Acetic acid leaching of magnesia from magnesite via calcination

135-138In this study, magnesite mineral was first calcinated between 800-1100 K for an hour and dissolved in acetic acid solutions. The effects of temperature, solid-to-liquid ratio, reaction time, stirring speed and acid concentration on the dissolution rate of magnesia in acetic acid were investigated. It was observed that the dissolution of magnesia increased with increasing temperature, stirring speed, reaction time and acid concentration and decreased with increase in solid-to-liquid ratio. The dissolution process is controlled by pseudo first-order reaction rate. Activation energy for the reaction was calculated as 8.78 (kJ/mol)

Biodiesel production from vegetable oils by supercritical methanol

858-865Transesterification of vegetable oils in supercritical methanol are carried out without using any catalyst. Methyl esters of vegetable oils or biodiesels have several outstanding advantages among other new-renewable and clean engine fuel alternatives and can be used in any diesel engine without modification. The most important variables affecting the methyl ester yield during the transesterification reaction are molar ratio of alcohol to vegetable oil and reaction temperature. Compared to no. 2 Diesel fuel, all vegetable oils are more viscous, while the methyl esters of vegetable oils are slightly more viscous. Biodiesel has become more attractive because of its environmental benefits. The cost of biodiesel, however, is the main obstacle to commercialization. With cooking oils as raw material, viability of a continuous transesterification process and recovery of high quality glycerol as a biodiesel by-product are primary options to be considered to lower the cost of biodiesel. Supercritical methanol has a high potential for both transesterification of triglycerides and methyl esterification of free fatty acids to methyl esters for diesel fuel substitute. In supercritical methanol transesterification method, yield of conversion rises 95% in 10 min. Viscosity of vegetable oils (27.2-53.6 mm2/s) get reduced in vegetable oil methyl esters (3.59-4.63 mm2/s). The flash point values of vegetable oil methyl esters are highly lower than those of vegetable oils. An increase in density from 860 to 885 kg/m3 for vegetable oil methyl esters increases the viscosity from 3.59 to 4.63 mm2/s

Political, economic and environmental impacts of biofuels: A review

Current energy policies address environmental issues including environmentally friendly technologies to increase energy supplies and encourage cleaner, more efficient energy use, and address air pollution, greenhouse effect, global warming, and climate change. The biofuel policy aims to promote the use in transport of fuels made from biomass, as well as other renewable fuels. Biofuels provide the prospect of new economic opportunities for people in rural areas in oil importer and developing countries. The central policy of biofuel concerns job creation, greater efficiency in the general business environment, and protection of the environment. Projections are important tools for long-term planning and policy settings. Renewable energy sources that use indigenous resources have the potential to provide energy services with zero or almost zero emissions of both air pollutants and greenhouse gases. Biofuels are expected to reduce dependence on imported petroleum with associated political and economic vulnerability, reduce greenhouse gas emissions and other pollutants, and revitalize the economy by increasing demand and prices for agricultural products.Biofuel Policy Economy Environment Impacts

Competitive liquid biofuels from biomass

The cost of biodiesels varies depending on the feedstock, geographic area, methanol prices, and seasonal variability in crop production. Most of the biodiesel is currently made from soybean, rapeseed, and palm oils. However, there are large amounts of low-cost oils and fats (e.g., restaurant waste, beef tallow, pork lard, and yellow grease) that could be converted to biodiesel. The crop types, agricultural practices, land and labor costs, plant sizes, processing technologies and government policies in different regions considerably vary ethanol production costs and prices by region. The cost of producing bioethanol in a dry mill plant currently totals US$1.65/galon. The largest ethanol cost component is the plant feedstock. It has been showed that plant size has a major effect on cost. The plant size can reduce operating costs by 15-20$0.02-$0.03 per liter. Thus, a large plant with production costs of$0.29 per liter may be saving $0.05-$0.06 per liter over a smaller plant. Viscosity of biofuel and biocrude varies greatly with the liquefaction conditions. The high and increasing viscosity indicates a poor flow characteristic and stability. The increase in the viscosity can be attributed to the continuing polymerization and oxidative coupling reactions in the biocrude upon storage. Although stability of biocrude is typically better than that of bio-oil, the viscosity of biocrude is much higher. The bio-oil produced by flash pyrolysis is a highly oxygenated mixture of carbonyls, carboxyls, phenolics and water. It is acidic and potentially corrosive. Bio-oil can also be potentially upgraded by hydrodeoxygenation. The liquid, termed biocrude, contains 60% carbon, 10-20 wt.% oxygen and 30-36 MJ/kg heating value as opposed toBiomass Liquid biofuel Bio-oil Biocrude Biodiesel Bioethanol

Promising sources of energy in the near future

Fossil fuels, renewable, nuclear, or fissile fuels are the main energy sources. Fossil fuels, especially oil, are still the most popular source of energy in the world. Importance of clean and renewable energy sources (RESs) has increased significantly in recent years. The authors analyze current and future energy situation in the world. The futuristic concept of engine fuel has become the promising fuel resource which can compete with oil. The paper analyzes and discusses also the alternative energy sources in the future