BIODIESEL OF WASTE OIL AND MORINGA OIL (MORINGA OLEIFERA): A KINETIC AND THERMAL ANALYSIS

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1 BIODIESEL OF WASTE OIL AND MORINGA OIL (MORINGA OLEIFERA): A KINETIC AND THERMAL ANALYSIS Kelvin Costa de Araújo 1, Samuel Guedes Bitu 1, Tathilene Bezerra Mota Gomes Arruda 2, Francisco Eduardo Arruda Rodrigues 1, Nágila Maria Pontes Silva Ricardo 2, Antonio Gouveia de Souza³, Manoel Barbosa Dantas Instituto Federal da Paraíba - IFPB, Curso de Licenciatura em Química, Campus Sousa, CEP , Sousa-PB, Brasil. 2. Universidade Federal do Ceará - UFC, Departamento de Química Orgânica e Inorgânica, Campus do Pici, Bl 940, CEP , Fortaleza-CE, Brasil. 3. Universidade Federal da Paraíba, Departamento de Química, Centro de Ciências Exatas e da Natureza (CCEN), Campus I, , João Pessoa-PB, Brasil. ABSTRACT The biodiesel obtained from waste cooking oil (BEF) and its blend with moringa biodiesel (BEM) (Moringa oleífera) was submitted to kinetic analysis by the thermogravimetric data. It was used 10 (BFM10) and 20% (BFM20) blend of the waste cooking oil biodiesel with moringa oil biodiesel and the thermogravimetric analysis was performed in three different heating rates (10, 20 e 30 C/min). The integral method of the resolution of the Arrhenius integral temperature for the determination of the apparent kinetic parameters was utilized. The methods of Coats-Redfern and Madhusudanan were used for the kinetic study. The R2 model was suggested as the apparent kinetic for the BEF, BFM10 and BFM20 samples. This kinetic is based in a determinant step in the limitrophe phase. The F1 model was suggested as the apparent kinetic for the BEM sample. This model is based in the reaction order. The values of the apparent activation energy were KJ/mol for BEF, 73.84KJ/mol for BFM10, 66.6 KJ/mol for BFM20 and KJ/mol for BEM (average of the obtained values). INTRODUCTION The use of the biodiesel as an energetic resource showed itself as an alternative for the use of non-renewable of fossil fuels, as petroleum, natural gas or coal. Beyond the maintenance of the carbon cycle, the use of the biodiesel affords the reduction of the polluter substances emission. These substances cause acid rain or damage to the ozone layer and its reduction has a beneficial effect in the environment, by the use of the biodiesel. The biodiesel is obtained by the transesterification of the oils and fats and its characteristics are largely studied. There are three biodiesel generations: the first corresponding to the biodiesel obtained by the transesterification of the edible oils, the second corresponding to the biodiesel obtained by the transesterification of the nonedible oils and the third to the biodiesel obtained by the transesterification of seaweed [1]. Moringa oleifera is an example of oleaginous. It belongs to the Moringaceae family and occurs in Northeast of Indian, Africa, Arabia, Asia, Pacific and Caribbean islands and South America [2] and it shows a good option for the biodiesel production [3]. Despite it not being used in industrial scale, due to the difficulty of the oil extraction in large scale, a study with a pilot-plant of oil extraction with carbon dioxide like super critic fluid is related and differences between the oil obtained by this process and oils obtained by conventional methods are not found [4]. Researches relate the optimization of the reactional conditions for the moringa oil alkaline transesterification [5] and the

2 behavior of the biodiesel and its blend with diesel in engine [6]. Another good option for the biodiesel production is the reuse of the waste cooking oil, due to its low cost, as well as a solution for its disposal and the potential contamination caused by this waste. Researches cite the obtaining of the waste cooking oil biodiesel and the dioxide emission by its combustion [7] and the behavior observed was similar to the other biodiesels. The waste cooking oil needs an initial treatment for the removal of the solid impurity and water. For the reduction of the free fatty acids concentration, techniques like the acid transesterification, the neutralization by the use of the alkaline solutions and posterior removal by decantation, extraction of the free fatty acids by the use of polar liquids or the distillation of the free fatty acids are suggested [8]. In the present work, the kinetic analysis by the thermogravimetric data for waste cooking oil biodiesel and its blend with moringa biodiesel are related. For the study, the Coats-Redfern [9] and Madhusudanan [10] methods were used which are integral methods for the resolution of the Arrhenius temperature equation and there was not the supposition of the specific kinetic model free methods. EXPERIMENTAL METHOD The waste cooking oil used in the experiment was obtained by a collection realized by undergraduate students in chemistry of the Federal Institute of Paraíba Campus Sousa and the moringa oil was obtained by Sohxlet extraction of the moringa seeds. These seeds were collected in the São Gonçalo region, Paraíba state, Brazil. Like the waste cooking oil was submitted to thermic stress, its acidity was unsettled. For the correction, to avoid the undesirable saponification during the transesterification reaction, BF100 was neutralized by washing with potassium hydroxide (Synth, purity degree 85%) 10%. The oils were transesterified by homogeneous basic catalysis, in the presence of the ethyl alcohol (Synth) and potassium hydroxide (Synth, purity degree 85%) as a catalyst. The reactional conditions were: one hour for the reaction, continuous agitation and ambient temperature; ethyl alcohol 30wt% and 1.5wt% of catalyst, both in relation of the weight of the oil. The blends (BFMX) of the waste cooking oil biodiesel and the moringa biodiesel were prepared by the addition of 10 and 20% (v/v) of BEM in BEF, and the blends were named BFM10 and BFM20. The BEF, BEM, BFM10 and BFM20 samples were submitted to thermogravimetric analysis. Thermogravimetric curves were obtained using a simultaneous TG/DTG analyzer (Q50 V20, TA Instruments) in synthetic air, in the C temperature range at a heating rate of 10, 20 and 30 C/min. RESULTS AND DISCUSSION Figures 1 to 4 correspond to the TG curve of the samples in oxidative atmosphere. The TG curve showed decomposition in one step correlated to the pyrolysis of the esters. Like the initial temperature of the degradation of the samples was higher than 100 C, the possibility of water presence in the samples was excluded. By the study of the thermogravimetric data, it was observed that the increase in the heating rate did not affect the temperature range for the thermal events analyzed. The initial temperature of degradation for BEM was higher than observed in thermogravimetric data of the BEF, but the addition of the moringa biodiesel did not change significantly the thermogravimetric degradation behavior of the waste cooking oil biodiesel, for the

3 percentage used in the study. The temperature range and the peak temperature of the thermal events observed in the experiments are compiled in the Table 1. Table 1 Temperature range and peak temperature for the thermic events observed. Temperature ( C) 10 C/min 1 thermal event BEF BEM BFM10 BFM Tpeak C/min thermal event Tpeak C/min thermal event Tpeak Fig. 1 TG curve for BEF. Fig. 2 TG curve for BFM10. Fig. 3 TG curve for BFM20. Fig. 4 TG curve for BEM.

4 The kinetic analysis was realized by the use of the Coats-Redfern and Madhusudanan methods. These methods are mathematical treatment of the Arrhenius equation and they are classified as a model-free method, since in the treatment of the thermogravimetric data by the equations, several kinetic models are tested and the model that gives the linear correlation most near for the unity is selected, for the determination of the kinetic parameters. It is important to emphasize that the parameters determined are considered apparent, since the mathematical development for these methods is based on degradation reactions for solids, although these concepts have been used in the fuels analysis with success [12-14]. The apparent kinetic found was the same for the BEF and its blends, a R2 model. This model is based in a bidimensional geometric model, and the reaction occurs in limitrophe phase and it has cylindrical symmetry. For the BEM sample, the pseudo-kinetic model F1 was suggested. This model is based in the order of the reaction, in the case, a first order reaction. It was observed that the addition of the moringa biodiesel did not affect the kinetic properties of the waste cooking oil biodiesel. The value of the energy activation for BEF obtained was higher than obtained for BEM, and the kinetic behavior of the blends was similar to observed for BEF. The parameters values obtained by the Coats-Redfern and Madhusudanan methods are compiled in Table 2. Table 2 Kinetic data from BF100, BF10 and BF20 obtained by Coats-Redfern and Madhusudanan integral methods. Coats-Redfern Madhusudanan BEF 10 C/min Ea (KJ/mol) A (s -1 ) 5.68 x x 10 6 R C/min Ea (KJ/mol) A (s -1 ) 6.49 x x 10 6 R C/min Ea (KJ/mol) A (s -1 ) 1.88 x x 10 6 R BEM 10 C/min Ea (KJ/mol) A (s -1 ) 2.42 x R C/min Ea (KJ/mol) A (s -1 ) 8.38 x x 10² R C/min Ea (KJ/mol) A (s -1 ) 1.80 x x 10³ R BFM10 10 C/min Ea (KJ/mol) A (s -1 ) R x 10 7

5 20 C/min Ea (KJ/mol) A (s -1 ) R x x C/min Ea (KJ/mol) A (s -1 ) R x x 10 6 BFM20 10 C/min Ea (KJ/mol) A (s -1 ) 4.4 x x 10 5 R C/min Ea (KJ/mol) A (s -1 ) 4.09 x x 10 5 R C/min Ea (KJ/mol) A (s -1 ) 1.94 x x 10 5 R CONCLUSION The thermogravimetric analysis of the waste cooking oil ethyl biodiesel showed degradation in one step, corresponding to the pyrolysis of the esters. The initial temperature of the degradation the samples occurred above 100 C and the presence of water in the samples was excluded. The initial temperature of the degradation for BEM was higher than observed for BEF, but the blends formed by the mixture between BEM and BEF had behavior similar to BEF, for the percentages evaluated in this research. The increase of the heating rate did not affect the thermogravimetric behavior of the samples. The thermogravimetric data allowed the determination of the apparent kinetic parameters, like the activation energy and pre-exponential factor. As observed in the thermograms, the values of the activation energy found in BEF were not affected by the addition of the BEM. The pseudo-kinetic observed was the same for the BEF, BFM10 and BFM20 samples, corresponding to R2 model, and for the BEM the model found was F1. The values of the activation energy obtained for the samples were similar to the values related for the others biodiesel samples in the literature [12, 15-16]. REFERENCES 1 M. Tariq, S. Ali, N. Khalid. Activity of homogeneous and heterogeneous catalysts, spectroscopy and chromatographic characterization of biodiesel: a review. Renew. Sust. Energy Rev. 2012; 16: J. F. Morton. The horseradish tree, Moringa pterygosperma (Moringaceae) a boon to Arid Lands?. Econ. Bot. 1991; 45: U. Rashid, F. Anwar, B. R. Moser, G. Knothe. Moringa oleifera: a possible source of biodiesel. Bioresour. Technol. 2008; 99: K. Ruttarattanamongkol, S. Siebenhandl-Ehn, M. Schereiner, A. M. Petrasch. Pilot-scale supercritical carbon dioxide extraction, physico-chemical properties and profile characterization of Moringa oleifera seed oil in comparison with conventional extraction methods. Ind. Crops Prod. 2014; 58:68-77.

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