lipase from Rhizopus delemar was optimized by response surface methodology (RSM) and a Box–Behnken experimental design was used to study the interactive effects of fermentation medium components on lipase activity and microorganism growth. Preliminary batch tests were employed to obtain the favorable conditions for lipase activity analysis and found that sucrose, molasses, yeast extract, sunflower oil, tween-80 have significant influences on the lipase production and microorganism growth. The concentrations of five fermentation medium components were optimized. Among five variables, molasses sucrose and yeast extract were identified as less significant variables for lipase production. The optimum fermentation medium composition for lipase production by R. delemar was sucrose concentration 4.19 g/L, molasses sucrose 1.32 g/L, yeast extract 0.53 g/L, sunflower oil 1.11% (v/v), and tween-80 1.80% (v/v). In these conditions, the biomass concentration of 4.52 g/L with a lipolytic activity of 1585 μmol/L min was reached.     

Statistical optimization of process parameters for the production of vanillic acid by solid‐state fermentation of groundnut shell waste using response surface methodology

BACKGROUND: Vanillic acid is a flavoring agent and also serves as precursor for vanillin production. Culture medium and fermentation condition for the single step production of vanillic acid from Phanerochaete chrysosporium using lignocellulosic waste as a substrate under solid state fermentation (SSF) were optimized using response surface methodology. RESULTS: The process parameters were chosen by borrowing methodology, and L‐asparagine, pH and moisture content of the solid medium during SSF were identified as the most significant variables. The optimum value of selected variable and their mutual interactions were determined by response surface methodology. The result demonstrated that a yield of 73.58 mg vanillic acid g^?1 substate was predicted under optimum conditions (L‐asparagine 5.98 mmol L^?1 (2.37 mg g^?1 groundnut shell), pH of solid medium 4.51 and moisture content 74.83%). The predicted response was experimentally validated and resulted in a maximum vanillic acid yield of 73.69 mg g^?1 after 8 days of SSF. CONCLUSION: The optimization of fermentation variables resulted in a maximum 10‐fold increase in vanillic acid yield compared with that observed under sub‐optimal conditions (from 7.2 mg g^?1 to 73.69 mg g^?1). Copyright © 2011 Society of Chemical Industry     

Optimization of antioxidant hydrolysate production from flying squid muscle protein using response surface methodology

The squid muscle protein, extracted from by-products of flying squid (Ommastrephes bartrami) was hydrolyzed by five proteases (pepsin, trypsin, papain, alcalase and flavourzyme). DPPH radical scavenging power was used to evaluate antioxidative activity of hydrolysates. The hydrolysate obtained by papain exhibited the most excellent potential of antioxidative activity. Furthermore, response surface methodology (RSM) was employed to optimize hydrolysis conditions, including enzyme to substrate (E/S) ratio, reaction temperature, and hydrolysis time. The optimum conditions obtained were as follows: E/S ratio of 1.74%, temperature of 51 °C and time of 46 min, under which, DPPH radical scavenging activity of 74.25% was obtained. Moreover, it was found that the optimum hydrolysate of 8 mg/mL displayed relatively stronger inhibitory effect on lipid peroxidation compared with α-Tocopherol of 0.1 mg/mL.     

Preparation of granular activated carbon from oil palm shell by microwave-induced chemical activation: Optimisation using surface response methodology

In this study, waste palm shell was used to produce activated carbon (AC) using microwave radiation and zinc chloride as a chemical agent. The operating parameters of the preparation process were optimised by a combination of response surface methodology (RSM) and central composite design (CCD). The influence of the four major parameters, namely, microwave power, activation time, chemical impregnation ratio and particle size, on methylene blue (MB) adsorption capacity and AC yield were investigated. Based on the analysis of variance, microwave power and microwave radiation time were identified as the most influential factors for AC yield and MB adsorption capacity, respectively. The optimum preparation conditions are a microwave power of 1200 W, an activation time of 15 min, a ZnCl₂ impregnation ratio of 1.65 (g Zn/g precursor) and a particle size of 2 mm. The prepared AC under the optimised condition had a BET surface area (S_BET) of 1253.5 m²/g with a total pore volume (V_tot) of 0.83 cm³/g, which 56% of it was contributed to the micropore volume (V_mic).     

Electrochemical treatment of bisphenol-A using response surface methodology

The decomposition of bisphenol-A (BPA) in synthetic solution and in municipal effluent was investigated using an electro-oxidation process. Electrolysis was conducted using a cylindrical electrolytic cell containing two circular anodes (expanded metal) and two circular cathodes (stainless steel) alternated in the electrode pack. Different anode materials (Ti/SnO₂, Ti/IrO₂ and Ti/PbO₂) were tested, and Ti/PbO₂ was found to be the most effective electrode for BPA degradation. An experimental design methodology (2³ Box–Behnken design) was applied to determine the optimal experimental conditions in terms of cost effectiveness. The BPA concentration (C ₀ = 1.0 mg l⁻¹) could be optimally diminished by up to 90% by applying a current intensity of 2.0 A for a 100-min reaction period in the presence of 250 mg Na₂SO₄ l⁻¹ (used as a supporting electrolyte). Then, the optimal conditions were applied on a municipal wastewater effluent (sampled after secondary treatment) artificially contaminated with 1 mg BPA l⁻¹ without the addition of a supporting electrolyte. The treatment was more effective with the municipal effluent due to the presence of a high concentration of chloride ions that could easily be transformed into active chlorine. BPA could be oxidized by both direct anodic electrochemical oxidation (by means of OH·) and indirect electrochemical oxidation via mediators, such as hypochlorous acid generated by chloride oxidation. Both actions (direct and indirect effects) lead to the formation of powerful oxidizing agents capable of rapidly oxidizing BPA.     

响应面法优化丙酮缩甘油合成工艺的研究

以甘油和丙酮为原料,对甲苯磺酸催化合成丙酮缩甘油。以响应面法优化合成工艺,考察物料比(甘油/丙酮)、反应时间、催化剂用量对丙酮缩甘油的得率的影响。结果表明,最佳合成条件为:物料比(甘油∶丙酮)为1∶5(摩尔比),催化剂用量为甘油用量的5%,反应时间5.5 h。在该工艺条件下,缩甘油的得率为90.52%。