An Ultrasound Assisted Transesterification to Optimize Biodiesel Production from Rice Bran Oil

The ultrasound method is used to improve mass transfer between incompressible reactants which increases their chemical reaction and reduces reaction time as well as energy consumption. In this research, transesterification process variables of rice bran oil were optimized using response surface methodology (RSM). Three process parameters were investigated, namely methanol to oil molar ratio, catalyst concentration, and time. The optimum conditions of the transesterification process based on RSM were: (1) methanol to oil molar ratio: 1:6; (2) catalyst concentration: 0.5% wt.; and (3) time: 48 min, with methyl ester yield of 94.12 %. The optimum rice bran methyl ester yield predicted by RSM was validated by replicating three independent parameters with showed average rice bran methyl ester yield of 93.98%. The properties of the rice bran biodiesel properties were measured and the values met the requirements of the ASTM D6751 and EN 14214 standards.

Biodiesel; Response surface methodology; Rice bran; Ultrasound

Rapid depletion of fossil fuels coupled with increasing awareness of environmental issues, concerns over rising greenhouse gas emissions and escalating petroleum prices have prompted scientists and researchers to explore renewable and environmental friendly alternative energy sources (Salaheldeen et al., 2015; Said et al., 2018). Biodiesel is a type of renewable fuel, biodegradable, non-toxic and a potential alternative for fossil fuel (Tse et al., 2015; Leong, et., 2016). Rice (Oryza sativa Linn) bran is a thin layer between the rice and its husk which is removed to polish the rice. It consists of pericarp, tegmen (endosperm covering layer), aleurone and sub -aleurone. (Ju and Vali, 2005) and makes up 8% of the harvested rice. The oil content of rice bran is about 16-32% based on its weight (Anwar et al., 2005).  The oil composition of jatropha and rubber seed are higher accounting for 55% and 45% of their respective total weight (Ramadhas et al., 2005).

        Ultrasound is an energy that absorbs mass and heat transfer which is an alternative reaction system that can increase the synthesis of biodiesel process (Maghami et al., 2015). In recent years, researches have applied ultrasound probes, ultrasound baths or horns sonochemical reactors in biodiesel synthesis (Koutsouki et al., 2016). Compared with the conventional method, the ultrasound-assisted methods have the advantages of shorter reaction time, less catalyst time, higher methyl ester yields, and less energy in biodiesel production. (Prakash Maran and Priya, 2015). Response surface methodology (RSM) is an effective statistical technique used to establish the relationship between a set of experimental parameters and results. The RSM defines the effect of the independent variables, and also generates mathematical models. Therefore, many researchers have studied biodiesel production using RSM in order to produce high methyl ester and improve the quality of biodiesel (Dharma et al., 2016; Sebayang et al., 2017; Milano et al., 2018).

The present study is aimed at optimising the transesterification of rice bran oil using an ultrasound technique. The properties of the rice bran methyl ester were investigated using EN 14214 and ASTM D6751 standards. Results showed producing biodiesel using ultrasound can save cost, time and energy.

In this study, ultrasound-assisted biodiesel production from crude rice bran oil was evaluated through RSM modelling. The optimisation process was conducted based on three main parameters: methanol to oil ratio, reaction time and catalyse concentration. The optimal parameters are methanol to oil ratio 6:1, reaction time: 48 min and catalyst used: 0.51 wt.%. The methyl ester yield predicted under these process conditions is 94.12%. The limitation of this experiment was the capacity the equipment. Therefore, using a more powerful ultrasound can be explored in future studies to find out if that increases yields. Results showed the RSM model is reliable in predicting the values of dependent variables on the conversion of rice bran methyl ester using ultrasound.

    The authors express their gratitude to Direktorat Jenderal Penguatan Riset dan Pengembangan Kementerian Riset dan Teknologi, Badan Riset dan Inovasi Nasional Republik Indonesia (Grant No. 032/SP2H/LT/DRPM, No. 147/SP2H/LT/DRPM/2019) and Politeknik Negeri Medan, Medan, Indonesia. 

Anwar, F., Anwer, T., Mahmood, Z., 2005. Methodical Characterization of Rice (Oryza sativa) Bran Oil from Pakistan. Grasas Aceites, Volume 56, pp. 125­–134

Balat, M., Balat, H., 2008. A Critical Review of Bio-diesel  as a Vehicular Fuel. Energy Conversion and Management, Volume 49, pp. 2727–2741

Dharma, S., Masjuki, H.H., Ong, H.C., Sebayang, A.H., Silitonga, A.S., Kusumo, F., Mahlia, T.M.I., 2016. Optimization of Biodiesel Production Process for Mixed Jatropha Curcas–Ceiba Pentandra Biodiesel using Response Surface Methodology. Energy Conversion and Management, Volume 115, pp. 178–190

Dwivedi, G., Sharma, M.P., 2015. Application of Box–Behnken Design in Optimization of Biodiesel Yield from Pongamia Oil and its Stability Analysis. Fuel, Volume 145 , pp.256–262

Ejikeme, P., I. Anyaogu, C. Ejikeme, N. Nwafor, C. Egbuonu, K. Ukogu, and J. Ibemesi. 2010. Catalysis in biodiesel production by transesterification processes-An insight. Journal Chemical, Volume 7, pp.1120–1132

Ju, Y.-H., Vali, S.R., 2005. Rice Brand Oil as a Potential Resource for Biodiesel: A Review. Journal of Science and Industrial Research, Volume 64, pp. 866–882

Koutsouki, A.A., Tegou, E., Badeka, A., Kontakos, S., Pomonis, P.J., Kontominas, M.G., 2016. In Situ and Conventional Transesterification of Rapeseeds for Biodiesel Production: The Effect of Direct Sonication. Industrial Crops and Products, Volume 84, pp. 399–407

Leong, S.K., Lam, S.S., Ani, F.N., Ng, J.H., Chong, C.T., 2016. Production of Pyrolyzed Oil from Crude Glycerol using a Microwave Heating Technique. International Journal of Technology, Volume 7(2), pp. 323–331

Leung, D.Y.C., Wu, X., Leung, M.K.H., 2010. A Review on Biodiesel Production using Catalyzed Transesterification. Applied Energy, Volume 87(4), pp. 1083–1095

Maghami, M., Sadrameli, S.M., Ghobadian, B., 2015. Production of Biodiesel from Fishmeal Plant Waste Oil using Ultrasonic and Conventional Methods. Applied Thermal Engineering, Volume 75, pp. 575–579

Milano, J., Ong, H.C., Masjuki, H.H., Silitonga, A.S., Chen, W.H., Kusumo, F., Dharma, S., Sebayang, A.H., 2018. Optimization of Biodiesel Production by Microwave Irradiation-assisted Transesterification for Waste Cooking Oil-Calophyllum Inophyllum Oil via Response Surface Methodology. Energy Conversion and Management, Volume 158, pp. 400–415

Moser, B.R., 2009. Biodiesel Production, Properties, and Feedstocks. In Vitro Cellular Develop Biology Plant, Volume 45, pp. 229–266

Pandit, P.R., Fulekar, M.H., 2017. Egg Shell Waste as Heterogeneous Nanocatalyst for Biodiesel Production: Optimized by Response Surface Methodology. Journal Enviromental Management, Volume 198, pp. 319–329

Prakash Maran, J., Priya, B., 2015. Modeling of Ultrasound Assisted Intensification of Biodiesel Production from Neem (Azadirachta Indica) Oil using Response Surface Methodology and Artificial Neural Network. Fuel, Volume 143, pp. 262–267

Pereira, E., dos Santos, L.M., Einloft, S., Seferin, M., Dulius, J., 2015. Biodiesel Production from High FFA Degummed Rice Bran Oil by a Two-step Process using Ethanol/Methanol and a Green Catalyst. Waste and Biomass Valorization, Volume 6, pp. 343–351

Ramadhas, A.S., Jayaraj, S., Muraleedharan, C., 2005. Biodiesel Production from High FFA Rubber Seed Oil. Fuel, Volume 84(4), pp. 335–340

Said, N.H., Ani, F.N., Said, F.M.F, 2018. Emission and Performance Characteristics of Waste Cooking Oil Biodiesel Blends in a Single Direct Injection Diesel Engine. International Journal of Technology. Volume 9(2), pp. 238–245

Salaheldeen, M., Aroua, M.K., Mariod, A.A., Cheng, S.F., Abdelrahman, M.A., Atabani, A.E., 2015. Physicochemical Characterization and Thermal Behavior of Biodiesel and Biodiesel–diesel Blends Derived from Crude Moringa Peregrina Seed Oil. Energy Conversion and Management, Volume 92, pp. 535–542

Salamatinia, B., Mootabadi, H., Bhatia, S., Abdullah, A.Z., 2010. Optimization of Ultrasonic-assisted Heterogeneous Biodiesel Production from Palm Oil: A Response Surface Methodology Approach. Fuel Processing Technology, Volume 91(5), pp. 441–448

Satyanarayana, M., Muraleedharan, C. 2011. A comparative study of vegetable oil methyl esters (biodiesels).Energy , Volume 36, pp.2129–2137

Sebayang, A.H., Masjuki, H.H., Ong, H.C., Dharma, S., Silitonga, A.S., Mahlia, T.M.I., Aditya, H.B., 2017. Optimization of Reducing Sugar Production from Manihot glaziovii Starch using Response Surface Methodology. Energies, Volume 10, pp.1–13

Tse, H., Leung, C.W., Cheung, C.S., 2015. Investigation on the Combustion Characteristics and Particulate Emissions from a Diesel Engine Fueled with Diesel-Biodiesel-Ethanol Blends. Energy, Volume 83, pp. 343–350