Comparative Analysis of Fuel Composition and Physical Properties of

Laboratory Experiment Cite This: J. Chem. Educ. XXXX, XXX, XXX−XXX

pubs.acs.org/jchemeduc

Comparative Analysis of Fuel Composition and Physical Properties of Biodiesel, Diesel, Kerosene, and Jet Fuel Timm A. Knoerzer,* Elise M. Hill, Todd A. Davis, Scott T. Iacono, Jane E. Johnson, and Gary J. Balaich Department of Chemistry, United States Air Force Academy, HQ USAFA/DFC 2355 Fairchild Drive, Suite 2N-225, USAF Academy, Colorado 80840, United States J. Chem. Educ. Downloaded from pubs.acs.org by EASTERN KENTUCKY UNIV on 08/16/18. For personal use only.

S Supporting Information *

ABSTRACT: Biodiesel is an important alternative fuel synthesized by the trans-esterification of vegetable oils, animal fats, and recycled greases. In this experiment, students prepared biodiesel through the base-catalyzed trans-esterification of several vegetable oils, which were subsequently analyzed in comparison with conventional petroleum-based fuels to assess their physical properties and to obtain a thermochemical profile. The experiment as described here could be employed by university faculty as a project in a major’s level laboratory course, but we envision the ideal fit to be a module within an advanced or integrated laboratory course. Students completing the project gain valuable experience in chemical synthesis and in extensive product characterization and analysis. This project reinforces critical skills in isolation of pure products from complex mixtures and in the careful preparation of samples for chemical analysis. Finally, students are afforded the opportunity to compare theoretical predictions from chemical modeling in combination with GC−MS analysis with the practical results gained by performing bomb calorimetry. KEYWORDS: Upper-Division Undergraduate, Interdisciplinary/Multidisciplinary, Laboratory Instruction, Consumer Chemistry, Physical Properties, Calorimetry/Thermochemistry

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INTRODUCTION The procurement of alternative fuel sources is an area of growing concern due to the rising energy demands of a growing population.1 One of the possible solutions to this problem is the use of biodiesel as an alternative to the petroleum-based diesel fuels currently in use today. A viable solution is especially important to the Department of Defense (DoD) due to the incredible annual fuel needs to power military vehicles and aircraft. The benefits of using biodiesel versus petroleum-based diesel are numerous, including reduced sulfur and carbon monoxide emissions, renewability, and better combustion. However, there are challenges that must be overcome concerning biodiesel: higher emissions of nitrogen oxides, higher production costs, and problematic cold-flow properties.2 Therefore, we have envisioned a project for upperlevel undergraduates wherein students use their synthetic skills to produce samples of biodiesel and then employ analytical and physical chemistry skills to analyze the synthetic biodiesel products in comparison with several conventional petroleumbased fuel sources. Indeed, several reports have appeared in this Journal emphasizing the synthesis and evaluation of biodiesel;3 however, the multidimensional analysis of the resulting biodiesel product, especially in comparison with conventional petroleum-derived fuels, has been limited.4 In this This article not subject to U.S. Copyright. Published XXXX by the American Chemical Society

study, we analyzed several different synthetic biodiesel (BD) fuels obtained through base-catalyzed trans-esterification. In addition, several conventional petroleum-based fuels were chosen for comparative analysis including no. 2 diesel, kerosene, and JP-8. A typical fuels profile was developed that is inclusive of the following characteristics: density, refractive index, viscosity, and cold-flow properties.2 This project also involved an emphasis on combustion properties and the effect of fatty-acid methyl ester (FAME) composition and structure on fuel potential. Students explore the chemical composition of the fuels through GC−MS analysis and use that information in conjunction with Molecular Orbital Package (MOPAC) molecular modeling to generate a thermochemical profile for each fuel.

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EXPERIMENT OVERVIEW The objective of this experiment is to prepare samples of BD and to conduct a comparative analysis of the biodiesel products with conventional fuel sources. The specific goals of the experiment include the following: (1) preparation of biodiesel Received: March 26, 2018 Revised: July 10, 2018

A

DOI: 10.1021/acs.jchemed.8b00216 J. Chem. Educ. XXXX, XXX, XXX−XXX

Journal of Chemical Education

Laboratory Experiment

Scheme 1. Trans-Esterification of Triglycerides To Produce FAMEs

most time-consuming. We would advise an additional period (1 × 1 h) for instructions on how to execute calculations using the provided bomb calorimetry data workup template (see Supporting Information). Following the laboratory work, students interpreted results by way of comparative analysis and then used that information to write a mock memorandum to Air Force leadership documenting their findings and proposing a recommendation for alternative fuel use. This exercise requires some out-of-class time to complete, but this is in line with the normal commitment for writing an undergraduate laboratory report. The modular nature of the experiment as described allows instructors to incorporate the work in its entirety or to adapt individual modules at their discretion. In addition, there are other experiments that instructors may adopt to augment the work described here. For example, instructors may want to determine the trace water content in the biodiesel samples, which is an important consideration for the practical use of biodiesel as a fuel source. Indeed, trace water can impact several aspects of the fuel including reduction of heat of combustion, fuel system corrosion, formation of ice crystals within the fuel itself, and harboring conditions for microbial growth within the fuel tank. As such, we believe a nice addition to the suite of experiments described here is the Karl Fischer titration, an effective technique for quantifying the amount of water in biodiesel.8

from several feedstocks using base-catalyzed trans-esterification chemistry; (2) determination of the physical properties of fuel samples by collecting refractive index, density, viscometry, and cloud point data; and (3) evaluation of the theoretical and empirical heats of combustion (energetics) of the fuels by MOPAC modeling and bomb calorimetry. Detailed procedures for the synthesis of biodiesel and for the various analytical methods can be found in the Supporting Information. Instructors can obtain MOPAC 2016 molecular modeling freeware via the Internet.5 In order to use MOPAC, instructors also need to obtain ChemSketch freeware to draw structures and create input z-matrix files.6 This project has been used in an upper-division integrated chemistry laboratory course at US Air Force Academy over the past 6 semesters with 52 cadets with good reproducibility. This experiment is amenable to sections of 10−12 students either as individual experiments or by work in pairs, but sections larger than that may not be ideally suited to level engagement needed between instructor and student. It is recommended that students work in pairs to facilitate the breadth of data collection and management that is needed in the project. All laboratory manipulations, consumables, equipment, and glassware are typical of a standard undergraduate laboratory. Required equipment and instrumentation includes bomb calorimeter, falling ball viscometer, refractometer, GC−MS, and DSC. Other methods can be substituted for DSC to afford the cloud point determination.3b,7 The project as described herein occurs over five 2 h lessons (10 total lab hours). In a more traditional setting, the entire project could be accomplished within a 3 × 3 h period. The first lesson is dedicated to the isolation of sunflower oil from 20 g of sunflower seeds by first grinding to a fine powder using a conventional coffee grinder, followed by Soxhlet extraction. The extraction in hexanes nominally requires 1 h to obtain an acceptable amount of sunflower oil. If time permits, the Soxhlet extraction can be left for an extended period of time (perhaps until the end of the day) and then stopped. This option would require the student to return to the lab outside of normal contact time to attend to the extraction. However, this is the only process that would engage students outside of the normal laboratory hours. The extraction period affords time for the instructor to demonstrate the MOPAC modeling of fuel components or the use/calibration of the bomb calorimeter. During the second lesson, the remainder of the BD samples is prepared by base-catalyzed trans-esterification. The synthesis and isolation of biodiesel requires an additional 1.5−2 h of clock time, but can be reasonably accomplished during the second lesson. The next several lessons are devoted to the analysis of the fuels. With an extended laboratory time, we would expect the complete analysis could be accomplished easily within 2 × 3 h periods with bomb calorimetry being the

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HAZARDS All organic solvents in this experiment include flammable liquids that are toxic by inhalation. Prudent use of personal protective equipment is recommended, and all manipulations described here were carried out in a standard operating fume hood. Always consult the materials safety data sheet (MSDS) for chemicals before executing this laboratory with referenced CAS numbers. Students should avoid chemical contact by wearing gloves and working in an adequate fume hood environment especially as it pertains to the following chemicals: chloroform/dichloromethane (suspected carcinogen and reproductive system effects), methanol (skin irritant, sensitizer, mutagen), hexanes (peripheral neurotoxic effects; flammable), and sodium hydroxide (caustic). Particular attention should be paid to executing the bomb calorimeter, and it is very important to never overload the decomposition vessel with too much sample! See the notes for instructors (Supporting Information) for detailed directions. ALWAYS depressurize the combustion vessel prior to opening the vessel.

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RESULTS AND DISCUSSION The experiment begins with the isolation of sunflower oil from sunflower seeds. A brief prelab lecture covers the details of this B




Table 1. Comparison of Physical Propertiesa of Various Fuel Samples

extraction emphasizing the aliphatic nature of the extract and the fact that its structure affords a facile isolation of the oil using a simple hydrocarbon solvent (hexanes) by way of Soxhlet extraction. The Soxhlet methodology here is attractive as it richly demonstrates the concept of continual extraction reinforcing the partitioning equilibrium concept first encountered in the organic chemistry laboratory course. It is worth noting here that the yield of actual sunflower oil from the seeds is sparse (2−4 mL). As such, it is important that the instructor augment with off-the-shelf sunflower oil. Initially, we thought the augmentation was not desirable, but soon realized the value of students directly observing the low yield of triglyceride which clearly illustrates the concentration challenges associated with exploiting natural products as feedstocks in biofuel production. Once isolated, the oil can be used for the subsequent transesterification reaction (Scheme 1). The reaction is straightforward allowing for quick conversion to the corresponding fattyacid methyl esters (FAMEs) providing an excellent practical example of the nucleophilic acyl substitution reaction. In order to provide a broad spectrum of examples, several other vegetable oil sources are employed, including cooking oils from the local supermarket and used oils from the campus dining hall. Following a brief workup, the resulting biodiesel is separated from glycerol yielding an ample quantity (15−18 mL) for the subsequent series of analyses. The reproducibility success rate for production of biodiesel via the method described in the Supporting Information is excellent with an extremely small number of students ever needing to repeat the strategy. In addition to BD, the instructor acquires several different conventional fuel sources as they provide an excellent basis of comparison both in terms of the measured physical characteristics that are obtained, but also for thermochemical considerations. Our department has access to jet fuel by way of the Air Force Research Laboratories, but conventional fuels such as no. 2 diesel are simply acquired at the local gas station. A battery of tests is performed on each of the fuel samples. The normal routine employed in our laboratory is to have each student complete the library of analyses on one biodiesel sample and one conventional fuel. The samples are initially analyzed via density, refractive index, viscosity, and cloud point; a summary of typical student data can be found in Table 1. Density was determined simply by transfer of a 100 μL aliquot via volumetric pipet to a tared test tube on the analytical balance (0.0001 g); viscometry was determined by employing a Gilmont falling ball viscometer and refractive index by use of an Edmund Optics standard Abbe refractometer. Like the other analyses performed, greater precision was achieved by acquisitions in triplicate with averaging of the series of runs. Following a brief demonstration by the instructor, viscometry and refractometry can be readily done independently by the students. The refractive index and density provide the starting point in the analysis of fuel quality. Refractive index may be used to ascertain the efficiency of trans-esterification and, furthermore, to verify purity.9 A pure biodiesel is desired to produce reliable heats of combustion measurements later in the experiment. All of the BD samples should have similar refractive indices due to their analogous chemical makeup, with the exception of FAMEs produced from palm oil, which has a divergent fattyacid source profile (Table 1 and Table S1). The literature values for biodiesel and No. 2 diesel are estimated to be 1.4548

Fuel Source Palm oil FAME Soybean oil FAME Rapeseed oil FAME Sunflower oil FAME Used vegetable oil FAME No. 2 diesel Kerosene JP-8

Density,b kg/m3

Refractive Index

Viscosity, mm2/s

Cloud Point, °C

843.0 873.0 821.0 814.0

1.4462 1.4551 1.4564 1.4628

6.242 4.955 6.311 6.504

10.41 −3.15 −8.12 −3.86

892.0

1.4563

6.298

−2.16

832.0 801.0 804.0

1.4582 1.4320 1.4470

2.919 2.327 2.257

−18.83 NAc NAd

a

Actual student data from runs conducted by 52 students. bDensity was determined at 25 °C. cFreezing event observed at onset temperature of −52.59 °C. dFreezing event observed at onset temperature of −50.12 °C.

and 1.4650, respectively.10 The results (Table 1) showed good agreement between student values and literature values, and confirm that the transformation was acceptable suggesting biodiesel samples are reasonably pure in content. The remaining refractive indices for conventional fuels were reported for comparative purposes only with the density being used to confirm product purity. The densities of BD samples reasonably vary as a function of composition, but the acceptable range is 866−878 kg/m3 (Table 2).11 As shown in Table 1, the densities for the BD Table 2. Standards of Density and Viscosity for Biodiesel and Select Petroleum-Derived Fuelsa

a

Fuel

Density at 15 °C, kg/m3

Viscosity at 40 °C, mm2/s

Biodiesel No. 2 diesel Kerosene JP-8

866−878 823 780−810 775−840

3.50−5.00 2.00−4.50 1.25−1.50 1.50

See refs 8 and 9.

samples tested tend to be beyond this target with values ranging from 821 to 892 kg/m3. These results bring into question the relative purity of the products isolated following trans-esterification and contrast the findings from refractive index. Pedagogically, this is an acceptable scenario as it provides the students with the opportunity to make a critical determination relative to the validity of the two methods and to rationalize the observed outcomes. Indeed, the samples may be contaminated with reaction byproducts such as residual glycerol or soaps, which could impact the density values obtained. On the basis of combined results from refractive index and density determinations, it appears that soybean oil derived FAMEs and used vegetable oil derived FAMEs provide the optimal samples for further analysis with reported RIs of 1.4451 and 1.4563 and densities of 873 and 892 kg/m3, respectively.11,12 Regarding conventional fuels, diesel fuel is reported to have a density of 823 kg/m3, while kerosene and JP-8 have densities of around 800 kg/m3 (Table 2).13 Given the results presented in Table 1, it appears that the conventional fuels are of excellent quality with values comparable to the literature precedence. At this point, the extended key pedagogical goal is for students to understand the relationship among density, C




Figure 1. Structures of major isomers present in palm oil and rapeseed oil biodiesel.

viscosity, and cloud point. Viscosity values (Table 1) are in line with expected values and show good reproducibility.11 In addition to viscosity, cloud point also plays a critical role in determining practical fuel usage. The cloud point of a substance represents the temperature at which the substance begins to form small solid crystals, which may clog engine filters leading to severe issues in performance. The cloud point values obtained by DSC are summarized in Table 1. If the institution does not have access to DSC, there are alternative options that could be employed to obtain cloud point data.3b,14 By DSC analysis, it should be noted that kerosene or JP-8 failed to show the expected temperature inflection, and an actual freezing event was observed at temperatures lower than −50 °C. Regardless, the resulting cloud point data clearly represent the challenges for broad implementation of alternative fuels across the climate spectrum of the US and provide an excellent discussion theme for students. For example, students may consider the blending of biodiesel with petroleum-based diesel to produce a fuel source that is amenable to use in harsher climates. Furthermore, the results provide an ideal opportunity for students to correlate the observed cloud point data with chemical structure and with the earlier determined viscosity values. Because cloud point, in effect, represents the freezing point of the sample, intermolecular forces affect the temperature at which this phase change occurs. Students are therefore prompted to consider how IM forces such as van der Waals forces, degrees of unsaturation in the extended hydrocarbon chain, and the presence of isomers may impact the observed properties. In light of the cloud point results, a semiquantitative GC− MS analysis was conducted to study molecular structure effects of cloud point and to set the stage for evaluating the thermochemical phenomena associated with combusting the fuel. The common FAME standards were independently acquired using the same GC−MS conditions and saved for the students as references. The FAME composition of each biodiesel was then determined through a comparative analysis between the reference standards and the synthesized biodiesel samples. The relative proportion of each ester in the biodiesel sample was found via integration of individual peak regions arising in the GC (see Table S1 in Supporting Information). Table S1 shows that palm oil FAME was composed of primarily methyl palmitate and methyl oleate. Rapeseed oil, on the other hand, is composed almost entirely of methyl linoleate and methyl oleate. This striking dissimilarity in FAME distribution perhaps contributes to the observed differences in physical properties. Students recall that rapeseed oil FAME and palm oil FAME exhibited the lowest and highest cloud points (Table 1), respectively. Moreover, it is interesting to

note that methyl linoleate and methyl oleate both have units of unsaturation while methyl palmitate is completely saturated in the carbon chain (Figure 1). These structural attributes provide a key talking point for students in their assessment of the observed physical behavior (i.e., cloud point) of the various fuels. With acceptable GC−MS data in hand, a thermochemical evaluation profile of the various fuels was developed. Instead of acquiring empirical thermochemical energy values for each fuel, quantum mechanical estimates were collected through the use of MOPAC molecular modeling software and were used to calculate theoretical energy values. Table S2 (Supporting Information) shows the primary compositional profile for each of the conventional fuels. It is important to note that, in the actual gas chromatogram (see Figures S1−S3 in the Supporting Information), students observed a plethora of peaks and students are pointed to the fact that these fuel samples are considerably more complex in composition relative to the biodiesel samples. Particular attention is drawn to the presence of isomers in the mixture. As a result, we opt to deconvolute the results by focusing solely on the major straight-chain isomers present in the mixture. It is vital to point out to students that any predictions made from this point forward are compromised by the deconvolution estimation of the fuel composition. However, the estimation affords an easier way forward for students to conduct analyses without adversely affecting the major experimental conclusions. More importantly, the generalized profiles shown in Tables S2 and S3 (Supporting Information) clearly illustrate the key compositional differences among the conventional fuels and allow easy comparison with the biodiesel samples. The stoichiometric values of this reaction are given in the equation below, which can be employed to estimate heat of combustion, where α is the coefficient of the ester/hydrocarbon, β is the coefficient of oxygen, γ is the coefficient of carbon dioxide, and δ is the coefficient of water. MOPAC affords determination of the ΔHf for each component (ester or HC) in the fuel sample. Using the balanced chemical equation, the calculated heats of combustion for each FAME and conventional fuel can be determined as the summation of the individual contributions for each component in the mixture (Tables S1 and S2). The values are reported in kJ/mol and kcal/mol allowing easy comparison with literature values of which there is good agreement.10 α[ester/HC] + β[O2 ] → γ[CO2 ] + δ[H 2O]

(1)

From here, the contribution of each component to overall heat of combustion was calculated as shown in Figure 3 of the Student Handout (Supporting Information, p S11). In D




addition, the values were then converted to kJ/g to allow students to make a direct comparison of the calculated heats of combustion with the experimentally derived values from bomb calorimetry (Table 3). Table 3. Comparison of Calculated and Experimentally Determined Heats of Combustion for Various Fuels Fuel Source

Calculateda ΔHc, kJ/g

Experimentalb ΔHc, kJ/g

Palm oil FAME Soybean oil FAME Rapeseed oil FAME Sunflower oil FAME Used vegetable oil FAME No. 2 diesel Kerosene JP-8

−44.91 −44.87 −44.97 −44.94 −44.93 −53.23 −53.51 −53.47

−38.48 −38.45 −43.07 −42.89 −40.41 −47.21 −46.02 −46.65

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AUTHOR INFORMATION

Corresponding Author

*E-mail: [email protected]. ORCID

Timm A. Knoerzer: 0000-0002-4764-3025 Gary J. Balaich: 0000-0003-3722-3112 Notes

The authors declare no competing financial interest.

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a

Data calculated using the templates provided in Supporting Information. bResults from runs conducted by 52 students.

ACKNOWLEDGMENTS We would like to thank the undergraduates from the integrated laboratory course for judiciously conducting these experiments.

Empirical heats of combustion were measured by bomb calorimetry and the algorithm is presented in Figure 2 of the Student Handout (editable spreadsheet available in Supporting Information). Several corrections are included in the spreadsheet to provide precise calculations of the experimental ΔHc. The results showed good internal consistency, but were approximately 8−10% lower than the calculated values for the biodiesel samples and 18−20% lower for the conventional fuels (Table 3) ascribed to purity of sample for biodiesel and deconvolution assumptions in the case of the conventional petroleum-based fuels. Regardless, viable results were generated in either case clearly showing the heat of combustion output differences between biodiesel and conventional fuels.

REFERENCES

(1) Nocera, D. G. On the Future of Global Energy. Daedalus 2006, 135 (4), 112−115. (2) (a) Geacai, S.; Nita, I.; Iulian, O.; Geacai, E. Refractive Indices For Biodiesel Mixtures. U.P.B. Sci. Bull., Series B 2012, 74 (4), 149− 160. (b) Boehman, A. L.; Morris, D.; Szybist, J.; Esen, E. The Impact of the Bulk Modulus of Diesel Fuels on Fuel Injection Timing. Energy Fuels 2004, 18, 1877−1882. (3) (a) Clarke, N. R.; Casey, J. P.; Brown, E. D.; Oneyma, E.; Donaghy, K. J. Preparation and Viscosity of Biodiesel from New and Used Vegetable Oil. J. Chem. Educ. 2006, 83, 257−259. (b) Akers, S. M.; Conkle, J. L.; Thomas, S. N.; Rider, K. B. Determination of the Heat of Combustion of Biodiesel Using Bomb Calorimetry. J. Chem. Educ. 2006, 83, 260−262. (c) Bucholtz, E. C. Biodiesel Synthesis and Evaluation: An Organic Chemistry Experiment. J. Chem. Educ. 2007, 84, 296−298. (d) Behnia, M. S.; Emerson, D. W.; Steinberg, S. M.; Alwis, R. M.; Dueñas, J. A.; Serafino, J. O. A simple, Safe Method for the Preparation of Biodiesel. J. Chem. Educ. 2011, 88, 1290−1292. (e) De La Rosa, P.; Azurin, K. P.; Page, M. F. Z. Soybean Oil: Powering a High School Investigation of Biodiesel. J. Chem. Educ. 2014, 91, 1689−1692. (f) Daconta, L. V.; Minger, T.; Nedelkova, V.; Zikopoulos, J. N. Organic Chemistry and the Native Plants of the Sonoran Desert: Conversion of Jojoba Oil to Biodiesel. J. Chem. Educ. 2015, 92, 1741−1744. (g) Goldstein, S. W. Biodiesel from Seeds: An Experiment for Organic Chemistry. J. Chem. Educ. 2014, 91, 1693− 1696. (h) Bladt, D.; Murray, S.; Gitch, B.; Trout, H.; Liberko, C. Acid-Catalyzed Preparation of Biodiesel from Waste Vegetable Oil: An Experiment for the Undergraduate Organic Chemistry Laboratory. J. Chem. Educ. 2011, 88, 201−203. (i) Gross, E. M.; Williams, S. H.; Williams, E.; Dobberpuhl, D. A.; Fujita, J. Synthesis and Characterization of Biodiesel from Used Cooking Oil: A Problem-Based Green Chemistry Laboratory Experiment. In Green Chemistry Experiments in Undergraduate Laboratories; Fahey, J. T., Maelia, L. E., Eds.; ACS Symposium Series 1233; American Chemical Society: Washington, DC, 2016; pp 71−92. (4) Pierce, K. M.; Schale, S. P.; Le, T. M.; Larson, J. C. An Advanced Analytical Chemistry Experiment Using Gas Chromatography-Mass Spectrometry, MATLAB, and Chemometrics to Predict Biodiesel Percent Composition. J. Chem. Educ. 2011, 88, 806−810. (b) Ault, A. P.; Pomeroy, R. Quantitative Investigations of Biodiesel Fuel Using Infrared Spectroscopy: An Instrumental Analysis Experiment for Undergraduate Chemistry Students. J. Chem. Educ. 2012, 89, 243− 247. (c) Feng, Z. V.; Buchman, J. T. Instrumental Analysis of Biodiesel Content in Commercial Diesel Blends: An Experiment for

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CONCLUSION The protocol for a project-based preparation and analysis of biodiesel in comparison with a series of conventional fuel sources has been described. The project involves a multifaceted, comparative analysis of various fuel samples that provides broad exposure to key laboratory techniques for undergraduates while providing enrichment of critical chemical concepts. The breadth of this project allows students to evaluate the limitations of methodologies, but also to ascertain the physical properties that lead to the optimization of the critical characteristics that may be of interest to the development of a viable alternative fuel. Topics for discussion included mechanistic organic chemistry, intermolecular forces, thermochemistry, chromatography, spectroscopic interpretation, or molecular modeling. Students complete the exercise by using the collected results to preliminarily identify a suggested alternative fuel source and to communicate the findings via a memorandum to Air Force leadership and by compiling results in the form of a comprehensive Supporting Information document.

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Excel template for bomb calibration calculations (XLSX) Excel template for bomb calorimetry calculations fuel samples (XLSX) Excel template for MOPAC heat of combustion calculations (XLSX) Fuels report example rubric (XLSX)

ASSOCIATED CONTENT

S Supporting Information *

The Supporting Information is available on the ACS Publications website at DOI: 10.1021/acs.jchemed.8b00216. Instructions for students, notes for instructor, and example student work (PDF, DOCX) E




Undergraduate Analytical Chemistry. J. Chem. Educ. 2012, 89, 1561− 1565. (5) http://openmopac.net/ (accessed July 2018). (6) http://www.acdlabs.com/resources/freeware/chemsketch/ (accessed July 2018). (7) Akhil, A. G.; Mohammed, A.K.P.K.; Akhilesh, S.; Muhammad, A. C. A.; Khan, S.; Kanna, R. Determination of Cloud and Pour Point of Various Petroleum Products. Int. Ref. J. Eng. Sci. 2017, 6 (9), 1−4. (8) (a) MacLeod, S. K. Moisture Determination Using Karl Fischer Titrations. Anal. Chem. 1991, 63 (10), 557A−566A. (b) Cedergren, A. Determination of Kinetics of the Karl Fischer Reaction Based on Coulometry and True Potentiometry. Anal. Chem. 1996, 68 (5), 784−791. (9) Nita, I.; Geacai, S.; Iulian, O. Measurements and Correlations of Physico-chemical Properties to Composition of Pseudo-binary Mixtures with Biodiesel. Renewable Energy 2011, 36 (12), 3417−3423. (10) Nita, I.; Geacai, S.; Neagu, A.; Geacai, E. Estimation of the Refractive Index of Diesel Fuel and Biodiesel Blends. Analele Universitatii ″Ovidius″ Constanta - Seria Chimie. 2013, 24 (1), 24−26. (11) (a) Esteban, B.; Riba, J.-R.; Baquero, G.; Rius, A.; Puig, R. Temperature Dependence of Density and Viscosity of Vegetable Oils. Biomass Bioenergy 2012, 42, 164−171. (b) Moradi, G. R.; Karami, B.; Mohadesi, M. Densities and Kinematic Viscosities in Biodiesel-Diesel Blends at Various Temperatures. J. Chem. Eng. Data 2013, 58 (1), 99−105. (c) Collins, C. Implementing Phytoremediation of Petroleum Hydrocarbons. Methods in Biotechnology 2007, 23, 99−108. (12) Xie, W.; Li, H. Hydroxyl Content and Refractive Index Determinations on Transesterified Soybean Oil. J. Am. Oil Chem. Soc. 2006, 83 (10), 869−872. (13) Yarranton, H. W.; Okafor, J. C.; Ortiz, D. P.; van den Berg, F. G. A. Density and Refractive Index of Petroleum, Cuts, and Mixtures. Energy Fuels 2015, 29, 5723−5736. (14) Chiu, C.-W.; Schumacher, L. G.; Suppes, G. J. Impact of Cold Flow Improvers on Soybean Biodiesel Blend. Biomass Bioenergy 2004, 27 (5), 485−491.

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Comparative Analysis of Fuel Composition and Physical Properties of

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