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排序方式: 共有6527条查询结果,搜索用时 15 毫秒
1.
Callistus Nonso Ude Dominic Okechukwu Onukwuli Jonah Chukwudi Umeuzuegbu Chinemelum Chukwujekwu Chukwuka 《化学工程与技术》2021,44(1):65-76
The heterogeneous catalysis of transesterification of gmelina seed oil to biodiesel is evaluated. The oil was extracted from the seeds with n‐hexane by solvent extraction and characterized to determine its physiochemical properties. Response surface methodology was applied to optimize the effect of process variables on the biodiesel yield. The base‐activated clay catalyst performed as montmorillonite clay with the characteristic property of a Brønsted acid. It has an improved surface area after activation that enhanced its catalytic activity on transesterification reaction. Under optimal conditions, the biodiesel yield was 70.1 %, thus demonstrating that the model predicted well the biodiesel production. 相似文献
2.
《International Journal of Hydrogen Energy》2022,47(88):37401-37414
The performance of Microbial electrolysis cell (MEC) is affected by several operating conditions. Therefore, in the present study, an optimization study was done to determine the working efficiency of MEC in terms of COD (chemical oxygen demand) removal, hydrogen and current generation. Optimization was carried out using a quadratic mathematical model of response surface methodology (RSM). Thirteen sets of experimental runs were performed to optimize the applied voltage and hydraulic retention time (HRT) of single chambered batch fed MEC operated with dairy industry wastewater. The operating conditions (i.e) an applied voltage of 0.8 V and HRT of 2 days that showed a maximum COD removal response was chosen for further studies. The MEC operated at optimized condition (HRT- 2 days and applied voltage- 0.8 V) showed a COD removal efficiency of 95 ± 2%, hydrogen generation of 32 ± 5 mL/L/d, Power density of 152 mW/cm2 and current generation of 19 mA. The results of the study implied that RSM, with its high degree of accuracy can be a reliable tool for optimizing the process of wastewater treatment. Also, dairy industry wastewater can be considered to be a potential source to generate hydrogen and energy through MEC at short HRT. 相似文献
3.
《International Journal of Hydrogen Energy》2022,47(96):40582-40589
The objective of this study is to investigate the impact of biomass feeding location on rice husk gasification for hydrogen production. By comparing the results between top-feed and bottom-feed of the feedstock of the fluidized bed biomass gasification at the reaction temperature between 600~1000 °C and ER = 0.2, 0.27, and 0.33 without steam, the optimum low heating value was increase by 2.35 kJ/g-rice husk by the top-feed to gasifier. Although the yield of hydrogen was decreased by 42% for the rice husk gasification by the top-feed operation, the yield of CO, CO2, and CH4 were highly increased, which enhancing the heating value of the effluent gas. The study results suggested the potential route of the biomass gasification at the different feeding location. 相似文献
4.
5.
《Ceramics International》2021,47(22):31457-31469
The present work investigated the effects of thermal cycles in air on the tensile properties of a two-dimensional carbon fibre reinforced silicon carbide composite (2D C/SiC) prepared by chemical vapour infiltration at different heating rates. The composite was exposed to different cycles of thermal shock between 20 °C and 1300 °C in air. The damage mechanisms were investigated by AE online monitoring and fractured morphology offline analysis. The tensile strength of 2D-C/SiC decreases with increasing thermal cycles. However, the modulus only decrease within 40 cycles. Due to oxidation, with the decrease in heating rate, the residual properties of the material decrease more obviously. Meanwhile, the results of AE online monitoring and fracture analysis show that the matrix damage is more serious at higher heating rate and that more delamination occours in tensile fractures. The above results indicate that for the thermal shock of 2D C/SiC composites in air, oxidative damage plays a key role in the residual properties. 相似文献
6.
Andrea Luca Tasca Eleonora Stefanelli Anna Maria Raspolli Galletti Riccardo Gori Gemma Mannarino Sandra Vitolo Monica Puccini 《化学工程与技术》2020,43(12):2382-2392
Hydrothermal carbonization of sewage sludge was carried out with the aim to evaluate the influence of process severity and initial solid content. Response surface methodology was applied to model yield and C yield responses. Enhanced dewaterability performance was recorded under mild processing conditions. The treatment promoted concentration and immobilization of Pb, Cd, Ni, Zn, and Cu. Variation of the solid content showed a stronger influence than severity on average yield and C yield. Higher heating values (HHVs) and energy retention efficiencies (EREs) of hydrochars obtained at the lowest solid content displayed the lowest values. Hence, the energy requirements of a first dewatering step should be compared with the related improvement in terms of HHV and ERE when sludge is used as feedstock. 相似文献
7.
《能源学会志》2020,93(5):2033-2043
The present study deals with the optimization of process parameters and thermocatalytic pyrolysis of Cascabela thevetia (CT) seeds in a semi-batch cylindrical-shaped reactor. Response surface methodology (RSM) was employed for the optimization of process variables, while commercial catalysts CaO and Al2O3 were used for catalytic pyrolysis. From results, it was concluded that 525 °C temperature, 75 °C min−1 heating rate, and 75 mL min−1 flow of nitrogen yielded maximum pyrolytic liquid (45.26 wt%) while with the attendance of catalysts at 20 wt% increased the yield of pyrolytic liquid (49.12 wt% and 46.87 wt% for CaO and Al2O3 respectively). Optimization outcomes displayed that linear and quadratic terms of utilized factors were more noteworthy while interaction effects between the factors were not significant. Further, characterization of pyrolytic oil established that utilization of catalysts expressively enhanced its properties by reducing viscosity and boosted the calorific value. FTIR examination of pyrolytic oil showed that the attendance of phenols, ethers, alcohols, ketones, alkanes, acids, etc., while 1H NMR results supported the FTIR results. GC-MS analysis showed a substantial reduction of phenols and oxygen-rich products and boost the development of alcohol and aldehydes in pyrolytic oil with the introduction of catalysts. These parameters indicate improved properties of pyrolytic oil, which intensified its bioenergy capabilities. 相似文献
8.
The effect of process interaction and response surface optimization of hydrogen-rich syngas production by catalytic carbon dioxide (CO2) reforming of methane (CH4) was evaluated. The Box-Behnken design was applied to investigate the influence of CH4 partial pressure, CO2 partial pressure, and temperature on the hydrogen yield. The analysis of variance indicated that temperature and CH4 partial pressure had the most significant impact on the hydrogen yield. Under optimum conditions a maximum hydrogen yield of 71.38 % was achieved. Model validation with the ideal conditions confirmed close agreement of the predicted hydrogen yields with experimental values. 相似文献
9.
以南湖菱为研究对象,选取不同种类的无硫护色剂(L-半胱氨酸、柠檬酸、乙二胺四乙酸二钠、抗坏血酸)进行护色研究,以南湖菱果皮的L*值变化量指标进行单因素试验;在单因素试验的基础之上,以南湖菱果皮的△E值变化量指标,利用Box-Behnken设计四因素三水平进行响应面试验,建立各因素与响应值之间的数学模型,确定最佳护色工艺。结果显示,四种护色剂对南湖菱表皮L~*值的提高具有一定的效果,其中柠檬酸、抗坏血酸、乙二胺四乙酸二钠对L~*值增加幅度10%以上,但是L-半胱氨酸对L~*值增加幅度则低于3%;当处理时间5.00min、抗坏血酸浓度1.00%、柠檬酸浓度1.00%、乙二胺四乙酸二钠浓度为0.60%时,对南湖菱的△E值提升效果最好,理论值可达12.66%,经验证试验,该护色工艺对南湖菱△E值为12.31%,符合模型预期。 相似文献
10.
《International Journal of Hydrogen Energy》2020,45(42):22260-22270
Production of high grade cellulolytic enzymes from waste agricultural biomass would valorise these wastes to valuable products as well as avoid the pollution problems associated with landfilling of the biomass. In the present study, waste date palm (Phoenix dactylifera) seeds were valorised for cellulase production from Cellulomonas uda NCIM 2353 and for its subsequent usage in biohydrogen production. Optimization of key operational parameters such as date seed concentration, xylose, casein and initial media pH were performed using central composite design to obtain the maximum enzyme yield. The optimum values obtained were (g/L): date seed concentration 30.65, xylose concentration 0.55, casein 7.00 and pH 7.40 for a determination coefficient of 0.999. The results demonstrated a higher prediction accuracy of response surface methodology as the cellulase activity increased six fold (175.96 IU/mL) after optimization. The optimum pH and temperature of purified cellulase was 7 and 50 °C respectively where the enzyme retained nearly 80% of activity upto 180 min. Enzymatic hydrolysis studies showed that a high saccharification efficiency of 60.5% was obtained for acid pretreated sugarcane bagasse by the indigenous cellulase, equivalent to the performance of commercial cellulase. Further, the as-obtained reducing sugars were decomposed by Clostridium thermocellum to produce biohydrogen of maximum concentration 187.44 mmol/L at end of 24 h of fermentation. Results show that date seed substrate based cellulase protein can be employed for industrial processes of biohydrogen production. 相似文献