Effects of residue and antioxidant on thermo-optical properties of biodiesel.

Thermal lens (TL) spectrometry was applied to soybean biodiesel samples, in order to assess the behavior of their thermo-optical properties during the preparation before and after the washing process. The study was based on the thermal diffusivity parameter, which is highly sensitive and is related to the chemical composition of the sample. The results showed a difference of approximately 20% between the initial (unwashed) and the final (washed) steps of biodiesel production. This behavior indicates that the residue of the biodiesel production influences the thermal diffusivity value. Consequently, TL spectrometry can be a useful methodology for certifying the quality of biodiesel during production.