Optimization of Transesterification of Sunflower Oil with Ethanol using Eggshell as Heterogeneous Catalyst

Biodiesel is currently mostly produced by homogeneous catalysis. Recently, however, heterogeneous catalysis is being considered as a cheaper alternative to the homogeneous process. Heterogeneous transesterification is considered a green process. The process requires neither catalyst recovery nor aqueous treatment steps and very high yields of ethyl esters can be obtained, close to the theoretical value. However, heterogeneously catalyzed transesterification generally requires more severe operating conditions, and the performance of heterogeneous catalysts is generally lower than that of the commonly used homogeneous catalysts. This study seeks to address this problem by studying the production of biodiesel using eggshells as heterogeneous catalysts. Heterogeneous catalysts can make biodiesel production more energy efficient, and therefore less expensive, by eliminating the need for expensive purification processes that separates the catalyst from reaction products typical in the use of homogeneous catalysts. Matlab was employed for the experimental design, statistical analysis and process modeling. Fatty acid ethyl ester was produced by transesterification of sunflower oil and ethanol using calcined eggshells as a heterogeneous catalyst. To optimize the process, some important variables such as reaction temperature, molar ratio of ethanol to oil and mass weight of catalyst were selected and studied. At the following conditions: 343K of reaction temperature, ethanol to sunflower oil ratio of 9:1 and 1 mass wt% of catalyst, an optimum fatty acid ethyl  ester yield of 92% was obtained, indicating that eggshells have the potential of being used as a heterogeneous catalyst for the production of fatty acid ethyl ester from sunflower oil. Physico-chemical characterization of the fatty acid ethyl ester was performed and compared with the US Standard biodiesel properties, and it was observed that the biodiesel compared well with the standards. Keywords: Transesterification, eggshell catalyst, process optimization, sunflower oil, ethanol

Effects of Renewable Energy and Accessibility on Household’s Fuel Choices: A Case Study in Kenya

Regardless of the efforts to encourage the use of renewable energy sources such as solar and biogas in developing countries, their adoption and use is still low especially in Kenya. The purpose of this research was to investigate effects of renewable energy and accessibility on household fuel choices in Kenya among households in rural and peri-urban areas. Random sampling technique was used to select a sample of 199 households in the county of Uasin Gishu.   Data for the study were collected using a structured questionnaire and analyzed using different quantitative and qualitative statistical procedures and methods. Analysis reveals that rural households are still dependent largely on kerosene and electricity for lighting their houses and majorly firewood for cooking, while electricity and charcoal form a major source of energy for lighting and cooking in peri-urban households respectively. A small portion of households in rural (11.6%) and peri-urban (12.9%) use biogas energy for cooking.  The results also shows negative association between the use of renewable energy and the use of conventional household energy sources for cooking (firewood, kerosene and charcoal) and lighting (kerosene) implying reduction in deforestation, indoor pollution and dependency on imported fuels. Further, it was found that there is positive association between accessibility and the type of fuel used at household level for cooking indicating that nearness to diverse supplying shops selling fuel is positively associated with household energy changing behaviour.  The effects of renewable energy will reduce the use of conventional fuels and household’s energy diversification while accessibility on the other hand increases household fuel choices. The finding offers insights that could increase the uptake of renewable energy and reduce the problems associated with traditional fuels. Keywords: Household energy, renewable energy, accessibility, cooking and lighting DOI: 10.7176/JETP/9-7-04 Publication date:October 31st 201

Kinetics of Transesterification of Croton megalocarpus Oil Using Alkaline Earth Catalysts with Conventional and Microwave Heating

Transesterification kinetics of Croton megalocarpus oil to produce fatty acid methyl esters (FAME) was studied using homogeneous NaOH and heterogeneous alkaline earth Nano MgO, MgO, Nano CaO, CaO, Reoxidized CaO, SrO, and BaO catalysts. Characteristic surface, bulk, and chemical properties of the heterogeneous catalysts were obtained which included surface area, pore properties, scanning electron micrography, X-ray diffraction, basic strength, and basicity. The catalyst porosity varied as Nano MgO > Nano CaO > MgO > CaO > CaO-RO > SrO > BaO and basicity as BaO > SrO > Nano CaO > CaO RO > CaO > Nano MgO > MgO. Catalysts NaOH, BaO, SrO, and Nano CaO gave a good FAME yield (>50%), and reaction order and rate constant have been reported for these catalysts, for both conventional heating and microwave irradiation. The overall reaction for NaOH was of 1st order for microwave irradiation with respect to triglyceride and of 2nd order with respect to triglyceride under conventional heating. For the heterogeneous catalysts, the overall reaction was of 3rd order, 2nd order with respect to triglyceride and 1st order with respect to methanol for both heating methods. Reaction rate constants for microwave irradiation were higher than those for conventional heating due to faster reaction rates under such heating. BaO was the most active heterogeneous catalyst, followed by SrO and Nano CaO, which was in accordance with their basicity

Extraction de pyréthrines par le CO2 liquide et supercritique

TOULOUSE-ENSIACET (315552325) / SudocSudocFranceF

Experimental measurement and computational fluid dynamics simulation of mixing in a stirred tank: a review

Stirred tanks are typically used in many reactions. The quality of mixing generated by the impellers can be determined using either experimental and simulation methods, or both methods. The experimental techniques have evolved from traditional approaches, such as the application of hot-wire anemometry, to more modern ones like laser Doppler velocimetry (LDV). Similarly, computational fluid dynamics (CFD) simulation techniques have attracted a lot of attention in recent years in the study of the hydrodynamics in stirred tanks, compared to the empirical modelling approach. Studies have shown that the LDV technique can provide very detailed information on the spatio-temporal variations in a tank, but the method is costly. For this reason, CFD simulation techniques may be employed to provide such data at a lower cost. In recent years, both integrated experimental and CFD approaches have been used to determine flow field and to design various systems. Both CFD and LDV data reveal the existence of flow maldistribution caused by system design features, and these in turn show that the configurations that have, over the years, been regarded as standard may not provide the optimal operating conditions with regards to the system homogeneity and power consumption. The current trends in CFD studies point towards an increasing application of more refined grids, such as in large eddy simulation, to capture turbulent structures at microscales. This trend will further improve the quality of the simulation results for processes such as precipitation, in which micromixing and reaction kinetics are important

Supercritical Carbon Dioxide Extraction of Andrographolide from Andrographis paniculatu: Effect of the Solvent Flow Rate, Pressure, and Temperature

Andrographis paniculata Nees has been extensively used for traditional medicine and help against fever, dysentery, diarrhoea, inflammation, and sore throat. In this study, andrographolide, the main component of this plant was extracted from the leaves of A. paniculata using supercritical carbon dioxide. The operating pressures were varied from 7.50 to 20MPa, the temperatures were varied from 30°C to 60"C, and the flow rates were varied from 0.5 to 4mlmin-I. The best extraction condition occurred at lOMPa, 40T, and a flow rate of 2mlmK' for a 3g sample of A. paniculata ground-dried leaves. The measured extraction rate was found to be about 0.0174g of andrographolide per gram of andrographolide present in the leaves per hour of operation. The future studies must focus on the interaction between the various operating parameters such as temperature, pressure, and flow rate of supercritical carbon dioxide

Optimization of biogas production from anaerobic co-digestion of fish waste and water hyacinth

Abstract Many fresh water bodies face a great challenge of an invasive weed called water hyacinth (WH) which has great impacts on the environment, ecology, and society. Food and Agriculture Organization (FAO) estimates that over nine million tons of Fish wastes (FW) are thrown away each year. The fish waste generated poses environmental and health hazards because in most cases it is either disposed into pits or discarded onto the open grounds. Both WH and FW are potential substrates for biogas production. However, utilization of FW substrate alone has a limitation of producing a lot of amounts of volatile fatty acids (VFAs) and ammonia. Their accumulation in the digester inhibits substrate digestion. Consequently, as stand-alone it is not suitable for anaerobic digestion (AD). This can be overcome by co-digestion with a substrate like WH which has high carbon to nitrogen (C/N) ratio prior to biodigestion. Experimental variable levels for biogas were substrate ratio (WH:FW, 25–75 g), inoculum concentration (IC, 5–15 g/250 mL), and dilution (85–95 mL). Design-Expert 13 was used for optimization and results analysis. Response surface methodology (RSM) was used to examine the effects of operating parameters and identify optimum values for biogas yield. Optimum values for maximum biogas with the highest methane yield of 68% were found to be WH:FW ratio, 25:75 g, 15 g of IC, and 95 mL for dilution. The yield was 16% and 32% greater than FW and WH mono-digestion, respectively. The biogas yield was expressed as a function of operating variables using a quadratic equation. The model was significant (P < 0.05). All factors had significant linear and quadratic effects on biogas while only the interaction effects of the two factors were significant. The coefficient of determination (R 2) of 99.9% confirmed the good fit of the model with experimental variables

Enhancement of Biogas Potential for Slaughterhouse Waste by Co-digestion with Animal Wastes

This research article published by MAXWELL Scientific Publication Corp., 2021The aim of the current study was to investigate biogas production from the slaughterhouse waste codigested with animal wastes. Slaughterhouses generate organic wastes that are environmentally hazardous due to high contents of biological contaminants. The use of anaerobic digestion of the slaughterhouse waste can achieve twin objectives of waste treatment and energy production as biogas. The process is however, limited by low biogas potential of slaughterhouse waste. The study evaluated the effect of codigesting the slaughterhouse, chicken and pig wastes on biogas potential. The co-digestion test with combination ratio of 1:1, slaughterhouse waste and chicken waste produced the highest value of biogas potential of 636 L/kg-VS, which was almost double that from pure slaughterhouse waste. In addition, the substrate biodegradability, the biogas productivity and the yield were most improved at 1:1 co-digestion. The digestate from the process had high nutrient contents and a maximum of; 0.8, 2.6 and 2.7% of dry matter for total nitrogen, phosphate and Potassium respectively. The kinetic analysis of the codigestion process using modified Gompertz equation indicated a correlation between the waste biodegradability and biogas yield. The enhancement of the C/N ratio in the slaughterhouse waste by co-digestion with these wastes could be responsible for the improvement of the biogas production and yield. Future studies should focus on how the nutrient rich digestate can be appropriately applied as bio-fertilizer and on how co-digestion affects the pathogens in slaughterhouse wastes