Insoluble Gums Research Articles

Survey on Antioxidants Used as Additives to Improve Biodiesel’s Stability to Degradation through Oxidation

A major problem that limits the use of biodiesel is maintaining the fuel at the specified standards for a longer period. Biodiesel oxidizes much more easily than diesel, and the final oxidation products change its physical and chemical properties and cause the formation of insoluble gums that can block fuel filters and the supply pipes. This instability of biodiesel is a major problem and has not yet been satisfactorily resolved. Recently, the use of biodiesel has increased quite a lot, but the problem related to oxidation could become a significant impediment. A promising and cost-effective approach to improving biodiesel’s stability is to add appropriate antioxidants. Antioxidants work better or less effectively in different biodiesel fuels, and there is no one-size-fits-all inhibitor for every type of biodiesel fuel. To establish a suitable antioxidant for a certain type of biodiesel, it is necessary to know the chemistry of the antioxidants and factors that influence their effectiveness against biodiesel oxidation. Most studies on the use of antioxidants to improve the oxidative stability of biodiesel have been conducted independently. This study presents an analysis of these studies and mentions factors that must be taken into account for the choice of antioxidants so that the storage stability of biodiesel fuels can be improved.

Effect of engine parameters, combustion and emission characteristics of diesel engine with dual fuel operation

Candle nut oil was produced from candle nut seeds by the process of crushing and filtering. The candle nut biodiesel was prepared by a two-step co-solvent esterification process and is found to be one of the best alternate fuels for running the diesel engine. The oxidation stability of the candle nut biodiesel was found to be poor and this leads to high acid value and inception of insoluble gums and dregs or scum that can block the fuel filters. Soap nut oil was extracted from soap nut seeds by the process of crushing and filtering. The soap nut biodiesel was prepared by transesterification process and has higher oxidation stability compared to candle nut biodiesel. Similarly, the cold filter plugging point of candle nut biodiesel is good compared to soap nut biodiesel and it depends upon the amount of saturated fat. Hence the mixing of soap nut biodiesel and candle nut biodiesel will increase the properties for the smooth run of engine with fewer emissions compared to diesel. In this work, engine performances and exhaust contents were evaluated for various blends of mixed soap nut biodiesel and candle nut biodiesel.

Experimental investigations on mixing of candle nut and soap nut biodiesels blended with diesel for diesel engines

Candle nut oil was produced from candle nut seeds by the process of crushing and filtering. The candle nut biodiesel was prepared by two-step co-solvent esterification process and is found to be a one of the best alternate fuel for running the diesel engine. The oxidation stability of the candle nut biodiesel was found to be poor and this leads to high acid value and inception of insoluble gums and dregs or scum that can block the fuel filters. Soap nut oil was extracted from soap nut seeds by the process of crushing and filtering. The soap nut biodiesel was prepared by transesterification process and has higher oxidation stability compared to candle nut biodiesel. Similarly, the cold filter plugging point of candle nut biodiesel is good compared to soap nut biodiesel and it depends upon the amount of saturated fat. Hence the mixing of soap nut biodiesel and candle nut biodiesel will increase the properties for the smooth run of engine with fewer emissions compared to diesel. In this work, engine performances and exhaust contents are evaluated for various blends of mixed soap nut biodiesel and Candle nut biodiesel.

Unlocking the potential of walnut husk extract in the production of waste cooking oil-based biodiesel

Biodiesel has a lower oxidation stability index (OSI) than mineral diesel fuel. Its consequential oxidation products and deteriorated physical and chemical properties of fuel are associated with engine operation challenges such as the formation of insoluble gums that can plug fuel filters. Given the fact that oxidation leads to barriers for commercial use of biodiesel, addition of appropriate antioxidants into biodiesel is a promising and cost-effective approach to overcome this challenge. Although synthetic antioxidants such as propyl gallate (PG) are frequently used to counter the oxidation process of biodiesel, PG is a designated carcinogen. In light of that, this study was conducted aiming at introducing walnut husk methanolic extract (WHME) as a more sustainable antioxidant to replace PG in waste cooking oil (WCO) methyl esters. Moreover, to facilitate the commercialization of the new product, a comprehensive environmental investigation and comparison with the conventional counterpart, i.e., PG, was performed using life cycle assessment (LCA) approach. To enhance the eco-friendly features of the natural antioxidant, a solar photovoltaic-driven extraction process based on methanol (as reagent) was used in extracting polyphenols from walnut husk. The results showed that the induction period of WCO methyl esters was prolonged from 1.2 h to more than 3 h (meeting the ASTM D6751 standards) using 5000 ppm and 250 ppm of WHME and PG, respectively. More specifically, 20-fold more natural antioxidants would be required to meet the international standards. However, since walnut-producing countries are responsible for 42.4% of global biodiesel production on one hand and the cost-effectiveness of walnut husks on the other hand, their valorization could attract the attention of the global biodiesel industry. Moreover, this study highlights the considerable environmental and health benefits of turning this bio-waste product into a value-added antioxidant fuel additive. The LCA results showed that the developed bio-antioxidant was more effective in different damage categories compared with PG, i.e., 0.32% in ecosystem quality, 12.13% in human health, 8.37% in climate change, and 614% in resource. Overall, the WHME obtained through solar photovoltaic-driven extraction process could outcompete PG from the environmental perspective.

Refining of crude rubber seed oil as a feedstock for biofuel production

Crude rubber seed oil is a potential source for biofuel production. However it contains undesirable impurities such as peroxides and high oxidative components that not only affect the oil stability, colour and shelf-life but promote insoluble gums formation with time that could cause deposition in the combustion engines. Therefore to overcome these problems the crude rubber seed oil is refined by undergoing degumming and bleaching process. The effect of bleaching earth dosage (15–40 wt %), phosphoric acid dosage (0.5–1.0 wt %) and reaction time (20–40 min) were studied over the reduction of the peroxide value in a refined crude rubber seed oil. The analysis of variance shows that bleaching earth dosage was the most influencing factor followed by reaction time and phosphoric acid dosage. A minimum peroxide value of 0.1 milliequivalents/gram was achieved under optimized conditions of 40 wt % of bleaching earth dosage, 1.0 wt % of phosphoric acid dosage and 20 min of reaction time using Response Surface Methodology design.

Experimental Study on Storage and Oxidation Stability of Bitter Apricot Kernel Oil Biodiesel

Worldwide biodiesel is accepted as a substitute for mineral diesel for its almost similar physical and chemical properties. Because biodiesel is produced from vegetable oil, animal fat, or waste frying oil and is composed of a combination of saturated and unsaturated fatty acids, this makes it prone to oxidation with time. As a result of the oxidation, insoluble gums and deposits are formed, which adversely affect the characteristics of the biodiesel and result in corrosion of engine components, such as injectors, piston rings, piston liners, etc., during engine running. In this present study, storage and oxidation stability of biodiesel produced from bitter apricot kernel oil were investigated for 6 months under dark and sunlight storage conditions without being exposed to air. Five antioxidants in small quantity, viz., tert-butylhydroquinone, butylated hydroxytoluene, butylated hydroxyanisole, pyrogallol, and propyl gallate, one per sample, were used to enhance the induction period. The result shows tha...

Effect of Reynolds Number on Deposition in Fuels Flowing Over Heated Surfaces

An increasing demand is being put on the fuel as a heat sink in modern aircraft. In the end, the fuel flows through the atomizer, which is both the hottest part in the thermal history of the fuel and the most critical for resisting deposition. Most studies have concentrated on the chemistry of deposition and in recent years there have been modeling efforts. Deposition is really the end product of a coupling between heat transfer to the fuel, chemical reactions to form insoluble gums, followed by the transport of these gums to the surface to form deposits. There is conflicting evidence and theory in the literature concerning the effect of turbulence on deposition, i.e., whether deposition increases or decreases with increasing Reynolds number. This paper demonstrates, through a heat transfer analysis, that the effect of the Reynolds number depends upon the boundary/initial conditions. If the flow is heated from the surface, deposition decreases with increasing Reynolds number; however, for isothermal flows, i.e., preheated, deposition can increase with the Reynolds number.

Catalytic coprocessing of waste plastics and petroleum residue into liquid fuel oils

Waste plastics of different types were catalytically coprocessed with petroleum residue of light Arabian crude oil in the presence of a number of catalysts. The purpose of the study was to explore effects of various conditions such as catalyst type, amount of catalyst, reaction time, pressure and temperature on the product distribution. The waste plastic studied included low-density polyethylene (LDPE), high-density polyethylene (HDPE), polystyrene (PS) and polypropylene (PP). A series of single (waster plastic with catalyst) and binary (waste plastic and residue with catalyst) reactions were carried out in an autoclave reactor under variable reaction conditions. The reaction conditions used were 1, 3 and 5 wt.% catalysts, 30–120 min reaction time, 400–430 °C reaction temperature and 500–1200 psi hydrogen pressure. The product distribution achieved for residue/plastic/catalyst system showed higher yields of liquid fuels as compared to residue/plastic system. Hydrocarbon gases were formed as well along with heavy oils, insoluble gums and coke. At the reaction conditions of 3 wt.% NiMo catalyst, 90 min reaction time, 1200 psi hydrogen gas pressure, 430 °C temperature and residue to plastic feed ratio of 3:2 (wt.) afforded maximum conversion of the plastics into liquid fuel oils.

Protection of biodiesel based on sunflower oil from oxidative degradation by natural antioxidants

SUMMARY Biodiesel as an alternative diesel fuel obtained by transesterification of vegetable fats and oils, using alcohol in the presence of a catalyst, has some advantages such as reduced emissions of unburned hydrocarbons, carbon monoxide, sulfates, polycyclic aromatic hydrocarbons, and particular matter, but its drawback, of being more prone to oxidation than petroleum-based diesel fuel, can cause the fuel to become acidic (cause fuel system corrosion) and to form insoluble gums and sediments and consequently increase its viscosity. In this study, in order to increase the stability of biodiesel based on high oleic acid sunflower oil against oxidation process during the storage and distribution, different percents [0.01%, 0.02%, 0.05%, 0.1%, and 0.2% (w/v)] of maize flour contaminated by mycotoxins, thus useless for human consumption, were added as natural antioxidants. The antioxidant effect increased with concentration up to an optimal level. Above the optimal level, the increase in antioxidant effect with its concentration was relatively small. Oxidative stability of biodiesel was determined using two parallel methods, the Schaal oven storage test (at 70°C) and the Rancimat method (at 110°C). The induction times obtained by the Rancimat method were more similar to the values determined by the oven test. The highest protective effect was observed in samples containing 0.1% (w/ v) of added antioxidants. RESUMEN Biodiesel, como el combustible diesel alternativo, obtenido por la transesterificación de las grasas y aceites vegetales, utilizando el alcohol en la presencia de catalizador, tiene algunas ventajas, como la disminuida descarga de los hidratos de carburo no combustidos, monóxido de carbón, compuestos de azufre, carbohidratos policíclicos aromáticos, y otras materias, pero también tiene una desventaja, que es de ser más sensible a oxidación que el combustible diesel, originado del petróleo. La oxidación influye en el incremento de acidez del combustible (causa la corrosión en el sistema de combustible) y forma un sedimento insoluble, con lo que se incrementa la viscosidad del mismo. Para incrementar la estabilidad del biodiesel originado del girasol de alto contenido oleico en cuanto a la oxidación, durante el almacenamiento y transporte, en esta investigación íbamos añadiendo diferentes porcentajes [0,01%, 0,02%, 0,05%, 0,1%, y 0,2%] de harina de maíz, infectado por micotoxinas, y por lo tanto inútil para la alimentación humana, como antioxidante natural. La influencia antioxidante iba incrementándose con la concentración hasta un óptimo nivel. Por encima de ese nivel, la influencia antioxidante iba incrementándose muy poco. La estabilidad oxidativa del biodiesel, es determinada mediante la utilización paralela de dos métodos, la prueba de Schaal en el horno (a 70ucción, obtenidos por el Método de Rancimat, tenían los valores semejantes a los obtenidos por la prueba en horno. La mayor influencia protectiva fue reportada en las muestras que contenían 0.1% de antioxidantes adicionales. RÉSUMÉ Le biodiesel en tant que combustible diesel alternatif obtenu par transestérification de gras et d’huiles végétaux avec utilisation d’alcool en présence d’un catalyseur a quelques avantages comme par exemple des émissions réduites d’hydrocarbures non brûlés, de carbone monoxyde, de sulfates, d’hydrocarbures aromatiques polycycliques et autres matières, mais son inconvénient est qu’il est plus sujet à l’oxydation que le combustible diesel à base de pétrole et qu’il peut rendre le combustible acide (causer la corrosion du système combustible) et former une couche insoluble et ainsi augmenter sa viscosité. Dans le but d’augmenter la stabilité du biodiesel à base de tournesol à haute teneur d’acide oléique contre le processus d’oxydation au cours de l’entreposage et de la distribution, différents pourcentages [0,01%, 0,02%, 0,05%, 0,1% et 0,2% (w/v)] de farine de maïs contaminée par des mycotoxines et donc impropre à la consommation humaine, ont été ajoutés comme antioxydants naturels. Avec la concentration, l’effet antioxydant a augmenté jusqu’à un niveau optimal. Au-dessus du niveau optimal, l’effet antioxydant a très peu augmenté. La stabilité oxydative du biodiesel a été déterminée à l’aide de deux méthodes parallèles, le test Schall au four (à 70oC) et la méthode Rancimat (à 110oC). Les temps d’induction obtenus par la méthode Rancimat ont été semblables aux valeurs obtenues par le test au four. Le plus grand effet de protection a été observé chez les échantillons contenant 0,1% (w/v) d’antioxydants ajoutés.

The effect of biodiesel oxidation on engine performance and emissions

Biodiesel is an alternative fuel consisting of the alkyl monoesters of fatty acids from vegetable oils or animal fats. Previous research has shown that biodiesel-fueled engines produce less carbon monoxide, unburned hydrocarbons, and particulate emissions compared to diesel fuel. One drawback of biodiesel is that it is more prone to oxidation than petroleum-based diesel fuel. In its advanced stages, this oxidation can cause the fuel to become acidic and to form insoluble gums and sediments that can plug fuel filters. The objective of this study was to evaluate the impact of oxidized biodiesel on engine performance and emissions. A John Deere 4276T turbocharged DI diesel engine was fueled with oxidized and unoxidized biodiesel and the performance and emissions were compared with No. 2 diesel fuel. The neat biodiesels, 20% blends, and the base fuel (No. 2 diesel) were tested at two different loads (100 and 20%) and three injection timings (3° advanced, standard; 3° retarded). The tests were performed at steady-state conditions at a single engine speed of 1400 rpm. The engine performance of the neat biodiesels and their blends was similar to that of No. 2 diesel fuel with the same thermal efficiency, but higher fuel consumption. Compared with unoxidized biodiesel, oxidized neat biodiesel produced 15 and 16% lower exhaust carbon monoxide and hydrocarbons, respectively. No statistically significant difference was found between the oxides of nitrogen and smoke emissions from oxidized and unoxidized biodiesel.

THE REACTION OF 3-METHYL INDOLE WITH para-ETHYLBENZENE SULFONIC ACID: FUEL INCOMPATIBILTY REACTIONS

ABSTRACT Polar Heteroatomic species have been correlated with incompatibility reactions in middle distillate fuels. Instability is defined as the formation of filterable sediments and fuel insoluble gums. Heteroatoms (oxygen, nitrogen and sulfur) have been found to be greatly enriched in such sediments. Trace levels of certain organo-sulfur compounds, especially sulfonic acids in model fuel systems, have been found to significantly increase deposit formation. The effectiveness of organic amines as additives suggests that acid/base chemistry is also involved in the formation of deposits. This paper reports on a study of p-ethylbenzene sulfonic acid reacting with 3-methyl indole in model systems. A possible reaction mechanism and a proposed structure for the product is reported. The results of the model system are contrasted to results from previous actual fuel systems.

Liquid phase oxidation of organo-sulfur compounds by tert-butyl hydroperoxide and fuel instability reactions

Polar heteroatomic species have been correlated with storage instability problems in both petroleum and shale derived middle distillate fuels. Instability is defined as the formation of filterable sediments and fuel insoluble gums. Heteroatoms (oxygen, nitrogen and sulfur) have been found to be greatly enhanced in such sediments. Trace levels of certain organo-sulfur compounds, especially sulfonic acids, have been found to significantly alter the deposit formation process. Hydroperoxides have also been implicated in the instability process which would point to free radical mechanisms. The effectiveness of organic amines as additives suggests that acid-base chemistry is also involved in the formation of deposits. This paper reports on a study of organo-sulfur, nitrogen and hydroperoxide compounds employed as dopants in fuels. The most detrimental dopant species were sulfonic acids.

CHEMICAL FACTORS AFFECTING INSOLUBLES FORMATION IN SHALE DERIVED DIESEL FUEL

ABSTRACT Detrimental changes in fuel properties with time have been a continuing problem in the use of middle distillate fuels. Instability of diesel fuels is usually defined by the formation of insoluble sediments and gums. Gravimetric stability tests have been conducted at 43° and 80°C, respectively, using three model nitrogen heterocycles, 2-methylpyridine, 2,6-di methyl quinoline, and dodecahydrocarbazole, as dopants in an otherwise stable shale diesel fuel. Potential interactive effects have been defined for these three model nitrogen heterocycles in the stable fuel in the presence of a second model dopant, t-butyl hydroperoxide. 2-Methyl pyridine and 2,6-dimethyl quinoline were inactive and only 2-methyl pyridine showed slight positive interactive effects. Dodecahydro-carbazole formed large amounts of insolubles by itself and exhibited positive interactive effects.

Shale Oil Denitrogenation with Ion Exchange

Abstract The nitrogen-containing aromatics normally found in crude retorted shale oils have been shown to be involved in reactions leading to the deposition of insoluble gums and sediments. These nitrogen-containing compounds must be removed in order to permit the effective utilization of the shale oil product. A process is proposed in which the nitrogen-containing compounds found in raw shale oil are removed by mild hydrodenitrogenation followed by resin ion exchange. Ion exchange data from experimentation involving six jet fuel (15M-271°C) and diesel fuel (271–343°C) boiling point cuts are presented. Amberlyst A-15, a macroreticular, strongly acidic, cation exchange resin is used in this study. Three types of experiments were performed: batch sorption equilibrium experiments, batch sorption kinetics experiments, and dynamic ion-exchange column performance tests. The Langmuir isotherm was found to describe the equilibrium sorption behavior of the shale oil/ion-exchange resin system fairly Well. The sorpt...

Accelerated oxidation of diesel distillate: Infrared spectra of soluble and insoluble gums

An infrared spectroscopic study of some products associated with petroleum diesel distillate instability is described. Spectra of soluble and insoluble gums which formed in the fuels during accelerated and ambient ageing are compared. The results indicate that gums derived from accelerated ageing are not the same as those which form during ambient storage. Spectral features relating to the chemical structures of gum components are discussed.

Method for the Extraction of Light Filth from Plant Gums

Abstract A new method has been developed for the extraction of extraneous materials from plant gums. Hydrochloric acid and autoclaving are used to break down and disperse partially insoluble gums, followed by sieving and extracting using a trap flask. Collaborative studies gave reproducible recoveries of rodent hairs and insect fragments, and the method is recommended for adoption as official first action.

Effect of Composition and Storage on the Properties of Jet Fuels.

Total and insoluble gum were measured in four jet fuels which had been in desert storage in steel drums for four years. A straight run fuel was the most stable, thermally cracked fuel was the least stable, and catalytically cracked fuel was intermediate in stability. In a laboratory study of stability, gas oils were treated in various ways, including hydrogenation, acid or caustic washing, and redistillation, then blended with a stable gasoline to make a simulated jet fuel and stored at 43.3/sup 0/C (110/sup 0/F) for six months in the presence of excess air. While all the treatments improved the stability, acid treatment and hydrogenation gave the most improvement. Increasing the amount of oxygen over the fuel during storage increased the amount of gum formed. A small laboratory apparatus for measuring filterability of jet fuels was developed. There was no correlation between filter-plugging tendency and insoluble gum content of a fuel. The insoluble gums were examined with an electron microscope, and it was found that filterability behavior was related to the character of the deposit. An amorphous type deposit rapidly plugged the filter, while a crystalline type deposit did not.