Acid value biodiesel

As tung oil has a high acid value (AV), the esterification using solid acid catalyst, Amberlyst-15, was employed to produce biodiesel more efficiently. Optimal condition of methanol and catalyst for the esterification was established by response surface methodology. The fuel properties of tung biodiesel produced from pretreated tung oil by alkali catalyst were analyzed. 

One approach to reducing water consumption is to lower the pH of the biodiesel, either by direct acid addition or by adding acid to the wash water. Below pH 4.5, the soap dissolved in the biodiesel will be split into free fatty acids and salts. The free fatty acids stay with the biodiesel and as long as they do not exceed the Acid Value specification in ASTM D 6751 (0.5 mg KOH/g), they do not cause a problem. The salts are removed with a small amount of water (3 to 10%). 

An overview of analytical methods used to study oxidation was edited by Kamal-Eldin and Pokorny (2005). Numerous methods, including wet-chemical methods, such as acid value and peroxide value, various oxidation tests, pressurized and conventional differential scanning calorimetry (P-DSC DSC see Dunn 2000, 2006), nuclear magnetic resonance (NMR) and others, have been applied in oxidation studies of biodiesel. NMR can be used to assess the fatty acid profile of oxidized biodiesel (Knothe, 2006a). 

The acidity values of oil samples are around of 10-20 times above those found into major of the feedstock commonly used for biodiesel production. The kinetic curves reveals that when used in the concentration equal to 0.40 mmol, a reduction of 95 % on initial oleic acid content it was achieved. 

Fatty acid stmcture (composition and imsaturation degree) of vegetable oils used as feedstocks considerably affect the physical properties of biodiesel such as viscosity, cold flow properties, oxidation stability and exhaust emission profile (Knothe 2008). Even, there are many successful attempts to predict the biodiesel properties from the fatty acid composition of the plant oils. Fatty acid distribution of some common vegetable oils is given in Table 2. Higher saturated fatty acid based biodiesel has higher viscosity, cold flow temperatures, oxidation stability and calorific value while higher imsaturated fatty acid based biodiesel shows a combination of improved fuel properties as a whole (Knothe 2005 Ramos 2009 Kumar 2013). 

During long-term storage biodiesel can be easily subject to oxidation under ambient conditions due to the presence of double bonds in the chains of fatty compounds. The reaction of oxidation increases with the increasing of unsaturation level (polyunsaturated compounds are many times more reactive that monounsaturated ones). Some parameters such as acid value, peroxide value or kinematic viscosity increase when autoxidation occurs, thus the fuel s quality is affected. Degradation of the quality of this alternative fuel leads to an increase of deposits on injectors and pump parts and therefore an increase in pressure across filters. 

D7321 Particulate contamination of B1 00 and biodiesel blends by laboratory filtration EN 14104 Acid value... 

Several authors have explored the potential of Annona oil for second-generation biodiesel (AOBD) production as its low acid value and fatty acid profile (rich in oleic and palmitic acids) bestows excellent properties on AOBD, meeting the international standards ASTM D6751 (Reyes-Trejo et al., 2014) and EN14214 (Branco et al., 2010). Characterization of several Annona species showed different yields and fatty acid profiles as Table 5.5 depicts. The greatest differences have been found for palmitic acid (C16 0), oleic acid (C18 l), and Unoleic acid (C18 2), therefore affecting biodiesel properties from different Annona species. 

The degree of unsaturation of the fatty acids is normally expressed as the iodine value (IV), that is, the number of grams of iodine that have reacted with 100 g of product analyzed, under controlled experimental conditions. The higher is IV, the greater is the degree of unsaturation. For example, for biodiesel intended for haulage use, the most remunerative use, a maximum IV limit of 120 g I2 per 100 g is envisaged. 

A byproduct of vegetable oil transesterification to make biodiesel fuel, glycerol (GO) has captured our attention for several reasons, in aqueous medium, GO itself can be converted to value-added commodity products such as propylene glycol (PG), lactic acid (LA) and ethylene glycol (EG) in the presence of a metal catalyst at mild conditions (2-7). An array of metals deposited on various supports have been examined as catalysts for the above reaction (6, 7). 

Although there are numerous publications on the effect of natural and synthetic antioxidants on the stability of oils and fats used as food and feed, until recently relatively little publicly available information was available on the effect of antioxidants on the oxidative stability of biodiesel. One of the earliest studies reporting of the effects of antioxidants on biodiesel was that of Du Plessis et aL (1985), which examined storage stability of sunflower oil methyl esters (SFME) at various temperatures for 90 d. Effects of air temperature, presence of light, addition of TBHQ (see Figure 1.1) and contact with steel were evaluated by analysis of free fatty acid content, PV, kinematic viscosity, anisidine value, and induction period. Addition of TBHQ delayed oxidation of samples stored at moderate temperatures (<30°C). In contrast, under unfavorable (50°C) conditions, TBHQ was ineffective. 

Operation of the Biodiesel Cost Optimizer is fast and easy, making it possible to make large sets of simulations in a short time. This helps better understanding the different value of the different fatty acid methyl esters. It will quickly become clear, when using the Biodiesel Cost Optimizer, that oleic acid methyl esters are the preferential FAME in every biodiesel formula. Oleic acid methyl esters bring a relatively high oxidation stability (50h or more), combined with a more than acceptable CN of around 56, and excellent melting point at -19 °C. Unfortunately, pure oleic acid methyl esters are not available in the market. 

Plant oils are excellent sources of some valuable compounds such as unsaturated fatty acids, phytosterols, squalene, pigments, antioxidants, vitamins, waxes, glycolipids, and lipoproteins. Plant oils could be employed for technological uses as biodiesel, lubricants, surfactants, emulsifiers, biopolymers, and so on. Vegetable oils also can serve as appropriate sources for the production of valuable compounds having applications in food, pharmaceutical, medical, and environmental fields. Attention has been focused on various types of value-added fatty acids (polyunsaturated fatty acids, conjugated fatty... 

Official methods of chemical analysis of conventional diesel are often not adequate to characterize biodiesel. Tests for the levels of sulfur and aromatic components in biodiesel are useful but usually reveal that the concentrations of compounds containing these atoms or functional groups are very low. Analysis of biodiesel chemistry can reveal characteristics conferred by the source of the oU, the method of manufacture, and duration of storage (20, 21). For example, free and bound glycerol is measured to ascertain if biodiesel has been completely formed during synthesis. Fatty acid content, residual soaps, iodine value, peroxide value, and fatty acid composition all may reflect the quality of biodiesel (Table 1) but are unimportant and inapplicable in conventional diesel fuel quality determination. 

Biodiesel (fatty acid methyl esters) is an alternative and renewable energy source, the development of which is hoped to reduce global dependence on petroleum, as well as air pollution. Biodiesel generated Ifom a variety of vegetable oils and animal fats has characteristics similar to those associated with petro-diesel, including viscosity, volumetric heating value, cetane number, and flash point [1-3]. Several processes have thus far been developed for the production of biodiesel via acid-, alkali-, and enzyme-catalyzed... 

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