Low-cost biodiesel characterization by a machine-vision system and laser-induced fluorescence

In this work, a low-cost fluorescence machine-vision system was implemented for biodiesel samples characterization without the necessity of using a spectrometer. Biodiesel was produced from fresh oil around the critical temperature of methanol, using an acidic zeolite as a catalyst. The methanol / oil ratio and the amount of catalyst were also varied. Biodiesel yields ranged from 83 to 95% with dynamic viscosities from 27.7 to 7.5 cP. The reaction products contained more than 82% wt.% of methyl esters, producing a biodiesel of acceptable quality that is monitored by a low-cost characterization method. Our results indicate that a higher content of triglycerides in biodiesel (low conversion of vegetable oil) gives a higher intensity of visible fluorescence, which was also notably observed in corn oil and oleic acid. Contrary, methyl oleate gives the lowest fluorescence intensity. Thus, it can be determined that a good biodiesel made up of a mixture of methyl esters will provide a fluorescence emission of medium intensity in contrast to the reference samples.