Treatability of biodiesel wastewaters by using KMnO4 and KMnO4/O3 processes and kinetic analysis

Abstract

Abstract This study aims to investigate the treatability of electrocoagulated biodiesel wastewater (ECBD) by KMnO4 and KMnO4/O3 processes. The ECBD removal efficiencies of both KMnO4/O3 and KMnO4 methods were compared, and the COD and MeOH removal efficiencies with the KMnO4/O3 process gave better results than the KMnO4 process. For the ECBD removal efficiencies, the experimental parameters including pH, KMnO4 dose, O3 dose and reaction time were optimized by changing one parameter at a time. As a result of 6 h of KMnO4 oxidation, 91.74% of COD and 95.93% of MeOH removal was achieved under the optimum conditions. However, the COD and MeOH removal efficiencies have been obtained under optimum conditions for KMnO4/O3 as 97.79% and 98.30%, respectively. The second-order kinetic model has been found to be the most suitable model for both processes and the R2 has been found as 0.999 and 0.999 for KMnO4 and KMnO4/O3, respectively. The reaction k has also been calculated as 6 × 10−5 L·mg−1·min−1 and 1.63 × 10−4 L·mg−1·min−1 for COD and MeOH in KMnO4 oxidation, respectively. Furthermore, the k has also been calculated as 6 × 10−5 L·mg−1·min−1 and 1.6 × 10−4 L·mg−1·min−1 for COD and MeOH in KMnO4/O3 oxidation, respectively.