Otimização de misturas ternárias de diesel, biodieseis de crambe e de óleo de fritura via metodologia de superfície de resposta

Abstract

The present study aimed to produce and characterize blends of S10 diesel and biodiesels from crambe oil and waste cooking oil, using a ternary system and response surface methodology as the experimental design. The physicochemical properties of viscosity, density, and calorific value were analyzed, seeking the optimization of these variables to enable the application of the biofuels in internal combustion engines. The biodiesel was obtained through a transesterification reaction with methanol and potassium hydroxide as a catalyst. The choice of feedstocks was based on environmental and economic viability: waste cooking oil, as an easily accessible and low-cost residue, and crambe oil, as a non-edible crop with no competition with food production. For the procedure, seven blends were prepared with different proportions of crambe biodiesel, waste cooking oil biodiesel, and S10 diesel, according to the ternary system design. Characterization via infrared spectroscopy and thermogravimetric analysis confirmed the formation of esters and the thermal stability of the biodiesels. The response surfaces were generated using Chemoface software to identify the optimal blend proportions. The results indicated that viscosity and density increase with higher biodiesel fractions in the mixtures, while the calorific value decreases. Among the experimentally obtained blends, the best alternatives to diesel fuel were: 50% diesel and 50% waste cooking oil biodiesel for viscosity, and 50% diesel and 50% crambe biodiesel for density and calorific value. The statistical model used showed a high degree of fit (R² > 0.97), validating the efficiency of the experimental design. It is concluded that the production and use of blends with crambe and waste cooking oil biodiesels are feasible. The applied methodology allowed the identification of suitable proportions for optimizing the desired properties, highlighting the potential of these sources as sustainable alternatives to fossil diesel.