Modeling and Optimization of Catalytic Dehydration of Ethanol to Ethylene Using Central Composite Design

The central composite design in the modeling and optimization of catalytic dehydration of ethanol to ethylene was performed to improve the ethylene yield.A total of 20 experiments at random were conducted to investigate the effect of reaction temperature,Si/Al ratios of H-ZSM-5 catalyst and liquid hourly space velocity(LHSV) on the ethylene yield.The results show that the relationship between ethylene yield and the three significant independent variables can be approximated by a nonlinear polynomial model,with R-squared of 99.9%and adjusted R-squared of 99.8%.The maximal response for ethylene yield is 93.4%under the optimal condition of 328 ℃,Si/Al ratio 85,and LHSV 3.8 h-1.

Optimization Studies in Simultaneous Saccharification and Fermentation of Wheat Bran Flour into Ethanol

The effects of process variables in Simultaneous Saccharification and Fermentation (SSF) of wheat bran flour were studied in bulk fermentation using a coculture of Aspergillus niger - Kluveromyces marxianus. The effect of substrate density, pH, temperature, and enzyme concentration on wheat bran was predicted by designing experiments in which a single parameter is varied keeping other variables at a constant level. The above parameters were optimized for a batch culture in a fermentor. Optimal values for substrate concentration, pH, temperature, and enzyme concentration during processing were 200 g/l, 5.5, 65°C, and 7.5 IU, respectively. In pre-treatment experiments, the concentration of enzymes and the pre-treatment temperature are highly correlated. The influence of pH, temperature, and substrate density on ethanol production was investigated. Temperature pH was determined as optimal, 32°C and 5.5, respectively. After 48 hours of fermentation at optimum pH, a solution of wheat bran containing a maximum of 6% starch produces a maximum of 22.9 g/l ethanol.

Energy, Environment, Economic Life Cycle Assessment of Cassava-based Ethanol Used as Automotive Fuel in Guangxi Province, China

A life-cycle assessment (LCA) was carried out to compare the energy, environmental and economic impacts of converting cassava to fuel ethanol in Guangxi Province, China. The entire life cycle is a system that includes stages from cassava farming to ethanol fuel combustion. A computer-based model was developed to assess energy, environmental, and economic (EEE) life cycle implication of cassava-based ethanol fuel. The LCA results for fuel ethanol were compared to conventional gasoline (CG) as a base-line case. On the life-cycle bases, the use of cassava-based ethanol fuel in Guangxi may consume more energy but reduce greenhouse gas, VOC, and CO emissions. Life cycle cost results indicate that although fuel ethanol currently is not competitive compared to conventional gasoline, it has great potentials when there are subsidies and/or yields of cassava planting are improved. In terms of balancing the energy, environmental and economical, the introduction form of cassava-based ethanol fuel would be E10. The assessment results generated from this study provide an important reference for Guangxi policy makers to better understand the trade-offs among energy, environmental effects, and economics for the most effective using of regional energy resources.

Optimization of conditions for supercritical fluid extraction of flavonoids from hops (Humulus lupulus L.)

Waste hops are good sources of flavonoids. Extraction of flavonoids from waste hops (SC-CO2 extracted hops) using supercritical fluids technology was investigated. Various temperatures, pressures and concentrations of ethanol (modifier) and the ratio (w/w) of solvent to material were tested in this study. The results of single factor and orthogonal experiments showed that at 50 °C, 25 MPa, the ratio of solvent to material (50%), ethanol concentration (80%) resulted in maximum extraction yield fla- vonoids (7.8 mg/g). HPLC-MS analysis of the extracts indicated that flavonoids obtained were xanthohumol, the principal prenylflavonoid in hops.

Enzymatic Hydrolysis and Fermentation of Plantain Peels: Optimization and Kinetic Studies

The aim of this work was to optimize the hydrolysis and fermentation of plantain peels. Kinetic study was also carried out. Proximate analysis of plantain peels was carried out and the result showed that it contains 46% cellulose. Aspergillus niger isolated and screened for cellulase activities was used as the crude enzyme for the hydrolysis and commercial availableSaccharomyces cerevisae was used for the fermentation. The optimization was done using quadratic model of central composite rotatable design for both hydrolysis and fermentation. Analysis of variance ANOVA was used to test for the significance of the model and the factors. The results of the analysis showed that temperature, time, pH and the substrate concentration significantly affected the yield of simple sugar in the hydrolysis of plantain peels. The result equally showed that temperature, time and pH were significant factors of fermentation. The optimum conditions for the hydrolysis were 35°C, 5 days, and pH of 5.5, substrate concentration of 8 g/30ml and glucose yield of 49%. Also the optimum conditions of fermentation were obtained as 30°C, pH of 4.0, 9 days and ethanol yield of 19%. The Michaelis-Menten model adequately fit both the hydrolysis and fermentation kinetics.

Fuel ethanol production using novel carbon sources and fermentation medium optimization with response surface methodology

In this study,ethanol production abilities of the novel carbon sources:sodium and calcium gluconate in different minimal and rich media were compared with glucose using Escherichia coli KO11.The strain produced higher ethanol yield in the rich medium Luria-Bertani(LB)than the other two minimal media:corn steep liquor(CSL)and M9 for two substrates(sodium and calcium gluconate).Additionally,higher ethanol yields were achieved when the strain was grown in LB and M9 medium with calcium gluconate than sodium gluconate,while the ethanol yields were similar when both sodium and calcium gluconate were added into CSL medium respectively.Response surface methodology was used to optimize the fermentation medium components for enhancing ethanol production using strain E.coli KO11 in CSL medium with calcium gluconate as the substrate in batch culture.The concentration of the potassium phosphate buffer is the only significant factor among five factors considered.A quadratic model was developed to describe the relationship between ethanol production and the factors.The optimal conditions predicted for five factors were 14.38 g/L CSL,0.0398 g/L FeCl_(3)·6H2O,1.12 g/L MgSO_(4)·6H_(2)O,15.41 g/L(NH4)_(2)SO_(4),and 1.58/1.26 g/L KH_(2)PO_(4)/K_(2)HPO_(4)(2:1 molar ratio).The highest ethanol concentration under optimal conditions was 31.5 g/L,which was 5.6 g/L higher than that from the same fermentation concentration of calcium gluconate in LB media.The high correlation between the predicted and experimental values confirmed the validity of the model.

Optimization and kinetic studies for enzymatic hydrolysis and fermentation of colocynthis vulgaris Shrad seeds shell for bioethanol production

The key process parameters for the hydrolysis and fermentation of Colocynthis vulgaris Shrad seeds shell(CVSSS)were optimized using the Box-Behnken Design(BBD)of Response Surface Methodology(RSM).Kinetic study was also carried out.The proximate analysis of the CVSSS was done by the method of the Association of Organic and Applied Chemistry(AOAC).Enzymatic hydrolysis was experimented by using Aspergillus Niger as a crude enzyme isolated from soil at sawdust dump site and screened for cellulosic activities.Factors that affected the hydrolysis of the CVSSS were screened by using the Greco-Latin square design of experiment.However,for Saccharomyces cerevisiae,factors that affected the fermentation of the CVSSS were screened by using the same Greco-Latin square design of experiment.Meanwhile,the result of the proximate analysis revealed that the CVSSS had 73.54%cellulose which could be converted to bioethanol.It was established that temperature,pH and time had significant effect on hydrolysis,while the optimum results were obtained at 46.8℃,3.32 d,5.68 and 59.87%for temperature,time,pH and glucose yield,respectively.Temperature,yeast dosage,pH and time had significant effect on fermentation,while the optimum results from optimization were found to be 33.58℃,7.0,3.55 d,1.65 g per 50 mL and 25.6%for temperature,pH,time,yeast dosage and ethanol yield,respectively.The kinetics of both the enzymatic hydrolysis and fermentation agreed with the Michealis-Menten kinetic model with the correlation coefficients(R^(2))of 0.9708 and 0.8773,respectively.However,from the error analysis,the experimental and predicted values had a very good relationship as described by Michaelis-Menten model.

Ethanol mediated As(Ⅲ) adsorption onto Zn-loaded pinecone biochar：Experimental investigation,modeling,and optimization using hybrid artificial neural network-genetic algorithm approach

Organic matters（OMs） and their oxidization products often influence the fate and transport of heavy metals in the subsurface aqueous systems through interaction with the mineral surfaces. This study investigates the ethanol（EtO H）-mediated As（Ⅲ） adsorption onto Zn-loaded pinecone（PC） biochar through batch experiments conducted under Box–Behnken design. The effect of EtO H on As（Ⅲ） adsorption mechanism was quantitatively elucidated by fitting the experimental data using artificial neural network and quadratic modeling approaches. The quadratic model could describe the limiting nature of EtO H and pH on As（Ⅲ） adsorption,whereas neural network revealed the stronger influence of Et OH（64.5%） followed by pH（20.75%）and As（Ⅲ） concentration（14.75%） on the adsorption phenomena. Besides, the interaction among process variables indicated that Et OH enhances As（Ⅲ） adsorption over a pH range of2 to 7, possibly due to facilitation of ligand–metal（Zn） binding complexation mechanism.Eventually, hybrid response surface model–genetic algorithm（RSM–GA） approach predicted a better optimal solution than RSM, i.e., the adsorptive removal of As（Ⅲ）（10.47 μg/g） is facilitated at 30.22 mg C/L of Et OH with initial As（Ⅲ） concentration of 196.77 μg/L at pH 5.8. The implication of this investigation might help in understanding the application of biochar for removal of various As（Ⅲ） species in the presence of OM.

Optimization of sugar production from Durian seeds via alkaline hydrolysis for second-generation bioethanol production

As one way to eliminate the issues found in the preceding generation,feedstock exploration in second-generation bioethanol production remains an issue,especially for a tropical country such as Indonesia.From exotic fruit by-products,durian holds a promising perspective that rests on its abundance,superb carbohydrate content and limited usage until now.This work presents the first-ever utilization of durian seeds for sugar production under optimized conditions through alkaline hydrolysis.A simple form of sugar was extracted by varying four parameters,namely substrate loading,NaOH concentration,hydrolysis time and hydrolysis temperature.Response surface methodology based on the Box-Behnken design was employed to outline the most optimum parameter values.Analysis of variance revealed that the quadratic model fit the data appropriately with the order of significance as substrate loading>hydrolysis time>NaOH concentration>hydrolysis temperature.The optimized conditions for reducing sugar yield,as high as 2.140 g/L,corresponded to<50 g/L substrate loading,0.522 M NaOH,60 minutes of hydrolysis time and 80oC hydrolysis temperature.The possible ethanol content of 1.094 g/L was also expected under optimized conditions,demonstrating great potential in second-generation bioethanol production.

Energy-Efficient Production of Cassava-Based Bio-Ethanol

Fuel ethanol is an important renewable and sustainable fuel, produced in China by fermentation of mostly corn, wheat and cassava feedstock. Fermentation produces an ethanol-lean broth (10 to 12 vol%). Ethanol is recovered by distillation, followed by a molecular sieve drying beyond the azeo-tropic point. The distillation and molecular sieve operations consume most of the total energy used, with the steam consumption currently being ~1.8 kg/kg ethanol, including 0.5 kg/kg ethanol in the final molecular sieve stage during regeneration. The objectives of the paper are fourfold: 1) firstly to study the distillation process of a large-scale cassava-based fuel ethanol production (200,000 tons per year), by field measurements and by using an Aspen Plus V8.2 simulation, with and without energy integration of condensers and reboilers, resulting in a distillation steam consumption of ~1.3 kg/kg ethanol;2) secondly, to examine the effects of using Very High Gravity (VHG) fer-mentation of cassava meal mash. By using VHG fermentation, the ethanol concentration in the fermenter broth is significantly increased, to about 19 vol% (15.4 wt%). The steam consumption is then reduced to ~0.94 kg/kg, representing a considerable saving in comparison with the current operation. Applying VHG fermentation needs minor additional investment, rapidly recovered through the energy savings and the smaller size of equipment;3) thirdly, to assess the application of a hybrid operation, where pervaporation will be used to selectively and continuously remove ethanol from the fermenter broth, thus slightly increasing the fermentation yield by reducing the risk of ethanol inhibition, whilst producing an ehtanol-rich permeate (about 30 wt%);and finally 4) to demonstrate that the production cost of cassava-based ethanol can substantially be reduced by applying the proposed improvements.

田菁纳豆多酚提取工艺优化及其抗氧化活性

以田菁纳豆为原料,采用乙醇溶剂浸提田菁纳豆中的多酚,以田菁纳豆多酚提取量为评价指标,通过响应面试验设计优化提取工艺,并考察田菁纳豆多酚的体外抗氧化能力。经过优化得到4个因素的最佳参数为乙醇浓度30%、提取时间80 min、提取温度61℃、料液比1∶15(g/mL),该条件下田菁纳豆的实际多酚提取量为119.24 mg/g。抗氧化试验结果表明,田菁纳豆多酚对ABTS^(+)自由基、DPPH自由基、羟自由基都具有较好的清除能力,在最佳提取条件下,其最高清除率分别是53.47%、83.70%、62.18%,且对铁离子的最大还原力为3.12,表明田菁纳豆多酚具有较好的抗氧化活性。

小麦B淀粉一步酶解产糖优化及酒精发酵

以小麦B淀粉为原料,优化其一步酶解制备可发酵糖的工艺及后续酿酒酵母发酵生产酒精,提高其利用价值。首先对小麦B淀粉基本组分含量进行测定,其次使用α-淀粉酶和糖化酶组成复合酶对小麦B淀粉进行一步酶解制备可发酵糖,详细考察复合酶用量、料液比、酶解温度、酶解时间及pH对还原糖得率影响,对以上参数进行正交优化,获得酶解最佳工艺条件,最后利用酿酒酵母发酵所得酶解糖液生产酒精。结果表明,小麦B淀粉中淀粉含量85.61%,蛋白质和灰分含量都达到2%左右,戊聚糖含量接近5%,通过正交优化确定酶解产糖最佳条件为复合酶用量4 mL,料液比1:25 g/mL,酶解温度60℃,酶解时间10 h,pH5.0,在此条件下还原糖得率达到94.6%。利用酵母发酵产酒精,最终酒精浓度达到12.76 g/L,酒精原料得率为31.90%。本研究为小麦B淀粉制备酒精工艺提供参考。

超声辅助酸性乙醇法制备高纯度魔芋葡甘聚糖的工艺优化及其理化分析

采用超声辅助酸性乙醇沉淀法制备高纯度白魔芋葡甘聚糖(Konjac Glucomannan,KGM),以白魔芋KGM纯度为评价指标,通过单因素和响应面优化制备高纯度白魔芋KGM的最佳工艺条件,并分析其理化性质和结构。结果表明,超声辅助酸性乙醇法制备KGM的最佳条件为:超声时间28 min、溶剂pH值为3.7、70%体积分数的乙醇、料液比1:75、超声温度为60℃,在此条件下进行的验证试验KGM纯度为97.08%,与常规超声辅助乙醇提取法相比有较大提高。与白魔芋原粉相比,KGM的持水力(51.39 g/g)、膨胀力(17.05 mL/g)、黏度(34600 mPa·s)、阳离子交换能力和色度均得到提高,持油力(2.69 g/g)约为原粉的1.5倍。与95 wt.%KGM标品相比,以上理化性质无显著差异。微观结构显示,KGM表面杂质少,有大量类似蜂窝状的细小孔隙结构;傅里叶红外谱图显示KGM分子结构中具有多糖的特征吸收峰;热重分析表明,试验制备的样品纯度高,热稳定性好。此法制备的KGM具有较好的理化功能特性,研究结果可为高纯度魔芋葡甘聚糖的深入开发应用提供参考。

超声辅助有机酸预处理玉米芯制取生物乙醇的工艺优化

【目的】探明超声辅助有机酸预处理玉米芯的最佳工艺,为玉米芯高效制取生物乙醇提供参考。【方法】通过单因素试验(柠檬酸浓度、液料比、超声功率、超声温度和超声处理时间)与响应面试验,优化有机酸预处理玉米芯工艺,以酶解效率和乙醇产率为评价指标确定最佳酶用量和发酵方式。【结果】使用浓度为5%的柠檬酸与玉米芯粉末以液料比20∶1(mL/g)混合均匀,于75℃、360 W功率条件下超声处理33 min,玉米芯还原糖得率可达36.71%;此条件下,添加纤维素酶30 FPU/g,采用半同步法发酵72 h,玉米芯乙醇产率可达70.32%;采用分步发酵和同步发酵的最高乙醇产率分别为70.08%和70.19%。【结论】超声辅助有机酸预处理玉米芯效果好,可行性高,选择不同的发酵方式时乙醇产率无明显差异。

酿酒酵母筛选及乙醇发酵条件的优化

能源危机导致人们将视野转移到可再生能源的开发与利用上,乙醇作为一种不含硫及灰分的清洁燃料,逐渐进入人们的视野并被用于替代汽油和柴油。人们对乙醇生产方式的研究越来越多,目前生产乙醇的重要手段是通过发酵技术,利用酵母对粮食或纤维类废弃物进行发酵,将其转化为生产燃料乙醇。近年来,国内鲜有对酿酒酵母菌株筛选并优化发酵条件的研究,该研究针对天津科技大学诱变的编号为H1~H17的17株酿酒酵母进行筛选,并对筛选出的4株优良酿酒酵母进行单因素试验和正交试验,获得最优发酵条件:YPD液体培养基初始还原糖浓度为220 g/L,接菌量为1×10^(8) CFU/mL,不添加葡萄糖和添加6%的乙醇,在此条件下,发酵结束后残留还原糖含量最低,乙醇生成率最高。

南瓜中β-胡萝卜素提取工艺优化及稳定性研究

以南瓜粉为原料,探究了超声辅助乙醇法提取β-胡萝卜素的最佳工艺条件,以单因素试验为基础,进行正交试验考察各影响因素,同时探究所提取β-胡萝卜素的稳定性,包括光照、温度、pH和金属离子的影响。结果表明,南瓜中β-胡萝卜素最佳提取参数为超声时间80 min、超声温度50℃、料液比1∶8(g/mL),在此参数下,β-胡萝卜素提取量为(23.811±0.589)mg/g。在稳定性方面,光照会加速β-胡萝卜素降解,使其保留率加速下降;在100℃时保留率下降较快;在酸性(pH 4)和碱性(pH 8,10)条件下,保留率都有所降低;Na^(+)、K^(+)、Mg^(2+)、Ca^(2+)、Fe^(2+)、Zn^(2+)、Al^(3+)对其具有减色作用,Fe^(3+)具有增色作用。该研究为南瓜色素在调味品中的应用提供了理论参考。

基于离子液体的乙腈-乙醇-水共沸体系节能分离

乙腈生产过程中产生的乙腈-乙醇-水物系,由于在常压下产生了3种二元共沸物和1种三元共沸物,采取常规精馏无法对物系进行有效分离,因此基于COSMO-SAC理论对具有应用潜力的4种离子液体进行筛选,选定1,3-二甲基咪唑磷酸二甲酯([DMIM][DMP])作为分离乙腈-乙醇-水物系的适宜萃取剂,并利用σ-谱图对离子液体与该物系的作用机理进行分析;采用Aspen Plus软件建立了基于离子液体分离乙腈-乙醇-水物系的萃取精馏流程。以年度总费用(TAC)最低为优化目标,并将CO_(2)排放成本计入目标函数中进行流程优化。在此基础上,为了更有效节能,进一步设计优化了热泵精馏萃取分离流程。最终热泵精馏流程TAC比常规流程降低16.82%,CO_(2)排放费用减少了23.35%。

直接冻黄G的绿色制备工艺研究

以4,4'-二氨基二苯乙烯-2,2'-二磺酸(DSD酸)为起始原料依次与NaNO_(2)、苯酚和氯乙烷反应,分别经重氮化、偶合、醚化反应,经过滤、烘干、粉碎得直接冻黄G。重氮化、偶合、醚化反应均采用乙醇为反应溶剂,反应后乙醇回收、重复利用,避免采用大量水为反应溶剂产生大量的高盐废水,从源头上解决了大量工业高盐废水产生的问题,实现了直接冻黄G的绿色制备工艺。

构树根皮活性成分乙醇提取工艺优化及其抗氧化活性分析

以构树根皮为原料,通过单因素实验考察不同因素对构树根皮总黄酮和多酚提取量的影响。运用Design-Expert 11软件设计响应面法优化构树根皮乙醇回流提取工艺,并进行工艺验证。最后对提取得到的构树根皮乙醇提取物进行DPPH·、ABTS^(+)·、羟自由基清除能力和总还原能力的测定,评价其抗氧化活性。响应面分析表明,构树根皮总黄酮和多酚的最佳提取工艺为提取温度75℃、提取时间117 min、料液比1:16 g/mL、乙醇浓度70%。此条件下,构树根皮总黄酮和多酚提取量分别为23.93±0.30 mg/g和14.69±0.56 mg/g,与预测理论值接近。抗氧化实验表明,构树根皮乙醇提取物对DPPH·、ABTS^(+)·和羟自由基的半数清除浓度(IC_(50))分别为5.256μg/mL、0.259 mg/mL和0.310 mg/mL,且清除能力与其浓度呈现一定的量效关系。当提取物浓度为1.0 mg/mL时,总还原能力达到1.484±0.062。此优化实验有效可行,构树根皮乙醇提取物具有较强的抗氧化活性。本研究为构树资源的综合利用提供了一定的理论依据。

乙醇水提法提取葡萄籽油的工艺正交试验法优化研究

为解决传统溶剂法提取葡萄籽油溶剂难回收、有毒、安全性差等问题,本研究以葡萄籽为原料,采用乙醇水提法水相循环重复提取葡萄籽油,研究乙醇体积分数、料液比、pH值、时间、温度等因素对提取率的影响,在此基础上进行正交试验,并对乙醇水提法提取的葡萄籽油品质进行研究。结果表明:通过正交试验优化出葡萄籽油提取最佳条件是乙醇体积分数45%、pH值9、温度70℃,在此条件组合下葡萄籽油提取率高达30.1%,且葡萄籽油品质接近或达到国家标准。乙醇提取法满足绿色提取工艺的特点,为葡萄籽油高效提取提供一种新思路。