ATR-FTIR AND UV-VIS AS TECHNIQUES FOR METHANOL ANALYSIS IN BIODIESEL-WASHING WASTEWATER

Methanol present in wastewater from the biodiesel industry can become an atmospheric pollutant and an environmental liability of effluents. This article proposes the development and performance evaluation of two spectroscopic methods, ATR-FTIR and UV-Vis, to identify and quantify methanol in aqueous media. The results of both ways exhibited remarkable linear detection, with a coefficient of determination (r2) > 0.99, wide working range, and relative standard deviation (RSD) < 12%. In the ATR-FTIR method, the detection and quantification limits were 0.064 and 0.128% m V-1, respectively. The UV-Vis method presented lower limits (0.005 and 0.008% m V-1, respectively). Finally, the methods were successfully applied to quickly and sensitively quantify the methanol present in wastewater from biodiesel-washing in a wide concentration range of 0.008-0.641% m V-1. Therefore, we evidenced the feasibility of spectroscopic methods in quality control for identifying and quantifying methanol in aqueous solution, with potential for application in biodiesel production industries and research laboratories. Mainly by ATR-FTIR, in the region of 1300-900 cm-1, as it proved to be more environmentally friendly, faster, and cheaper than the GC-FID method.