From all the contaminants of biodiesel, metals have received special attention due to the acceleration of biodiesel degradation processes. Aiming reduce the generation of wastewater or residual solvents, the present study objective to evaluate the use of murumuru kernel shell as a bioadsorbent for removal of contaminants Na, K, Ca, Mg, Cu and Fe from crude soybean biodiesel – produced by homogeneous catalysis with KOH – and compare the results with conventional purification using deionized water. To obtain the bioadsorbent, murumuru kernel shell was crushed, sieved and kiln dried. The material was characterized by thermogravimetric analysis (TG) for determine the thermal profile and energy dispersion X-ray spectroscopy, for chemical composition (EDX). The crude biodiesel was separated from glycerol phase by decantation, and purified via wet (deionized water to 80 °C) and dry purified with murumuru adsorbent (3% w/v, at room temperature for 30 min). Determination of metallic contaminants before and after the purification processes was done by MIP-AES. The TG analysis revealed that the material remains stable at the employed temperature. The EDX analysis revealed SiO2 (37.2%) and CaO (33.1%) as major components, responsible for the high adsorptive capacity of metallic components (FOLETTO et al., 2020). ANP Resolution N° 45 (2014) establishes a maximum limit of 5 mg kg-1 for Na+K and Ca+Mg. For Ca and Mg, no significant levels were found in all investigated samples. For the other components, dry purification with murumuru bioadsorbent were better than purification with deionized water, since it was able to remove practically all contaminants investigated, while the water purification did not meet the limits established for Na and K. Thus, the use of murumuru kernel shell as bioadsorbent is an effective alternative for purification of crude biodiesel, enabling the reuse of this agro-industrial waste.

FOLETTO, Edson Luiz et al. Química Nova, v. 28, n. 6, p.1055-1060, 2005.