Improved Oxidative Stability in Biodiesel via Commercially-Viable Processing Strategies

Biodiesel made from waste cooking oil (WCO) frequently requires antioxidants to meet oxidation stability specifications set forth in ASTM D6751 or EN 14214. In contrast, unrefined cottonseed oil (CSO), containing tocopherols and high concentrations of gossypol, a toxic polyphenolic antioxidant, is unique for biodiesel processing because it produces biodiesel resulting in higher oxidation stability. During biodiesel production, however, only a portion of these endogenous natural antioxidants are suspected to be retained. Because the economics of biodiesel manufacturing rely upon inexpensive sources of triglycerides, emphasis was placed upon developing improved alternative commercially-viable processing strategies where WCO is the main source of methyl esters (WCOME) and CSO is used as a supplemental source of triglycerides and antioxidants in a 4:1 ratio. This study compares four commercially-viable processing methods which attempt to increase the oxidation stability of WCO:CSO biodiesel. The measurement of the many endogenous antioxidant concentrations in the finished biodiesel was not performed; instead, the induction period (IP) was used to measure the bulk oxidative stability increase of the finished biodiesel. The novel processing strategies developed for this study utilize the solvent properties of fatty acid methyl esters and glycerol and are sustainable because they avoid additional chemical inventory for the biodiesel processor. This study concludes that two new processing strategies, a \u27reduced glycerol process\u27 or an \u27extraction process\u27, resulted in a biodiesel product that had statistically significant improved oxidation stability when compared to common processing strategies, a \u27mixed oil process\u27 or a \u27separate oil process\u27. Another significant finding is that high shear homogenization during transesterification reduced reaction time from the published typical one hour to 16 minutes

OPTIMIZATION OF BIODIESEL PRODUCTION FROM CRUDE COTTONSEED OIL AND WASTE VEGETABLE OIL:CONVENTIONAL AND ULTRASONIC IRRADIATION METHODS

Biodiesel, derived from the transesterification of vegetable oils or animal fats with simple alcohols, has attracted more and more attention recently. As a cleaner burning diesel alternative, biodiesel has many attractive features including: biodegradability, nontoxicity, renewability and low emission profiles. Although cottonseed oil was the first commercial cooking oil in the U.S, it has progressively lost its market share to some vegetable oils that have larger production and less cost. However, regarding the active researches on biodiesel production from vegetable oils, there is a promising prospective for the cottonseed oil as a feedstock for biodiesel production, which may enhance the viability of the cottonseed industry. The focus of this research is to optimize the biodiesel production from crude cottonseed oil. The effect of variables including methanol/oil molar ratio, catalyst concentration, reaction time, reaction temperature, and rate of mixing on the biodiesel yield was examined and optimized by response surface methodology (RSM). Besides, a second-order model was deduced to predict the biodiesel yield. Confirmation experiment was further conducted, validating the efficacy of the model. In addition to conventional transesterificaiton method, low frequency ultrasonic irradiation was also investigated for biodiesel production. This study demonstrated that the ultrasound treatment was more efficient in biodiesel production than the conventional method. This was attributed to the ultrasound effect, which can make methanol to cavitate so as to disperse the oil phase into nano-droplets and form a fine emulsion ofmethanol in oil. As a result, contact surface between the reagents is dramatically increased resulting in a significant increase of the reaction speed. Moreover, engine performance test of the cottonseed oil biodiesel (cottonseed oil methyl esters, COME) was examined. The results showed that CO, CO2 and NOx emissions of the COME were lower than those of the No. 2 diesel fuel, although there was no significant difference at the statistical level of p\u3c0.05. The engine test also demonstrated a slightly higher amount of consumption and less tendency of coke formation from the COME than those from the No. 2 diesel fuel. In general, the cottonseed oil biodiesel exhibited friendly environmental benefits and acceptable stability, demonstrating its feasibility as an alternative fuel

Biodiesel production processes and sustainable raw materials

Energy security and environmental concerns, related to the increasing carbon emissions, have prompted in the last years the search for renewable and sustainable fuels. Biodiesel, a mixture of fatty acids alkyl esters shows properties, which make it a feasible substitute for fossil diesel. Biodiesel can be produced using different processes and different raw materials. The most common, first generation, biodiesel is produced by methanolysis of vegetable oils using basic or acid homogeneous catalysts. The use of vegetable oils for biodiesel production raises serious questions about biodiesel sustainability. Used cooking oils and animal fats can replace the vegetable oils in biodiesel production thus allowing to produce a more sustainable biofuel. Moreover, methanol can be replaced by ethanol being totally renewable since it can be produced by biomass fermentation. The substitution of homogeneous catalyzed processes, nowadays used in the biodiesel industry, by heterogeneous ones can contribute to improve the biodiesel sustainability with simultaneous cost reduction. From the existing literature on biodiesel production, it stands out that several strategies can be adopted to improve the sustainability of biodiesel. A literature review is presented to underline the strategies allowing to improve the biodiesel sustainability.info:eu-repo/semantics/publishedVersio

Valorization of Wastes for Biodiesel Production: The Brazilian Case

This chapter intends to bring an overview about the Brazilian researches and their contributions to the production of biodiesel from wastes. Currently, the main obstacles to spread the use of biodiesel are its high cost of production and the competition between biodiesel and food industries. So, the use of wastes plays an important role in reducing the biodiesel costs and reusing the materials that have no other applications, as deodorization residues, neutralization soap sticks, and animal fats, among others. Then, we present a review about Brazilian studies involving waste oils and fatty–acid-rich raw materials that helped the advancement in this field of knowledge during the last few years

Tertiary butylhydroquinone influence over oxidation stability of biodiesel from waste cooking oil

ABSTRACTAn oxidation stability is very important for a long-term storage of biodiesel. Some physical (density and viscosity) and chemical properties (acid value, iodine value, and peroxide value) were analyzed to predict the oxidation stability for biodiesel produced from Waste Cooking Oil (WCO). WCO is one of the potential feedstocks in Indonesia, which is a large cooking oil consumer. Biodiesel from WCO was produced by transesterification process in 60 oC temperature for one hour reaction time. Methanol was added in 4:1 (v/v) ratio of WCO with 2% potassium hydroxide as a catalyst. This study observed the influence of tertiary butylhydroquinone (TBHQ), a synthetic antioxidant, on  the oxidation stability of biodiesel. TBHQ was used as an antioxidant agent to prevent biodiesel oxidation for such long-term storage. It was blended with biodiesel at various concentrations (0-1200 ppm). Samples were taken every week to measure the density, viscosity, acid value, iodine value (IV) and peroxide value (PV) during the storage process of the biodiesel blends which was conducted for 4 weeks. The experimental results revealed that an improvement in oxidation stability was achieved in all TBHQ concentrations. All parameters meet Indonesia’s National Standards (SNI) for biodiesel added with TBHQ up to 1200 ppm. Biodiesel which was treated with 1200 ppm of TBHQ provided the best result, due to its density, viscosity, IV, and PV.  However, TBHQ addition was did not affect the free fatty acid and acid number for 4 weeks of storage.Keywords: antioxidant; biodiesel; oxidation stability; waste cooking oilABSTRAKKetahanan oksidasi merupakan karakteristik yang sangat penting dalam penyimpanan biodiesel. Penelitian ini menganalisis sifat-sifat fisis (densitas dan viskositas) serta sifat-sifat kimia (angka asam, angka iod dan angka peroksida) biodiesel minyak jelantah untuk memperkirakan ketahanannya terhadap pengaruh oksidasi. Minyak jelantah merupakan salah satu bahan baku biodiesel yang sangat potensial di Indonesia, karena kapasitas penggunaannya yang cukup besar. Biodiesel minyak jelantah dihasilkan dengan transesterifikasi pada suhu 60 oC selama 1 jam. Metanol yang ditambahkan dalam reaksi ini menggunakan perbandingan volume 4:1, dengan katalis KOH sebanyak 2% berat minyak. Penelitian ini mempelajari pengaruh tertiary butylhydroquinone (TBHQ) terhadap ketahanan oksidasi biodiesel minyak jelantah. TBHQ digunakan sebagai antioksidan dalam penyimpanan biodiesel jangka panjang. TBHQ dicampurkan ke dalam biodiesel dengan variasi konsentrasi 0-1200 ppm. Ketahanan oksidasi dipelajari selama masa simpan 4 minggu. Sampel dianalisis densitas, viskositas, angka asam, angka iod dan angka peroksida setiap minggu. Hasil analisis menunjukkan bahwa ketahanan oksidasi biodiesel minyak jelantah telah memenuhi SNI pada semua konsentrasi TBHQ. Hasil terbaik diberikan oleh biodiesel jelantah yang ditambahkan 1200 ppm TBHQ, menilik dari nilai densitas, viskositas, angka peroksida dan bilangan iod. Penambahan TBHQ tidak berpengaruh secara signifikan terhadap nilai asam lemak bebas dan angka asam selama penyimpanan 4 minggu.Kata kunci: biodiesel, ketahanan oksidasi, antioksidan, minyak jelanta

Potential valorization of waste cooking oils into sustainable bio-lubricants

This work explores the feasibility of using waste cooking oils (WCO) as eco-lubricants. Five WCO from different food facilities were studied. Three of them were fractionated into both lighter and heavier fractions by molecular distillation. A comprehensive chemical characterization (fatty acids distribution, polar compounds and acidity) was carried out on all WCOs and their fractions, which led to set relationships with the oils’ properties (such as viscosity index, low temperature viscous flow behavior, oxidation resistance, etc.). It is worth mentioning the high viscosity index values found in waste cooking oils with both low total polar compounds and acidity level, as well as the benefit which acidity had on their fluidity at low temperature and their lubricity. Moreover, it was also noteworthy that the lighter fractions, merely constituted by free fatty acids (FFA), presented an improved oxidative resistance. The largest OOT enhancement, 12.4%, was found for the light fraction of a non-segregated oil. Moreover, a better thermal stability was shown by the heavier fractions. Finally, both fractions exhibited enhanced friction-reducing capability as compared to their parent WCO. The light fractions from a nonsegregated oil, a fast food restaurant oil and a deep-fried food establishment oil yielded wear reductions of 11.7%, 44.3% and 36.8%, respectively. Therefore, molecular distillation has been proved to be a key strategy to obtain more efficient liquid eco-lubricants.This work explores the feasibility of using waste cooking oils (WCO) as eco-lubricants. Five WCO from different food facilities were studied. Three of them were fractionated into both lighter and heavier fractions by molecular distillation. A comprehensive chemical characterization (fatty acids distribution, polar compounds and acidity) was carried out on all WCOs and their fractions, which led to set relationships with the oils’ properties (such as viscosity index, low temperature viscous flow behavior, oxidation resistance, etc.). It is worth mentioning the high viscosity index values found in waste cooking oils with both low total polar compounds and acidity level, as well as the benefit which acidity had on their fluidity at low temperature and their lubricity. Moreover, it was also noteworthy that the lighter fractions, merely constituted by free fatty acids (FFA), presented an improved oxidative resistance. The largest OOT enhancement, 12.4%, was found for the light fraction of a non-segregated oil. Moreover, a better thermal stability was shown by the heavier fractions. Finally, both fractions exhibited enhanced friction-reducing capability as compared to their parent WCO. The light fractions from a non- segregated oil, a fast food restaurant oil and a deep-fried food establishment oil yielded wear reductions of 11.7%, 44.3% and 36.8%, respectively. Therefore, molecular distillation has been proved to be a key strategy to obtain more efficient liquid eco-lubricants.This work was supported by “Programa Operativo FEDER-Andalucía 2014–2020 from "Consejería de Economía y Conocimiento de la Junta de Andalucía” and the University of Huelva [grant numbers UHU- 1255843 and UHU-202008]. Also, the Social Innovation Chair of “Aguas de Huelva” at the University of Huelva. Funding for open access charge: Universidad de Huelva / CBUA. The authors gratefully acknowledge the recollected waste cooking oil and kindly supplied by the authorized waste manager (GRU 2066) BIOLIA

Effects of storage on the properties of rapeseed oil and alcohol blends

Received: February 1st, 2021 ; Accepted: May 2nd, 2021 ; Published: May 4th, 2021 ; Correspondence: [email protected] viscosity and density are important fuel properties because they influence fuel atomisation during injection into the engine cylinder. The viscosity and density of neat vegetable oils usually are too high to allow optimal use of these oils in compression ignition engines. Blending vegetable oils with alcohols can improve these properties, but it is not known whether the blend properties remain stable during storage. This study measured kinematic viscosity (at 40 °C), density (at 15 °C) and surface tension of rapeseed oil-alcohol blends that had been stored in closed borosilicate glass bottles at room temperature in the dark for 49 weeks. The values were compared with those of the fresh blends. Further measurements of oxidation stability for the rapeseed oil and the blends were taken after 72 weeks of storage. The blends consisted of rapeseed oil with ethanol at 5 vol–%, and rapeseed oil with 1–butanol at 5 vol–%, 10 vol–%, 20 vol–% and 30 vol–%. All in all, the observed changes during storage were small. Density values deviated by less than 1%, surface tension by no more than 3% and kinematic viscosity differed from the fresh blends’ values by 1% to 8%. Surface tension had increased in some blends and decreased in others. Kinematic viscosity rose in all blends, with the smallest increase measured for the rapeseed oil–butanol 30 vol–% blend. This blend also showed the best oxidation stability, which was close to six hours

Effects of storage on the properties of rapeseed oil and alcohol blends

Received: February 1st, 2021 ; Accepted: May 2nd, 2021 ; Published: May 4th, 2021 ; Correspondence: [email protected] viscosity and density are important fuel properties because they influence fuel atomisation during injection into the engine cylinder. The viscosity and density of neat vegetable oils usually are too high to allow optimal use of these oils in compression ignition engines. Blending vegetable oils with alcohols can improve these properties, but it is not known whether the blend properties remain stable during storage. This study measured kinematic viscosity (at 40 °C), density (at 15 °C) and surface tension of rapeseed oil-alcohol blends that had been stored in closed borosilicate glass bottles at room temperature in the dark for 49 weeks. The values were compared with those of the fresh blends. Further measurements of oxidation stability for the rapeseed oil and the blends were taken after 72 weeks of storage. The blends consisted of rapeseed oil with ethanol at 5 vol–%, and rapeseed oil with 1–butanol at 5 vol–%, 10 vol–%, 20 vol–% and 30 vol–%. All in all, the observed changes during storage were small. Density values deviated by less than 1%, surface tension by no more than 3% and kinematic viscosity differed from the fresh blends’ values by 1% to 8%. Surface tension had increased in some blends and decreased in others. Kinematic viscosity rose in all blends, with the smallest increase measured for the rapeseed oil–butanol 30 vol–% blend. This blend also showed the best oxidation stability, which was close to six hours

Development of Biodiesel Production Processes from Various Vegetable Oils

Biodiesel is an alternative fuel to petroleum diesel that is renewable and creates less harmful emissions than conventional diesel thus the use of this fuel is a shift toward “sustainable energy”. Biodiesel can be produced from vegetable oil, animal fat, and organisms such as algae or cyanobacteria. Since vegetable oils are the major source for current commercial biodiesel, they are the focus of this thesis. The main objective of this Ph.D. research is to develop processes suitable to produce biodiesel from various vegetable oils especially for those of non-edible oils such as used cooking oil, canola oil from greenseed, and mustard oil. An additional objective is to understand the relationship between the parent vegetable oils and the corresponding biodiesel properties. Used cooking oil was the first vegetable oil investigated in this research. Initially, oil degradation behavior was monitored closely during frying. During 72 hours of frying, acid value and viscosity of the oil increased from 0.2 to 1.5 mgKOH•g-1 and from 38.2 to 50.6 cP, respectively. It was found that ester yield was improved by addition of canola oil to used cooking oil, i.e. addition of 20% canola oil to used cooking oil increased methyl ester yield and ethyl ester yield by 0.5% and 12.2%, respectively. At least 60% canola oil addition is needed to produce ASTM grade ethyl ester biodiesel. The optimum reaction conditions to produce biodiesel are 1% KOH loading, 6:1 alcohol to oil ratio, 600 rpm stirring speed, and either 50°C reaction temperature for 2 hr or 60°C reaction temperature for 1.5 hr for methanolysis and 60°C reaction temperature for 2 hr for ethanolysis. Among non-edible vegetable oils, greenseed canola oil can be used in the most simple biodiesel production process. In this case, an addition of fresh vegetable oil is not required, because chlorophyll contained in this oil did not play a crucial role in the reaction activity. Methyl ester yields derived from greenseed canola oil without and with 94.1 ppm chlorophyll content are 95.7% and 94.8%, respectively. In contrast, erucic acid contained in mustard oil created difficulties in the production process. Ester yield derived from mustard oil using the conditions mentioned above was only 66% due to the present of unconverted monoglyceride. To obtain a deeper understanding on mustard oil transesterification, its reaction kinetics was studied. In the kinetic study, transesterification kinetics of palm oil was also investigated to study the effect of fatty acid chain length and degree of saturation on the rates of the reactions. It is shown in this research that the rates of mustard monoglyceride transesterification (rate constant = 0.2-0.6 L•mol-1•min-1) were slower that those of palm monoglyceride transesterification (rate constant = 1.2-4.2 L•mol-1•min-1) due to its lower molecular polarity resulting from the longer chain of erucic acid. The activation energy of the rate determining step (in this case, conversion of triglyceride to diglyceride reaction step) of mustard transesterification was, however, 26.8 kJ•mol-1, which is similar to those of other vegetable oils as reported in literature. Despite the presence of unconverted monoglyceride, distillation can be used to obtain a high purity ester. Several ester properties are determined by characteristics of the parent oil and choice of alcohol used in transesterification. Chlorophyll contained in greenseed canola oil, for example, has an adverse effect on biodiesel oxidative stability. The induction time for methyl ester derived from treated greenseed canola oil (pigment content = 1 ppm) was enhanced by 12 minutes compared to that derived from crude greenseed canola oil (pigment content = 34 ppm). The optimum bleaching process involves the use of 7.5 wt.% montmorillonite K10 at 60°C and stirring speed of 600 rpm for 30 minutes. In addition, it was found that induction time of treated greenseed canola ethyl ester (1.8 hr) was higher than that of methyl ester (0.7 hr), which suggests a better oxidative stability of esters of higher alcohols. Furthermore, the use of higher alcohols instead of methanol produced materials with improved low temperature properties. For example, the crystallization temperatures of monounsaturated methyl, ethyl, propyl, and butyl esters prepared from mustard oil were -42.5°C, -51.0°C, -51.9°C, and -58.2°C, respectively. In contrast, the lubricity of biodiesel is mainly provided by its functional group which is COOCH3 for methyl ester. The use of higher alcohols in transesterification results in a less polar functional group in the corresponding ester molecule, which leads to reduction in ester lubricity. Methyl ester provided the highest lubricity among all esters produced, i.e. wear reduction at 1% treat rate of methyl ester, ethyl ester, propyl ester, and butyl ester are 43.7%, 23.2%, 30.7% and 30.2%, respectively. The outcomes of this research have been published in several scientific journals and presented at national and international conferences. The published articles and conference presentations are listed at the beginning of each chapter in this thesis

Biodiesel Production From Waste Materials: Process Development and Performance Evaluation

World energy crisis is a definite truth, and the rising fuel price is evidence of it. Implementation of renewable energy to overcome the energy crisis is essential. The requirement of energy, especially for road transportation sector can meet through renewable energy. Biodiesel is an appropriate alternative of fossil diesel to run an internal combustion engine efficiently. Currently, vegetable oil is the predominantly accepted feedstock for biodiesel around the globe. However, it is not a feasible biodiesel feedstock due to its insufficient availability and potential food security issues. Current research work explored possible potential biodiesel feedstocks, i.e., rice mill waste, sewage sludge, and kitchen food waste. Appropriate lipid extraction process and transesterification method were developed for waste feedstocks such as rice mill waste, sewage sludge, and kitchen food waste. Reaction parameters of lipid extraction and transesterification were optimized through Taguchi optimization technique. Taguchi model improved the lipid yield by 8.5% (dry wt%) and rice bran methyl ester (RBME) yield by 4.3% (dry weight%) as compared to manually obtained maximum yield. The relevance of Taguchi model for optimization of biodiesel production was verified. Impact of raw material processing on biodiesel properties was established. Influence of co-solvent such as methyl tert butyl ether and tetrahydrofuran on transesterification of sewage sludge lipid was demonstrated through Taguchi generated plots. The present study also developed a closed vessel microwave irradiation process for rapid formation of fatty acid methyl ester (FAME) from kitchen food waste. Traditional transesterification process face difficulties with sample moisture content. But, modified microwave technique utilizes excess moisture to produce a by-product without interrupting the transesterification process. Significantly less energy consumption of 0.088 kWh per liter FAME production was measured. Maximum FAME yield of 96.89 wt% was achieved at microwave cell pressure: 2.2 MPa, temperature: 170 0C, reaction time: 4 min and catalyst concentration: 0.5 wt% with single phase blend ratio 1:6:30 (oil: co-solvent: methanol). Microwave irradiation method and conventional heating in combination with cosolvent-acid catalyzed transesterification resulted in 2.7 and 2.6 times less energy consumption, respectively than the conventional acid catalyzed transesterification process. Selection of appropriate co-solvent for modified microwave process delivered a novel transesterification byproduct glycerol tert butyl ether (GTBE) instead of traditional glycerol. This GTBE is a potential fuel additive that can boost ignition characteristics during engine analysis. Present work also developed an ultrasonic reactor for biodiesel production. The study introduced the reaction parameter kinematic viscosity that significantly eases the process and accelerates the transesterification duration maximum by 4-5 times for sample with free fatty acid (FFA) content greater than 7%. Ultrasonic irradiation in combination with co-solvent improved the reaction output (95.56%), brought down the catalyst demand and smoothened product separation process. The product separation is much easier and faster than the microwave and conventional transesterification based FAME mixture. Commercialization of this method can be done effortlessly due to the simplicity of method and ability to process a wide range of raw material (in terms of FFA content and kinematic viscosity) with minimal modification to the process. Obtained breakeven price of biodiesel is found to be less than current fossil diesel cost. Performance and emission analysis of produced biodiesel were performed to examine the fuel efficiency. Engine performance and emission properties of sewage sludge-derived biodiesel (SSB) were assessed. Major concern behind SSB implementation is the change in fuel properties with geographical and seasonal variation. However, the current study established the positive aspect of SSB. It contains low polyunsaturated fatty acid irrespective of geography and season. Specifically, fewer C18:2 and C18:3 percentages studied for worldwide SSB assures the fuel of better stability, reduced auto-oxidation, and fewer pollutant emissions. Moreover, SSB can also blend with biodiesel derived from other feedstocks with higher polyunsaturated fatty acids, resulting in reduced auto-oxidation by lowering C18:2 and C18:3 concentrations. Finally, the optimum fatty acid profile was prepared through dual biodiesel blend (biodiesel-biodiesel) to ensure enhanced fuel property for better ignition and reduced carbon monoxide (CO), hydrocarbon (HC) and nitrogen oxide (NOx) emissions. GTBE, the by-product of modified microwave irradiation process was used to prepare blend with biodiesel (GTBE-biodiesel blend). GTBE-biodiesel blend in combination with modified injection pressure resulted with higher brake thermal efficiency than fossil diesel and reported a maximum, 10.5% and 20% reduction in NOx and CO emission, respectively. GTBE as a fuel additive is economical as well as environmentally friendly as it is prepared from the dissociation of methyl term butyl ether, i.e., potentially hazardous to dispose of and banned by some countries. Multi-objective optimization on the basis of ratio analysis method (MOORA) was used to optimize fatty acid profile, GTBE-biodiesel blend proportion and injection pressure for improved engine performance and reduced emission