Temperature effect on the viscosities of palm oil and coconut oil blended with diesel oil

One of the major difficulties in using crude vegetable oils as substitute fuels in diesel engines is their relatively high viscosities. Increasing the temperature of the crude vegetable oil, blending it with diesel oil, or the combination of both offers a simple and effective means of controlling and lowering the viscosities of vegetable oils. This work reports viscosity data, determined with a rotational bob-and-cup viscometer, for crude palm oil and cononut oil blended with diesel oil over the temperature range of 20–80°C and for different mixture compositions. All the test oil samples showed a time-independent newtonian type of flow behavior. The reduction of viscosity with increasing liquid temperature followed an exponential relationship, with the two constants of the equation being a function of the volume percentage of the vegetable oil in the mixture. A single empirical equation was developed for predicting the viscosity of these fuel mixtures under varying temperatures and blend compositions.     

Ethanolamines used for degumming of rapeseed and sunflower oils as diesel fuels

Pure vegetable oils can be used as alternative fuel for standard unmodified diesel engines, provided the oil viscosity has been lowered by heating before they enter the fuel injection system. In its role as diesel fuel, a vegetable oil has to have, among other parameters, a low acidity and low contents of phosphorus and the alkali earth metals Ca + Mg. Such parameters can be achieved by appropriate partial refining of oil by degumming. In this article, three common ethanolamines, monoethanolamine (MEA), diethanolamine (DEA) and triethanolamine (TEA), were used as degumming agents for removing non‐hydratable phospholipids from crude rapeseed and sunflower oils. Among the studied ethanolamines, MEA is the most effective for the removal of phosphorus. After degumming with MEA (0.5 wt‐%), the phosphorus content in rapeseed oil was reduced from 445 to 3.5 ppm, and from 163 to 2.2 ppm in sunflower oil. After oil treatment with MEA (1.0 wt‐%), the residual content of Ca and Mg decreased from 136 to 4.2 ppm and from 55.4 to 1.1 ppm in rapeseed oil. In sunflower oil, the values of Ca and Mg decreased from 23.9 to 1.5 ppm and from 24.6 to 1.0 ppm. The acid value of the oils also decreased after degumming with ethanolamines. The advantage of this oil treatment process is that it takes place at ambient temperature, resulting in lower production costs and simpler technology.     

Studies on phytosterol oxides. II: Content in some vegetable oils and in French fries prepared in these oils

Hydrogenated rapeseed oil/palm oil blend, sunflower oil and high-oleic sunflower oil, and French fries fried in these oils were assessed for contents of sterol oxidation products. Different oxidation products of phytosterols (7α- and 7β-hydroxy-sito-and campesterol, 7-ketosito- and 7-ketocampesterol, 5α,6α-epoxy-sito- and campesterol, 5β,6β-epoxy-sito-and campesterol, dihydroxysitosterol and dihydroxycampesterol) were identified and quantiated by gas chromatography (GC) and GC-mass spectroscopy. Rapeseed oil/palm oil blend contained 41 ppm total sterol oxides before frying operations. After two days of frying, this level was increased to 60 ppm. Sunflower oil and high-oleic sunflower oil had 40 and 46 ppm sterol oxides, respectively, before frying operations. After two days of frying operations, these levels increased to 57 and 56 ppm, respectively. In addition to campesterol and sitosterol oxidation products, small amounts of 7α- and 7β-hydroxystigmasterol were detected in the oil samples. Total sterol oxides in the lipids of French fries fried at 200°C in rapeseed oil/palm oil blend, sunflower oil, and high-oleic sunflower oil were 32, 37, and 54 ppm, respectively. The levels of total oxidized sterols, calculated per g sample, ranged from 2.4 to 4.0 ppm. In addition to the content of phytosterol oxides, full scan mass spectra of several oxidation products of stigmasterol are reported for the first time. Part of these results were presented at the 86th Annual Meeting of the AOCS, May 7–11, 1995, San Antonio, TX.     

Upgrading coal-derived liquids to diesel fuel

Distilled fractions of a coal-derived liquid from the H-Coal process were upgraded to diesel fuel by catalytic hydrotreatment. The total hydrotreated products were distilled into naphtha (<180°C) and diesel fuel fractions (>180°C) and the diesel fractions were analysed for hydrocarbon-type composition, hydrogen content and some diesel fuel properties. GC—MS-analyses were carried out on the hydrocarbon-type fractions to identify individual chemical compounds. To investigate the effect of different distillation cut points on diesel fuel yield and properties, cut points for one hydrotreated product were varied. The diesel fuel cetane numbers were correlated with percentage hydrogen, total aromatics and saturates. Cetane numbers above 40 were obtained for diesel fuels containing (i) more than 75% saturates, (ii) less than 15% total aromatics and (iii) a hydrogen content above 12.8%. Compounds identified by GC—MS-analyses (in the diesel fractions) were typical aromatic and cycloparaffin compounds. Normal-and iso-paraffin compounds were not detected. By varying the distillation cut point from 135 to 180°C, the cetane number of the residual diesel fraction improved from 37 to 44. This increase is ascribed to the removal of aromatic compounds in the 135–180°C boiling point range.     

Potential Vegetable-Based Diesel Fuels from Perkin Condensation of Furfuraldehyde and Fatty Acid Anhydrides

Domestically produced biofuels may help to reduce dependence on imported oil for powering transportation and infrastructure in the future. In this report, we reacted medium-chain and long-chain fatty anhydrides (capric, caprylic, lauric, and palmitic) with furfuraldehyde by the Perkin condensation to produce 2-n-alkenylfurans. In the second step, the 2-n-alkenylfurans were hydrogenated to form 2-n-alkyltetrahydrofurans. Basic fuel property testing (melting point, density, kinematic viscosity, derived cetane number, and calorific value) of the 2-n-alkyltetrahydrofurans indicates they are potentially useful as fuels for diesel engines. The mixture composed of 2-octyl- and 2-decyltetrahydrofuran had the best combination of fuel properties including a low melting point (−39 °C), high cetane number (63.1), high flash point (98.2 °C), and low viscosity (2.26 mm² s⁻¹, 40 °C), which compares favorably with specifications for diesel #2 and biodiesel.     

Exhaust emissions and health effects of particulate matter from agricultural tractors operating on rapeseed oil methyl ester

Exhaust emissions and their effects on the environment and human health, such as mutagenicity of particulate matter (PM) and ozone-forming potential, must be considered when using an alternative fuel. In the present work, a test engine and two agricultural tractors ran on rapeseed oil methyl ester (biodiesel) or conventional diesel fuel as well as blends thereof. The objective was to detect any disproportionately positive or negative effects depending on blend levels, because conventional diesel fuel and biodiesel can be blended in every ratio. Generally, emissions of regulated compounds changed linearly with the blend level. The known positive and negative effects of biodiesel varied accordingly. Overall, no optimal blend was found. Increasing biodiesel content of the fuel caused a linear increase in benzene emissions in the agricultural five-mode engine test, an effect that may be explained from previous studies on precombustion chemistry. In using the test engine, it was found that PM from biodiesel significantly reduced mutagenic potential compared with that from diesel fuel, although in this work PM masses were found to be reproducibly higher for biodiesel from rapeseed oil compared with conventional diesel fuel. Ozone precursors increased 10–30% when using biodiesel compared with conventional diesel fuel. Emissions of aldehydes and alkenes are mainly responsible for this effect. N₂O emissions increased when using a catalytic converter.     

Ignition delay in a palm oil and rapeseed oil biodiesel fuelled engine and predictive correlations for the ignition delay period

This paper presents the results of engine tests of biodiesels obtained by transesterification of palm oil and rapeseed oil and with fossil diesel fuel as a reference. The analysis is focused on the determination of the ignition delay and on obtaining a predictive correlation for it. The experiments show no significant difference in in-cylinder pressures at injection timing for each fuel. With biodiesel slightly lower peak cylinder pressures were observed for most engine conditions. Palm oil and rapeseed oil biodiesel gave shorter ignition delay than fossil diesel fuel due to the higher cetane number for the biodiesels. The ignition delay data were correlated as a function of the equivalence ratio, the mean cylinder pressure and mean temperature over the ignition delay interval. A comparison is made with other available correlations. The ignition delay values estimated by the new correlations are in good agreement with the experiments.     

Formulation of Canola-Diesel Microemulsion Fuels and Their Selective Diesel Engine Performance

Vegetable oils have been considered as an alternative to diesel fuel due to their comparable properties and performance. However, the high viscosity of vegetable oil causes engine durability problems with long-term usage. Vegetable oil viscosity can be reduced by blending with diesel fuel in thermodynamically stable mixtures using microemulsion fuel formulation techniques. This work focuses on the formulation of microemulsion fuels comprising diesel fuel and canola oil as the oil phase with ethanol and sec-butanol as viscosity reducers as well as 1-octanol and oleyl amine as surfactant/cosurfactant. Selective tests on an instrumented diesel engine were performed for formulated microemulsion fuels and No. 2 diesel fuel for comparison. The results show that formulated microemulsion fuels have fuel properties that meet the ASTM requirements for viscosity, cloud point, and pour point for biodiesel. Even more important, they have phase stability over a wide range of temperatures (−10 to 70 °C). Although all of the microemulsion fuels showed higher fuel consumption than diesel fuel, some of the microemulsion fuels had significantly reduced CO and NO_x emissions as well as reduced particulates when compared to baseline diesel fuel. The research demonstrates the potential of these microemulsion fuels as alternative to neat diesel fuel.     

Cold flow properties of fuel mixtures containing biodiesel derived from animal fatty waste

The aims of the present study were to evaluate the cold temperature behavior of methyl esters of vegetable and animal origin and of their mixtures with fossil diesel fuel, as well as to investigate the effectiveness of different depressants. Various blends of rapeseed oil methyl esters, linseed oil methyl esters, pork lard methyl esters and fossil diesel fuel were prepared, and both cloud point and cold filter plugging point (CFPP) were analyzed. It was found that mixtures with CFPP values of –5 °C and lower may contain up to 25% of pork lard methyl esters; whereas the ratio of summer fossil diesel fuel and rapeseed oil methyl esters may vary over a wide range, i.e. such mixtures can be used in a diesel engine in the summer. In the transitory periods it is possible to use up to 20% animal and vegetable ester blends (3 : 7) with winter fossil diesel, whereas only up to 5% of esters can be added to the fuel used in winter. In order to improve the cold properties of rapeseed oil, pork lard and linseed oil methyl ester mixtures, various additives were tested. Depressant Viscoplex 10–35 with an optimal dose of 5000 mg/kg was found to be the most effective.     

Emission Reduction of Regenerative Fuel Powered Co-Generation Plants with SCR- and Oxidation-Catalysts

Since the beginning of combustion engine development in this recent century various different fuels have been successfully tested. Diesel engines have been adapted to fuels made from mineral oils because of the rising importance and the cheapness in comparison to other fuels. On the other hand, it is possible to burn regenerative fuels in engines and achieve some significant advantages in comparison to fossil diesel fuel. This is, for example, a closed carbon dioxide (CO₂) cycle which causes no green house effect. It is possible to extract oil from various seeds like rapeseed. It is also possible to burn used oil from the food processing industry or waste grease and oil from food recycling companies. The great advantages: (1) food recycling oils can produce energy instead of use as animal food, and (2) as nobody knows exactly the consistency of the collected oils, poisonous pollution is possible. These regenerative fuels can be burned without any further processing in special adapted diesel engines, for example an Elsbett engine, or in precombustion engines with large swept volumes. Most researchers focused on operating diesel engines with regenerative fuels and reducing the emissions caring only about regulated exhaust components. In comparison to these studies it is necessary to learn more about the emissions beyond the exhaust regulations. Additionally emission reduction is possible by using an SCR-catalyst (selective catalytic reduction) to reduce the NO₂ combined with an oxidation-catalyst which reduces any kind of oxidisable emissions. The TU München, Lehrstuhl für Energie- und Umwelttechnik der Lebensmittelindustrie, operates a small co-generation plant with the ability of analysing the standard emission components (CO, NO₂, HC, particles, CO₂, O₂) and unregulated components (SO₂, NH₃, polycyclic aromatic hydrocarbons (PAH), aldehyde, ketone). The emissions show some significant differences in comparison to fossil diesel fuel which is caused by the diversity of each fuel. Results of an investigation on four different fuels (wastefat methyl ester (WME), rapeseed methyl ester (RME), rapeseed oil and diesel fuel) burned in a small co-generation plant with a SCR- and oxidation-catalyst will be presented. A comparison to the emissions before and after the catalysts will be shown additionally to the results of the different reduction potential of diesel fuel, methyl ester or untreated oils. The combination of regenerative fuel and catalyst shows good potential for reducing the emissions. Furthermore the use of regenerative fuels is a sustainable production of energy with an overall efficiency of almost 90%. Regenerative fuels based on vegetable oils and waste fat are a valuable form of energy and have some significant advantages in comparison to diesel fuel, like an almost closed carbon dioxide cycle, rapid biological decomposition and lower CO, HC and particle emissions. Regenerative fuels should also meet minimum standards discussed in the paper to avoid the risk of engine damage and to reduce emissions.     

Rheology of vegetable oil analogs and triglycerides

The rheological properties of two complex mixtures of short-chain triglycerides were experimentally determined. Dynamic or absolute viscosities of the mixtures were measured for shear rates of 0.32 to 64.69 s⁻¹ at temperatures between 25 and 80°C. The compositions of the mixtures were based on the oil of the plant species Cuphea viscosissima VS-320, a natural source of short-chain triglycerides. The dynamic viscosities of these mixtures were compared to those of a traditional vegetable oil (peanut oil) and diesel fuel. The results of this comparison were used to make estimates of the performance of such triglyceride mixtures as diesel fuel substitutes, since viscosity can be a key indicator of fuel performance for possible substitute diesel fuels. The crystallization temperatures of these two mixtures were also determined experimentally, and the effects of crystallization on fuel performance were projected. Additionally, the dynamic viscosities of pure triglycerides from C6∶0 to C18∶0 at 75°C were plotted vs. chain length. These viscosities were measured at high shear rates (>6 s⁻¹) where dynamic viscosity is shear-independent. An obvious trend in the relationship between triglyceride chain length and viscosity was observed. A second-order regression was used to obtain an equation for this relationship. This equation was used as a model for composition dependence of viscosity. This model was applied to the viscosities of the triglyceride mixtures examined here. There was good agreement between the model and the actual, measured viscosity values determined in this study.     

Improving the low-temperature properties of alternative diesel fuels: Vegetable oil-derived methyl esters

This work explores near-term approaches for improving the low-temperature properties of triglyceride oil-derived fuels for direct-injection compression-ignition (diesel) engines. Methyl esters from transesterified soybean oil were evaluated as a neat fuel and in blends with petroleum middle distillates. Winterization showed that the cloud point (CP) of methyl soyate may be reduced to −16°C. Twelve cold-flow additives marketed for distillates were tested by standard petroleum methodologies, including CP, pour point (PP), kinematic viscosity, cold filter plugging point (CFPP), and low-temperature flow test (LTFT). Results showed that additive treatment significantly improves the PP of distillate/methyl ester blends; however, additives do not greatly affect CP or viscosity. Both CFPP and LTFT were nearly linear functions of CP, a result that compares well with earlier studies with untreated distillate/methyl ester blends. In particular, additives proved capable of reducing LTFT of neart methyl esters by 5–6°C. This work supports earlier research on the low-temperature properties; that is, approaches for improving the cold flow of methyl ester-based diesel fuels should continue to focus on reducing CP.     

Oxidative Desulfurization of Hydrocarbon Fuels

New requirements for very low sulfur content (10 ppm) in liquid motor fuels demand novel approaches for ultra-deep desulfurization. For production of near-zero-sulfur diesel and low-sulfur fuel oil, removal of refractory sulfur compounds, like 4,6-dimethyldibenzothiophene and other alkyl-substituted thiophene derivatives, is necessary. Elimination of these compounds by hydrodesulfurization (HDS) requires high hydrogen consumption, high pressure equipment, and new catalysts. Various oxidative desulfurization processes, including recent advances in this field for diesel fuels, and the drawbacks of this technology in comparison with HDS are examined and discussed. It is shown that the oxidation of sulfur compounds to sulfones with hydrogen peroxide allows for production of diesel fuels with a sulfur content of 10 ppmw or lower at atmospheric pressure and room temperature. The gas phase oxidative desulfurization of sulfur compounds with air or oxygen is feasible at atmospheric pressure and higher temperatures: 90–300 °С and offers better economic solutions and incentives.     

Performance and emission study of waste anchovy fish biodiesel in a diesel engine

Waste anchovy fish oils transesterification was studied with the purpose of achieving the conditions for biodiesel usage in a single cylinder, direct injection compression ignition. With this purpose, the pure biodiesel produced from anchovy fish oil, biodiesel-diesel fuel blends of 25%:75% biodiesel-diesel (B25), 50%:50% biodiesel-diesel (B50), 75%:25% biodiesel-diesel (B75) and petroleum diesel fuels were used in the engine to specify how the engine performance and exhaust emission parameters changed. The fuel properties of test fuels were analyzed. Tests were performed at full load engine operation with variable speeds of 1000, 1500, 2000 and 2500 rpm engine speeds. As results of investigations on comparison of fuels with each other, there has been a decrease with 4.14% in fish oil methyl ester (FOME) and its blends' engine torque, averagely 5.16% reduction in engine power, while 4.96% increase in specific fuel consumption have been observed. On one hand there has been average reduction as 4.576%, 21.3%, 33.42% in CO₂, CO, HC, respectively; on the other hand, there has been increase as 9.63%, 29.37% and 7.54% in O₂, NO_x and exhaust gas temperature has been observed. It was also found that biodiesel from anchovy fish oil contains 37.93 wt.% saturated fatty acids which helps to improve cetane number and lower NO_x emissions. Besides, for biodiesel and its blends, average smoke opacity was reduces about 16% in comparison to D2. It can be concluded that waste anchovy fish obtained from biodiesel can be used as a substitute for petroleum diesel in diesel engines.     

Utilization of ethyl ester of waste vegetable oils as fuel in diesel engines

Jordan relies heavily on expensive and unreliable imported oil. Therefore, this study was initiated to investigate the potential of ethyl ester used as vegetable oil (VO; biodiesel) to substitute oil-based diesel fuel. The fuels tested were several ester/diesel blends including 100% ester in addition to diesel fuel, which served as the baseline fuel. Variable-speed tests were run on all fuels on a standard test rig of a single-cylinder, direct-injection diesel engine. Tests were conducted to compare these blends with the baseline local diesel fuel in terms of engine performance and exhaust emissions. The results indicated that the blends burned more efficiently with less specific fuel consumption, and therefore, resulted in higher engine thermal efficiency. Furthermore, the blends produced less carbon monoxide and unburned hydrocarbons than diesel fuel. The 100% ester fuel and the blend of 75:25 ester/diesel gave the best performance while the 50:50 blend consistently resulted in the lowest amounts of emissions over the whole speed range tested.     

Physico-chemical characteristics of palm-based oil blends for the production of reduced fat spreads

The effect of blending and interesterification on the physicochemical characteristics of fat blends containing palm oil products was studied. The characteristics of the palm-based blends were tailored to resemble oil blends extracted from commercial reduced fat spreads (RFS). The commercial products were found to contain up to 20.4% trans fatty acids, whereas the palm-based blends were free of trans fatty acids. Slip melting point of the blends varied from 26.0–32.0°C for tub, and 30.0–33.0°C for block RFS. Solid fat content at 5 and 10°C (refrigeration temperature), respectively, varied from 10.9–19.7% and 8.5–17.6% for tub, and 28.2–38.6% and 20.8–33.5% for block RFS. Melting enthalpy of the tub RFS varied from 35.0–54.3 J/g and that of block RFS varied from 58.0–75.4 J/g. To produce block RFS, 65% palm oil (PO) and 18% palm kernel olein (PKOo) could be added in a ternary blend with sunflower oil (SFO), but only 47% PO and 10% PKOo are suggested for tub RFS. Higher proportion of PO, i.e., 72% for block RFS and 65% for tub RFS, could be used after the ternary blend was interesterified. Although a ternary blend of palm olein (POo)/SFO/PKOo was not suitable for RFS formulation, after interesterification as much as 90% POo and 26% PKOo could be used in the block RFS formulation. For tub RFS a maximum of 30% POo was found suitable.     

Limitations of the use of cetane index for alternative compression ignition engine fuels

The cetane number of a fuel is an important factor in determining the quality of ignition in compression ignition (CI) engines. The significance of accurate measurement of cetane number has become even greater since the use of alternative fuels and modern CI engines. In this work, the comparison of different methods of cetane value measurement for fuels with different chemical composition such as ultra low sulfur diesel (ULSD), synthetic jet fuel (S-8) and military grade jet fuel (JP-8), trace amounts of additives and biodiesel blends under different conditions is reported. The cetane index was calculated by ASTM D4737 and ASTM D976 and the derived cetane number (DCN) was measured using an Ignition Quality Tester (IQT) as a basis of comparison with the cetane index. The best agreement among three methods was observed for ULSD, while S-8 showed the largest discrepancy. The cetane indices for S-8 were 70.2 and 67.3 calculated using D4737 and D976 respectively, while the DCN was 52.8. The addition of biodiesel to ultra low sulfur diesel (ULSD) fuel alters the chemical properties of the fuel. The derived cetane number reflected the increase in ignition quality with the addition of biodiesel while calculations for cetane index did not. The cetane indices for a commercial B20 were 45.30 and 46.70 while the DCN showed a significantly higher value of 48.50. Blending 5% oxidized biodiesel with ULSD caused an 8% increase in the derived cetane number of the blend. The cetane index of the 5% biodiesel was not significantly affected by oxidation. The effects of fuel additives on cetane measurements were reflected in the DCN measurements, but not with cetane indices.     

Effect of FFA of Crude Rice Bran Oil on the Properties of Diesel Blends

Crude rice bran oil (CRBO) with high free fatty acid (FFA) content is not suitable for eating purposes, however, it can be used as a fuel to partially replace or fully replace No.2 diesel. The main objective of the present work was to analyse the effect of FFA content of CRBO on the combustion properties such as viscosity, calorific value, volatility and aniline point. CRBO with different FFAs were collected and mixed with No.2 diesel to prepare CRBO-diesel blends. It was observed that the viscosity of the blends increased with increase in FFA while the calorific value decreased. Significant variations were observed in the distillation curve for the CRBO blends with different FFA. Aniline point of the blends was 10–15% lower than that of diesel and it is indirectly proportional to the FFA of CRBO in the blend. Experimental results showed that the combustion properties of CRBO are the function of the FFA in the oil. As a dilute blend with diesel, CRBO with high FFA content showed comparable combustion properties to that of diesel. The properties differed in magnitude by 10–15% when compared with diesel. From the present investigation it is concluded that in blended form, CRBO with high FFA can be a potential resource to utilize it as an alternative fuel for CI (compression ignition) engines.     

Temperature-dependent kinematic viscosity of selected biodiesel fuels and blends with diesel fuel

The kinematic viscosities of four biodiesel fuels—two natural soybean oil methyl esters, one genetically modified soybean oil methyl ester, and one yellow grease methyl ester—and their 75, 50, and 25% blends with No. 2 diesel fuel were measured in the temperature range from 20 to 100°C in steps of 20°C. The measurements indicated that all these fuels had viscosity-temperature relationships similar to No. 2 diesel fuel, which followed the Vogel equation as expected. A weighted semilog blending equation was developed in which the mass-based kinematic viscosity of the individual components was used to compute the mixture viscosity. A weight factor of 1.08 was applied to biodiesel fuel to account for its effect on the mixture viscosity. The average absolute deviation achieved with this method was 2.1%, which was better than the uncorrected mass average blending equation that had an average absolute deviation of 4.5%. The relationship between the viscosity and the specific gravity of biodiesel fuels was studied. A method that could estimate the viscosity from the specific gravity of biodiesel fuel was developed. The average absolute deviation for all the samples using this method was 2.7%. The accuracy of this method was comparable to the weighted mass-based semilog blending equation.     

Efficient Immobilization of Lecitase in Gelatin Hydrogel and Degumming of Rice Bran Oil Using a Spinning Basket Reactor

Immobilization of Lecitase (Phospholipase A1) in gelatin hydrogel and its stability is studied with a view to utilizing the immobilized enzyme for degumming rice bran oil. Excellent retention of enzyme activity (>80%) is observed in hydrogel containing 43.5% gelatin crosslinked with glutaraldehyde. Compared to the free enzyme which has a broad pH-activity profile (6.5–8.0), the activity of the immobilized enzyme is strongly dependent on pH and has a pH-optimum of pH 7.5. The optimum temperature of enzyme activity increases from 37 to 50 °C. Compared to the free enzyme which loses all its activity in 72 h at 50 °C, the immobilized enzyme retains its activity in full. The immobilized enzyme has been used efficiently in a spinning basket bioreactor for the degumming of rice bran oil with 6 recycles without loss of enzyme activity. The phosphorus content of the oil decreases from 400 ppm to 50–70 ppm in each cycle. After charcoal treatment and dewaxing, a second enzymatic treatment brings down the phosphorus content to <5 ppm.