Biodiesel production from tucumã (Astrocaryum aculeatum Meyer) almond oil applying the electrolytic paste of spent batteries as a catalyst

Abstract

Improper disposal of batteries can cause several environmental problems. Thus, this work aimed to apply the electrolytic paste (SB) of spent AA batteries as a catalyst. The SB was heat-treated (400 and 800 °C) and characterized by FTIR, XRF, XRD, TGA, SEM-EDX, titratable acidity, and soluble alkalinity. Although the thermal treatment changed the constituent phases, a majority presence of manganese and zinc was observed in the materials. The extracted tucumã almond oil was also characterized, showing a high percentage of saturated fatty acids (75%) and high acidity (9.25 KOH/g oil). The untreated SB showed higher acidity (0.02 mmol/g) and, consequently, higher catalytic activity in transesterification reactions, resulting in good conversions (>97%). Temperature and reaction time were the most significant parameters, according to ANOVA. SB also showed high catalytic activity in the esterification of oleic acid, achieving good conversions (96%). Thus, the electrolytic paste proved to be a potentially efficient and eco-friendly catalyst for biodiesel production, even from highly acidic oils.