Biodiesel production by esterification of oleic acid with short-chain alcohols under ultrasonic irradiation condition

Author

Hoang Duc Hanh, Nguyen The Dong, Kenji Okitsu, Rokuro Nishimura and Yasuaki Maeda

Renewable Energy, 2009, vol. 34, issue 3, pages 780-783

Abstract: Production of fatty acid ethyl ester (FAEE) from oleic acid (FFA) with short-chain alcohols (ethanol, propanol, and butanol) under ultrasonic irradiation was investigated in this work. Batch esterification of oleic acid was carried out to study the effect of: test temperatures of 10–60°C, molar ratios of alcohol to oleic acid of 1:1–10:1, quantity of catalysts of 0.5–10% (wt of sulfuric acid/wt of oleic acid) and irradiation times of 10h. The optimum condition for the esterification process was molar ratio of alcohol to oleic acid at 3:1 with 5wt% of H2SO4 at 60°C with an irradiation time of 2h.

Keywords: Oleic acid; Ultrasound; Biodiesel; Esterification (search for similar items in EconPapers)
Date: 2009
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Fatty acid methyl ester synthesis catalyzed by solid superacid catalyst /ZrO2-TiO2/La3+

Author

Yan Li, Xiao-Dong Zhang, Li Sun, Jie Zhang and Hai-Peng Xu

Applied Energy, 2010, vol. 87, issue 1, pages 156-159

Abstract: A new type of solid superacid catalyst with the composition of /ZrO2-TiO2 loaded with lanthanum was prepared by precipitation and impregnation. The catalytic performance for the synthesis of fatty acid methyl ester from fatty acid and methanol was investigated. The influences of preparation conditions on catalyst performance were studied, the optimum results of which showed that amount of La(NO3)3 was 0.1 wt.%, the concentration of H2SO4 for impregnation was 0.5 mol l-1 and calcination temperature was 550 °C. In addition, the effects of reaction parameters on esterification efficiency were also studied. With the catalyst amount of 5 wt.%, methanol amount of 1 ml/g fatty acid (FA) and reaction duration of 5 h at 60 °C, the conversion ratio could reach above 95%. The catalyst recycled without any treatments could exhibit high activity with the conversion efficiency of above 90% after being reused five times.

Keywords: Superacid; Fatty; acid; Esterification; FAME (search for similar items in EconPapers)
Date: 2010
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Fuel Characteristics of Biodiesel Produced from a High-Acid Oil from Soybean Soapstock by Supercritical-Methanol Transesterification

Author

Cherng-Yuan Lin (lin7108@ntou.edu.tw) and Yi-Wei Lin (m94660002@ntou.edu.tw)
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Energies, 2012, vol. 5, issue 7, pages 1-11

Abstract: A supercritical methanol transesterification method was applied to produce biodiesel from the high-acid oil of soybean soapstock. The fuel properties of biodiesel produced with various molar ratios of methanol to raw oil were analyzed and compared in this experimental study. Oleic acid (C18:1), linoleic acid (C18:2), and palmitic acid (C16:0) were the three main compounds in the high-acid oil-biodiesel. The saturated fatty acid content of the high-acid oil increased significantly due to the supercritical-methanol transesterification reaction. The fuel characteristics of the resulting high-acid oil, including the specific gravity and kinematic viscosity, were also greatly improved. The saturated fatty acid content of the biodiesel produced from the high-acid oil was higher than that of biodiesel from waste cooking oil produced by the subcritical transesterification using a strongly alkaline catalyst. The high-acid oil-biodiesel that was produced with a molar ratio of methanol to raw oil of 42 had the best fuel properties, including a higher distillation temperature and cetane index and a lower kinematic viscosity and water content, among the biodiesels with different molar ratios.

Keywords: biodiesel; high-acid oil; saturated fatty acids; supercritical-methanol transesterification (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2012
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Enhanced triacylglyceride extraction from microalgae using free nitrous acid pre-treatment

Author

Xue Bai, Peer M. Schenk, Zhiguo Yuan, Paul A. Lant and Steven Pratt

Applied Energy, 2015, vol. 154, issue C, pages 183-189

Abstract: Triacylglyceride (TAG) recovery from algal biomass is primarily limited by the rigid algal cell envelope (cell wall and cell membrane). In this work, the effect of free nitrous acid (FNA) pre-treatment on TAG recovery from algal biomass with six different FNA concentrations is reported. Results show that at a range of low FNA concentrations (0.24–2.25mgHNO2–NL−1) TAG recovery was strongly enhanced with increasing FNA concentration. An FNA concentration of around 2mgHNO2–NL−1 resulted in a 3.3-fold increase in fatty acid recovery over untreated algae, but higher FNA concentrations (13.49 and 26.98mgHNO2–NL−1) were detrimental to TAG recovery. Analysis of the fatty acid profile revealed that the higher FNA concentrations caused a reduction in polyunsaturated fatty acids. Also, the ratio of extracted fatty acids to total lipids was significantly reduced when high FNA concentration were applied, and only non-fatty acid lipids potentially benefited from more intense FNA pre-treatments.

Keywords: Biodiesel; Fatty acid; Free nitrous acid; Microalgae; Triacylglyceride (search for similar items in EconPapers)
Date: 2015
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Catalyst-free microwave-assisted conversion of free fatty acids in triglyceride feedstocks with high acid content

Author

Jeroen Geuens, Sergey Sergeyev, Bert U.W. Maes and Serge M.F. Tavernier

Renewable Energy, 2014, vol. 68, issue C, pages 524-528

Abstract: The catalyst-free microwave-assisted conversion of free fatty acids (FFA) to alkyl esters in triglyceride feedstocks with a high acid content was studied. To this end, esterification of FFA with higher alcohols was investigated using the response surface modelling approach (RSM). A model was constructed using stearic acid and 1-butanol. The influence of reaction temperature and the FFA content in the triglyceride feedstock were studied by varying both parameters on 5 levels between 175 °C and 275 °C, and 30 mass% and 100 mass% FFA respectively. Afterwards, the general applicability of the model was verified using other FFA, fatty acid distillates (FAD) from industry and other alcohols. When using other FFA, FAD or primary alcohols other than 1-butanol, the model is able to accurately predict the actual conversion with a typical deviation between actual and predicted data of 2%. After 1 h of reaction at temperatures above 250 °C, conversions over 90% were reached.

Keywords: Free fatty acid (FFA); Esterification; Fatty acid butyl esters (FABE); Catalyst-free (search for similar items in EconPapers)
Date: 2014
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Oil palm trunk and sugarcane bagasse derived heterogeneous acid catalysts for production of fatty acid methyl esters

Author

Francis Ezebor, Melati Khairuddean, Ahmad Zuhairi Abdullah and Peng Lim Boey

Energy, 2014, vol. 70, issue C, pages 493-503

Abstract: In this study, new catalysts were prepared from oil palm trunk (OPT) and sugarcane bagasse (SCB), which are available in enormous quantities. Effect of carbonization time with statistical validation, effect of reaction variables such as catalyst loading, methanol molar ratio, reaction time, alcohol selectivity, effect of grafting Keggin anions onto the multifunctional catalyst and composition of the biomasses were investigated. Under optimum conditions, the OPT and SCB catalysts afforded 88.8% and 96% yield of methyl palmitate, respectively. From statistical analysis, P-value (prob. > F) for OPT indicates that difference between the means of different carbonizations is not significant, but it is significant for SCB 4 h and 8 h carbonizations. In synthesis of ethyl palmitate and butyl palmitate, OPT catalyst gave FAME yield of 86.7% and 88% respectively, while SCB catalyst gave 90.7% and 91.6%, respectively. Grafting of Keggin anions by incipient wetness impregnation resulted in 3.6% increase in FAME yield, which shows that very few active sites consisting of Keggin anions and lacunary Keggin anions have been introduced. The catalysts are recyclable, and showed only 10.5–12.5% loss in activity after six cycles of repeated use. The catalysts are highly suitable for biodiesel production.

Keywords: Oil palm trunk; Sugarcane bagasse; Heterogeneous acid catalysts; Phosphotungstic acid impregnation; Completely randomized design; Biodiesel (search for similar items in EconPapers)
Date: 2014
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Preparation of Y-Alumina from Kankara Kaolin in Nigeria by Acid Leaching Using Hydrochloric Acid

Author

A. Aliyu, U. Ahmadu, A. A. Abdelmalik and U. Sadiq
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Academic Journal Chemistry, 2016, vol. 1, issue 1, pages 8-12

Abstract: Investigation has been done concerning Kaolin based alumina prepared by acid leaching method. This was initially fired at 600? for 4 hours to increase its reactivity. For better yield Hydrochloric Acid ( HCl) was used for the digestion as against the conventional Sulphuric acid (H2SO4). The gelatinous precipitate of the hydrated alumina was further filtered under vacuum 400°C for 2h, which resulted the formation of ?-alumina. The structure of ?-alumina was confirmed by XRD and its corresponding diffractogram parameters and SEM and the mean particles size of ?-alumina was determined by SEM to be 3 - 9 ?m.. Foamy agglomerates at low magnification and the presence of larger voids in theirs structures at high magnification were visible from the SEM images. The study revealed that kaolin could be promising material for preparation of ?-alumina

Keywords: kaolin; Acid leaching; XRD; Nanoscale; Digestion. (search for similar items in EconPapers)
Date: 2016
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Networks in Amino Acids Based on Mutation

Author

Adil Akhtar and Tazid Ali

Studies in Microeconomics, 2015, vol. 3, issue 2, pages 89-100

Abstract: Abstract Network theory has a broad spectrum of application including biological science. In the present study, we have analyzed hydrophobic and hydrophilic amino acids’ network based on mutation. To analyze the relative importance of the amino acids, we have discussed different measures of centrality and investigated the correlation coefficients between these measures. We have also dealt with clustering coefficient. Finally, we have discussed the degree of distribution as well as skewness for the networks.

Keywords: Amino acid; centrality measure; clustering coefficient; degree of distribution (search for similar items in EconPapers)
Date: 2015
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The production of acetic acid from microalgae under hydrothermal conditions

Author

Zheng Shen, Jingfei Zhou, Xuefei Zhou and Yalei Zhang

Applied Energy, 2011, vol. 88, issue 10, pages 3444-3447

Abstract: Microalgae for carbon dioxide mitigation was applied to the production of acetic acid under hydrothermal conditions with H2O2 oxidant. Results showed that acetic acid was obtained with a good yield of 14.9% based on a carbon base at 300°C for 80s with 100% H2O2 supply. This result should be helpful to facilitate studies for developing a new green and sustainable process in order to produce acetic acid from microalgae, which are the fastest growing sunlight-driven cell factories. These results show that it is possible to develop a process for conversion of microalgae biomass into acetic acid.

Keywords: Microalgae; Hydrothermal process; Acetic acid (search for similar items in EconPapers)
Date: 2011
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Evaluation of the effect of the dilute acid hydrolysis on sugars release from olive prunings

Author

Juan F. García Martín, Sebastián Sánchez and Manuel Cuevas

Renewable Energy, 2013, vol. 51, issue C, pages 382-387

Abstract: Olive prunings are considered a potential lignocellulosic raw material for production of energy (fuel-ethanol, pellets...) and other value-added products as an alternative to starch-containing feedstock. From an economic point of view, it is particularly important to recover sugars from hemicellulose. The use of dilute acid can lead to rapid hydrolysis conditions, providing hydrolysates rich in d-glucose and d-xylose that do not require further treatment. The effect of the residence time, temperature and sulphuric acid concentration on the formation of d-glucose and d-xylose was estimated by response surface methodology. Batch hydrolysis was carried out at very low temperatures (70–90 °C) and H2SO4 concentrations from 0 to 1 N, sampling at different times from 0 to 300 min. According to statistical analysis, all of the three parameters had significant interaction effects on sugars production. Results illustrated that the highest concentrations of d-glucose and d-xylose were found at the highest levels of temperature, acid concentration and residence time assayed. In these conditions, the maximum predicted yields expressed as g of sugar per 100 g of dry matter fed were 0.13 in d-glucose (about 40% of maximum attainable) and 0.10 in d-xylose (about 60% of the potential yield).

Keywords: Acid hydrolysis; d-glucose; Olive prunings; Sulphuric acid; d-xylose (search for similar items in EconPapers)
Date: 2013
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Biodiesel production via esterification of oleic acid catalyzed by chlorosulfonic acid modified zirconia

Author

Yue Zhang, Wing-Tak Wong and Ka-Fu Yung

Applied Energy, 2014, vol. 116, issue C, pages 191-198

Abstract: Biodiesel is a promising renewable alternative to fossil energy. Biodiesel production from low-cost feedstock involves an essential pretreatment step – esterification of free fatty acids (e.g. oleic acid), for avoiding soap formation and catalyst deactivation. Sulfuric acid modified zirconia (H2SO4–ZrO2) is known to be an effective heterogeneous catalyst for this reaction. However, due to rapid SO42- leaching, its reusability is low and its practical use is thus largely hindered. Herein, we report a more stable solid acid analogue for the reaction, chlorosulfonic acid modified zirconia (HClSO3–ZrO2). It was characterized by XRD, SEM, BET, EDX, IR, TGA, and NH3-TPD. Compared with H2SO4–ZrO2, there is over 3 times more sulfur content and nearly 4 times more acid sites amount for HClSO3–ZrO2. More importantly, HClSO3–ZrO2 demonstrates high catalytic activity and long durability in esterification of oleic acid, in which the fatty acid methyl ester yield reaches 100% consecutively for at least 5 cycles under mild conditions.

Keywords: Biodiesel; Free fatty acid; Oleic acid esterification; Sulfated zirconia; Chlorosulfonic acid (search for similar items in EconPapers)
Date: 2014
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Esterification of fatty acids using acid-activated Brazilian smectite natural clay as a catalyst

Author

Michelle J.C. Rezende and Angelo C. Pinto

Renewable Energy, 2016, vol. 92, issue C, pages 171-177

Abstract: This work reports the use of an acid-activated Brazilian smectite natural clay-based catalyst in the esterification of fatty acids at atmospheric pressure and without a co-solvent. Conversion levels of 99%, 98%, 93% and 80% were reached for caprylic, lauric, stearic and oleic methyl esters, respectively, using 1:3 fatty acid/methanol molar ratio, heating bath at 100 °C after 4 h. A conversion level of 89% was achieved for methyl esters from a fatty acid residue of the palm oil refining industry in the same reaction condition. The acid-activated clay provided better performance than the commercial catalyst K-10. The effects of catalyst amount, temperature, fatty acid/alcohol molar ratio and time were investigated. The heating activation of the catalyst immediately before the catalytic test increased the conversion from 94% to 99% using 1:1.5 stearic acid/methanol molar ratio, heating bath at 100 °C after 4 h. The catalyst was reused five times. The conversion decreases less than 5% in the first three reuses. The smectite natural clay and the catalyst were characterized by X-ray fluorescence, X-ray diffraction, n-butylamine thermodesorption, nitrogen adsorption analysis, thermogravimetric analysis and differential thermal analysis.

Keywords: Biodiesel; Clay; Fatty acid esterification (search for similar items in EconPapers)
Date: 2016
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Development of amino acid and amino acid-complex based solid sorbents for CO2 capture

Author

Bingbing Jiang, Xianfeng Wang, McMahan L. Gray, Yuhua Duan, David Luebke and Bingyun Li

Applied Energy, 2013, vol. 109, issue C, pages 112-118

Abstract: For the first time, amino acid (AA) and AA-complex based solid sorbents for CO2 removal were investigated by immobilizing AAs and AA-complexes into porous polymethylmethacrylate (PMMA) microspheres. Deposition of pure AAs into porous PMMA supports led to limited CO2 adsorption in sorbents, because large AA particles or crystals were formed during deposition of pure AAs into PMMA microspheres and some pores of the PMMA microspheres were clogged. Among the AA sorbents studied, Arginine (Arg) solid sorbents had the highest CO2 adsorption capacity. Interestingly, by forming AA-complexes with other polymers, we substantially improved AA water solubility, achieved uniform immobilization of AAs inside PMMA microspheres, and obtained high CO2 adsorption capacity. We found that the types of AA-complexes, complex loading capacity, and ratio of AAs in the complexes could have significant effects on CO2 adsorption properties. Especially, complexing Arg with a strong polyelectrolyte (i.e. polystyrene sulfonate) resulted in substantially improved AA water solubility and high CO2 adsorption capacity. Our developed AA-complex based solid sorbents could be innovative since they could eliminate concerns related to potential equipment corrosion as well as high heat duty associated with aqueous solvent regeneration all the while retaining the advantageous properties (high thermal stability, excellent biocompatibility, and negligible volatility) of AAs.

Keywords: CO2 removal; Amino acid; Amino acid-complex; Solid sorbent; Immobilization (search for similar items in EconPapers)
Date: 2013
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Solid superacid catalyzed fatty acid methyl esters production from acid oil

Author

Yan Li, Xiao-Dong Zhang, Li Sun, Min Xu, Wen-Guang Zhou and Xiao-Hui Liang

Applied Energy, 2010, vol. 87, issue 7, pages 2369-2373

Abstract: A solid superacid catalyst was evaluated for the production of fatty acid methyl esters (FAMEs) from acid oil containing about 60 wt.% free fatty acids. It was demonstrated that /ZrO2-TiO2/La3+ was an effective catalyst for simultaneous transesterification and esterification. The optimization of reaction parameters was performed, showing that maximum yield of above 90% could be obtained under the conditions that molar ratio of alcohol/oil was 15:1, catalyst amount was 5 wt.%, temperature was 200 °C and duration was 2 h. The catalyst was finally recycled and utilized for five times repeatedly with little loss in activity. The final products purified by molecular distillation were detected by GC-MS. The content of FAMEs reached 96.24%.

Keywords: Solid; superacid; catalyst; Fatty; acid; methyl; esters; Acid; oil (search for similar items in EconPapers)
Date: 2010
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Understanding conserved amino acids in proteins

Author

Nikolay V. Dokholyan, Leonid A. Mirny and Eugene I. Shakhnovich

Physica A: Statistical Mechanics and its Applications, 2002, vol. 314, issue 1, pages 600-606

Abstract: It has been conjectured that evolution exerted pressure to preserve amino acids bearing thermodynamic, kinetic, and functional roles. In this letter we show that the physical requirement to maintain protein stability gives rise to a sequence conservatism pattern that is in remarkable agreement with that found in natural proteins. Based on the physical properties of amino acids, we propose a model of evolution that explains conserved amino acids across protein families sharing the same fold.

Keywords: Protein evolution; Conserved amino acids; Model (search for similar items in EconPapers)
Date: 2002
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The impact of acid rain on China’s socioeconomic vulnerability

Author

Yue-Jun Zhang (zyjmis@126.com) and Hao-Ran Chang

Natural Hazards: Journal of the International Society for the Prevention and Mitigation of Natural Hazards, 2012, vol. 64, issue 2, pages 1671-1683

Abstract: Acid rain has been a great threat to socioeconomic sustainable development of China; therefore, we develop an indicator system based on the sensitivity and adaptive capacity perspectives and employ the TOPSIS (Technique for Order Preference by Similarity to Ideal Solution) approach to investigate the impact of acid rain on socioeconomic vulnerability of China. Some empirical findings are obtained. First, there is significant provincial difference of socioeconomic vulnerability caused by acid rain in China. Specifically, Tibet, Qinghai, and Shanghai are the top three provinces with the largest vulnerability but Inner Mongolia, Xinjiang, and Jilin are bottom of the rankings. Second, adaptive capacity indicators overall appear more important than sensitivity indicators to measure the vulnerability of acid rain, and the most important indicators are population density and output value of agriculture, forestry, animal husbandry, and fishery while GDP per capita ranks the last. Third, upgrading energy structure and reducing outdated capacity in China prove to be effective means to mitigate vulnerability of acid rain, which has been validated in Guizhou and Hunan provinces. Finally, great attention should be attached to the population increase so as to curb the acid rain vulnerability, especially in Beijing and Tianjin. These results present a basis for future acid rain prevention planning and economic development in China. Copyright Springer Science+Business Media B.V. 2012

Keywords: Acid rain; Vulnerability; TOPSIS; China (search for similar items in EconPapers)
Date: 2012
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