Application of full factorial 23 design for optimization of glycerolysis reaction

Biodiesel is an established renewable source in the world and necessity of monitoring its quality becomes an important issue. Constituents can be analyzed by chromatographic techniques, using standards of monoacylglycerols (MAG), diacylglycerols (DAG) and triacylglycerols (TAG), which have a high acquisition cost due to its purity. Although, it is possible to synthesize significant volumes of MAG and DAG in order to obtain such standards in laboratory scale by glycerolysis reaction, which consists of the esterification of TAG in the presence of catalysts such as Ca(OH)2 and NaOH. This work aims to use a full factorial design approach (2³) with triplicate of central point – totalizing 11 experiments - to optimize glycerolysis reaction. The following variables were studied: (i) temperature (180°C and 230°C), (ii) reaction time (30 min and 60 min) and (iii) molar ratio glycerol/oil (2: 1 and 3: 1). The HPLC analyses were carried out according to the procedure described by ANDRADE, 20111. Effect of variables on MAG and DAG yield in glycolysis reaction are given in the Table 1. The Highest yields of DAG (53.67%) and MAG (46.20%) were obtained in the experiments 4 and 6, respectively. Estimation of coefficients of the model showed that variables of temperature and molar ratio have greater response influence. The temperature influences positively in the response, whereas the molar ratio influences negatively.