Implementation of Ultrasonic Microbubbles Method in Biodiesel Trans-esterification Process of a Vegetables Oil ResidueAgung Cahyono, Hakim Al Kausar, Dwi Wulandari, Bambang Susilo, Dimas Firmanda Al RizaDepartement of Agricultural of Engineering, Faculty of Agricultural Technology, University of Brawijaya Jl. Veteran Malang 65145

Corresponding author : 115100213111008@email.ub.ac.idAbstract. Biodiesel is one of choices of renewable energy that can be made by using vegetable or animal oils. In this study a residue of frying vegetable oil is used as the main ingredient. In a conventional batch trans-esterification process a mechanical stirrer is commonly used and it takes a considerable amount of time between 30 minutes to 2 hours for the reaction to be completed. The biodiesel conversion yield by conventional process is approximately 96%. Trans-esterification reaction kinetics must be considered to obtain an efficient process and better yield. The use of ultrasonic with horn type transducer (Braun Sonic 2000) in the process of trans-esterification reaction showed higher specific energy and can reduce specific energy in biodiesel processing than a conventional method and also shorten the processing time. The experiments were performed using a catalyst (KOH) and methanol with a molar ratio of (1:6) with a volume of 125 mL and carried out with process time between 3-25 minutes. The results show the highest biodiesel yield is 100% with process time of 3 minutes. Other measured parameters met the biodiesel standard with a great Flash Point of 107oC, density of 0.871 gram/mL, 9381.221 calorific value (calories/gram), the viscosity of 6 cP, and the processing time of 7 minutes obtained biodiesel conversion yield of 98.4% at 108oC Flash Point, Density 0.871 gram/mL, 9329.890 calorific value (calories/gram), and the viscosity of 6 cP.Keywords: biodiesel, trans-esterification, ultrasonic, used cooking oilINDONESIAN SCHOLARS JOURNAL Paper Number (Will be replaced with volume and paper number if the manuscript is accepted)

IntroductionNumerous attempts have been done to decrease the use of fossil fuels which its supply will be estimated run out in the next 25 years. These attempts should be done considering the gas emissions of this fuel such as CO2, PbO, CO, SO2, carbon and hydrocarbon which pollute the environment. Biodiesel is one of the alternative fuel for the transportations in which its produce less emissions (CO, HC, particle and dust) environmentally friendly and recyclable [1]. The serious increasing price of petroleum and the environmental effect has become the background for searching some alternative diesel fuels from renewable resources called biodiesel [2,3]. Biodiesel is a renewable alternative fuel produced through trans-esterification or esterification of fatty acids from plant oils [4].The use of Biodiesel which is mostly made from vegetable or animal oils is commonly contrasted to the foodstuffs. Cooking oil is leftover oil that is able to be utilized as the inexpensive and sustainable biodiesel materials. The aim of using this oil is utilizing waste and decreasing the carcinogenic impact leading to cancer. The cooking oil consumption with deep frying in Indonesia reaches 182 thousand ton along with the assumption that the half of this oil is wasted. Considering these data, it is assumed that the wasted oil reaches 91 thousand ton. Hence, the use of these materials must bring the higher economic value than the other biodiesel materials [5]. Oil-made Biodiesel production generally uses the mechanic stirrer. It has so many drawbacks such as: consume a large number of energy, numerous catalyst, lack of yield and time-consuming process. Therefore, it necessarily needs the effective method to solve these problems which is horn-jolted ultrasonic cavitation method. This method is used for it has several advantages such as: less time-consuming process, 99.99% productivity, small energy input, less number of catalyst and maximum generated product [6].Important RequirementsMaterialsThe used materials in this study consist of wasted cooking oil, KOH (base catalyst), methanol ( 90% degree) while the used aids consist of Braun Sonic 2000, measure glass (1000 ml, 500 ml, 200 ml), thermometer, centrifuge, Hot Plate/ Stirrer HP220, Timer, loaded (Volume 1000 ml, 1500 ml), Oscilloscope.MethodsThe applied method in this study is random design along with the analysis of time reaction of trans-esterification by head-jolted ultrasonic wave (Braun Sonic 2000) toward final biodiesel product after the trans-esterification process. The samples used in this study are 12 samples and the ultrasonic frequency used is stable on the Braun Sonic 2000 which is on the high frequency (29.53 kHz).Experimental DesignThe purpose of testing it is time to get the range of steady process of trans-esterification based on feculence glycerol formed. A mixture of oil and methoxide with a volume of 125 ml processed by ultrasonic waves horns a trill. The ratio of the molar oil and methanol made 1:6. The catalyst used is a concentration of 10 gram KOH per liter of the oil (equivalent 0.216 mole KOH/liters oil) continued with the use of a catalyst 1% or 0.9 grams. After the process of trans-esterification lasting the next process neutralized with H2SO4 and centrifugation in 5000 rpm for 3 minutes to see the volume of feculence glycerol. Calculation of Specific EnergyCalculation of specific energy obtained based on calculations energy obtained based on data specifications of instrument that stated in instrument Braun Sonic 2000. Immensity energy needs specific in processing palm oil biodiesel be obtained from equation 1. (1)

Percentage of the GlycerolPercentage of the glycerol obtained by volume glycerol acquired divided by volume material. Immensity percentage of volume glycerol obtained from equation 2.(2)

Results And Discussion1. The Effect of Time Process to the Value of Methyl Ester Cinematic ViscosityThe data of viscosity testimony in this study are the testimony result by using S-flow 3000v automatic viscosity system. This aid uses the set of mm2/s or known as centipoise (cP). The results of this test can be seen through the Figure 1.

Fig 1. The cinematic viscosity correlation graphic toward time

Figure 1 shows that the large of cinematic vescosity toward needed time of the transesterification process is not linier. It tends to up and down especially at the particular reaction time such as 9 minutes, 11 minutes, 13 minutes and 15 minutes. While the transesterification reaction over 15 minutes shows the stable increasing cinematic viscosity which is approximately on the 7 mm2/s. generally, it can be recognized that the longer time of trans-esterification process results the higher value of biodiesel viscosity toward these following times: 9,13,17,19,21,23 and 25 minutes in which these times are out of the Indonesian viscosity standard. It also happens in the research Fatmawati et al [7] that the large influence of cinematic viscosity toward the duration of trans-esterification reaction in creating biodiesel tends to increase due to the active of carbon bound resulting the decrease of biodiesel temperature. It also influences the fuel pump function. Consequently, it can be said that the cinematic viscosity value of biodiesel which is related to the SNI is less than 6 mm2/s, which is under reaction of 3, 5, 7, and 11 minutes.2. The Effect of Time Process to the Methyl Ester YieldThe higher value of the yield means the more growing number of the biodiesel percentage produced during the ongoing trans-esterification process. The yield value can be measured by dividing the final oils weight by the former oil weight and then times by 100%. Therefore, the yield is commonly expressed in the form of percentage (%) and the maximum yield of biodiesel is 100%. The yield of this study can be seen through the Table 1.Table 1. Biodiesel yield in the difference time variationsTime (minutes)Yield (%)

3100

594,4

798,4

996,8

1196,8

1395,2

1596

1795,2

1995,2

2198,4

2392

2595,2

According to the Table 1, it can be seen that the biggest yield is gained in the 3 minutes trans-esterification reaction with 100% of yield value. It shows that 100% of the materials can be converted into biodiesel. The trans-esterification biodiesel during 3 minutes can produce 125 ml biodiesel by using the former 125 ml cooking oil. While the smallest yield value is gained on the 23 minutes trans-esterification process which is 92%. The holistic biodiesel yield percentage tends to be unstable. However, the decrease tendency of biodiesel yield in this study is mostly caused by the decrease of methanol by result of increasing temperature of the ultrasonic radiation. This also happens in the research Zuliana et al [8] stating that methyl ester yield tends to decrease due to the trans-esterification reaction which is categorized as the reversible reaction. Therefore, the increasing time of trans-esterification reaction may cause the reverse reaction as well as the ethanol evaporation due to the increasing temperature. It eventually results the decreasing value of biodiesel yield.3. The Effect of Time Process to the Flash Point of Methyl Ester The result of flash point of methyl ester (biodiesel) can be seen through the Figure 2.

Flash Point (oC)

Time (minutes)

Fig 2. Flash point of methyl ester toward the trans-esterification timeTest result in figure 2 shows that the flash point of produced methyl ester mostly meets SNI 04-7182-2006 in which the minimum value of flash point for the biodiesel is 100oC. The lowest flash points gained in the low frequency treatment with 23 minutes of trans-esterification process which is 44 C. While for the highest bur point is 114 C in 15 minutes trans-esterification treatment. According Setiawati et al [9] the flash point primarily links to the safety during the saving and handling process, in which the flash point shows the ability whether or not it can be burned and evaporated (volatility). Thereby, flash point value of biodiesel which is produced above 100oC has been feasible to be used.4. Time Influence of Trans-esterification Toward the Heat Value of Methyl EsterHeat value shows the bigger energy amount which is freed by the fuel through the perfect combusting reaction per set of mass or fuel volume. From the biodiesel manufacture through the use of this cooking oil, it is gained the heat value of biodiesel as seen in the Figure 3.

Heat Value (cal/gram)

Fig 3. Heat value of methyl ester toward the trans-esterification process

Time (minutes)

According to the Figure 3 it can be seen that the highest heat value is gained in 19 minutes of trans-esterification reaction with the heat value is over 10,000 cal/gram and the lowest heat value is gained in 9 minutes which is 8.000 cal/gram. According to SNI the heat value of biodiesel should be more than 27.65 Btu/lb. The inconstant increase of heat value shows that the time does not significantly influences toward the degree of heat value of produced biodiesel. The insignificance of this matter also happens in the research conducted by Fatmawati et al [7] which states that the heat value of biodiesel tends to be stable.5. Time Influence of Trans-esterification Toward the Methyl Ester Density ValueThe density or substance mass in biodiesel has the significant role toward its cinematic viscosity since this density value is directly proportional to its cinematic viscosity value. In biodiesel, the density value shows the number of pollutant substances, such as soap and glycerol as the result of soaping reaction, unconverted fat which later becomes ester, water, wasted hydroxide sodium, or even unreacted waste methanol [9]. The result of methyl ester density toward the time influence can be seen through Figure 4.Time (minutes)Density (gram/ml)

Fig 4. Density value of methyl ester toward the trans-esterification processFigure 4 shows that the density value of methyl ester produced form the trans-esterification reaction toward the cooking oil mostly in the number of 0.869-0.872 gr/ml. These numbers holistically meets the criteria of biodiesel based on SNI which is 0.85-0.9 gr/ml. The highest value of methyl ester density is during 9, 11, 13, 15, 17, 21 and 23 minutes of trans-esterification process which is 0.872 g/ml while for the lowest value is in 25 minutes of trans-esterification process which is 0.870 gr/ml. based on the picture 4, it can be seen that the value of methyl ester density tends to be unstable which is marked by up and down the density value in each reaction time. This result goes in a line with the research conducted by Arfika et al [10] in which the methyl ester density value is significantly increased but then fall back as the increase of the trans-esterification time in the process of biodiesel manufacture.6. Energy CalculationOn the research of Sholikah et al [11] specific energy needs, biodiesel processing at optimal conditions with ultrasonic wave of 576 kJ/liters. According to Susilo [12]; using mechanical energy specific stirring to the specifications that engine as follows: Heater 1kwatt, the process of 30 minutes, TG conversion to E: 96%, and the Capacity 1,5 liters of every process. The energy needs of each liter of biodiesel, Trans-esterification products:

It shows that the use of ultrasonic wave trans-esterification need to the process of energy specific stirrer lower than the use of mechanical.ConclusionReference used cooking oil can be used as a potential materials for biodiesel manufacture. The process of making biodiesel from wasted cooking oil may use method which applies the horn-jolted ultrasonic as trans-esterification with 1% of KOH catalyst and 90% methanol concentration. Based on the results of this study, it was found that biodiesel has complied with SNI 04-7182-2006 in which the best results are in the trans-esterification reaction for 3 minutes which resulted in 100% yield, 6 cP of cinematic viscosity, 0.871 g/ml od density, 107oC of flash point and 99831.211 cal/g of the heat value at a frequency of 29.53 kHz ultrasonic waves.AcknowledgementWe gratefully to Dr. Ir. Bambang Susilo, M.Sc.Agr and Dimas Firmanda Al Riza, ST, M.Sc., as the supervisor who has helped us in the preparation of the experiment, in the form of guidance, discussion, referrals, and prayer. And also acknowledge to all those who have helped both moral support and prayers which the writer cannot mention here. This paper will be more complete with head vice and constructive criticism to improve the preparation of subsequent papers. Finally, the author hopes that the preparation of this paper can be useful.REFERENCES[1] Hanif. 2009. Analisis Sifat Fisik dan Kimia Biodiesel Dari Minyak Jelantah Sebagai Bahan Bakar Alternatif Motor Diesel. Jurnal Teknik Mesin Vol. 6 No.2. Jurusan Teknik Mesin Fakultas Teknik. Padang : Politeknik Negeri Padang [2] Ganapathy T, Murugesan K, Gakkhar RP. Performance optimization of Jatropha biodiesel engine model using Taguchi approach. Appl Energy2009;86:247686.[3] Tiwari AK, Kumar A, Raheman H. Biodiesel production from jatropha oil (Jatrophacurcas) with high free fatty acids: an optimized process. Biomass Bioenergy 2007;31:56975.[4] Susilo, Bambang. 2009. Model Kavitasi Irradiasi Gelombang Ultrasonik pada transesterifikasi minyak Tanaman Menjadi Biodiesel. Universitas Brawijaya. Malang[5] Ketaren S. 2008. Pengantar Teknologi Minyak dan Lemak Pangan. Jakarta : Penerbit Universitas Indonesia.[6] Supardan, D.M. 2O11. Penggunaan Ultrasonik untuk Transesterifikasi Minyak Goreng Bekas. Jurnal Rekayasa Kimia dan Lingkungan. vol.8. no.1. pp.11-16[7] Fatmawati, Dewi dan Putri Diliyan Shakti. 2013. Reaksi Metanolisis Limbah Minyak Ikan Menjadi Metil Ester Bahan Bakar Biodiesel Dengan Menggunakan Katalisis NaOH. Jurnal Teknologi Kimia dan Industri Vol.2 No.2 (68-75). Jurusan Teknik Kimia Fakultas Teknik. Semarang : Universitas Diponegoro[8] Zuliyana dan Maharani Nurul Hikmah. 2010. Pembuatan Metil Ester (Biodiesel) Dari Minyak Dedak dan Metanol Dengan Proses Esterifikasi dan Transesterifikasi. Jurusan Teknik Kimia Fakultas Teknik. Semarang : Universitas Diponegoro[9] Setiawati, Eva dan Fatmir Edwar. 2012. Teknologi Pengolahan Biodiesel Dari Minyak Goreng Bekas Dengan Teknik Mikrofiltrasi dan Transesterifikasi Sebagai Alternatif Bahan Bakar Mesin Diesel. Jurnal Riset Industri Vol.VI No.2 (117-127). Banjarbaru : Balai Riset dan Standardisasi Industri Banjarbaru[10] Arfika, Farid Widi, Lizda Johar Mawarani, Agung Budiono. 2013. Pengaruh Perendaman Ampas Tebu Sebagai Biomaterial Adsorbent Pada Proses Preatreatment Terhadap Karakteristik Biodiesel Minyak Jelantah. Jurnal Teknik POMITS Vol.1 No.1 (1-7). Jurusan Teknik Fisika Fakultas Teknik Industri. Surabaya : Institut Teknologi Sepuluh Nopember.[11] Sholikhah, Noor. 2010. Efek Penerapan Gelombang Ultrasonik Pada Proses Transesterifikasi Minyak Sawit ( Elaeis Guineensis ) Menjadi Biodiesel. Skripsi[12] Susilo, B. 2008. Model Kinetik Transesterifikasi Minyak Sawit Menjadi Biodiesel Dengan Gelombang Ultrasonik. Disertasi-UB. MalangChart10.8710.8710.8710.8720.8720.8720.8720.8720.8710.8720.8720.87

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