Caracterização físico-química do efluente da produção de biodiesel e tratamento eletroquímico usando ânodo de Ti/IrO2-Nb2O5

Abstract

This work shows the study of the electrochemical treatment of wastewater from biodiesel production using Ti/IrO2-Nb2O5 anodes. Initially, the wastewater was characterized by physical-chemistry analysis as pH, conductivity, color, turbidity, alkalinity, oils and greases, solids, COD, glycerin and methanol. The electrodes of Ti/IrO2-Nb2O5(60:40%) was manufactured and characterized by scanning electronic microscopy (SEM), X-rays diffractions (XRD), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and accelerated stability test (AST). The electrochemical treatment was evaluated by varying the current densities of 25; 50; 100 and 150 mA cm-2 for 4 hours and one exhaustive electrolysis at 150 mAcm-2 for 8 hours. The efficiency of electrochemical treatment was monitored by analysis of total organic carbon (TOC) and Uv-Vis spectroscopy analysis in pre-established times during the electrolysis. In spite of this, ecotoxicity tests with V. fischeri for the wastewater samples before and after the electrochemical treatment were performed. The main results obtained in this work showed that the electrochemical treatment with Ti/IrO2-Nb2O5 (60:40%) leads to 79% of removal of TOC, with application of 150 mA cm-2 for 8h. However, the ecotoxicity tests showed a significant increase of toxicity of the wastewater after the electrochemical treatment at 150 mA cm-2 for 8h. This increased of toxicity could be related to formation secondary products in the electrochemical treatment, as evidenced by UV-Vis spectra.