Investigation of the efficiency of MWCNT-Mn3O4/Fe3O4/CeO2 catalyst in the treatment of meat processing plant wastewater with heterogeneous electro fenton process

In this thesis, it is purposed to remove COD from wastewater generated in meat processing industries with the Heterogeneous Electro Fenton process. MWCNT-Mn3O4/Fe3O4/CeO2 was used as Heterogeneous Electro Fenton catalyst. The catalyst was analyzed by XRD, FT-IR, XPS, Zeta potential and DLS, BET, SEM/EDX and TEM methods. The average particle size of the catalyst was determined as 4.5 nm and the zeta potential was determined as -22.84 mV. It was determined that the nanoparticles were decorated homogeneously on the MWCNT surface, but there were partial agglomerations. The chemical bond structures of the catalyst and valence electron states of the metal oxide nanoparticles were confirmed by FTIR and XPS analyses. The BET surface area of the catalyst was determined as 52.80 m²/g and the pore volume was determined as 0.103653 cm³/g. Numerical optimization of process conditions was achieved using the Response Surface Method (RSM) and model suitability was investigated. Regression coefficient (R2) of the quadratic model was found to be 0.9894. Actual values and predicted values were found to be close. It was concluded that the established model was reliable and meaningful (p<0.0001). Numerically optimized conditions were determined as pH 4.3, applied current 7.6 A, reaction time 83 min, and catalyst dosage 0.56 mg/L. Under optimum conditions, COD removal was found to be 92%. The energy consumption to remove 1 Kg of COD was 54.96 kW-h and the cost was found to be 8.68 $. In the studies that investigated of the catalyst effectiveness, the processes of Adsorption, Anodic Oxidation (AO) and AO-H2O2 showed the performance of COD removal as 25%, 68% and 78%, respectively. In the reusability experiments of the catalyst, it was observed that it exhibited high COD removal performance for 6 cycles and metal release was low. During six cycles, COD removal (%) was determined as 92, 88, 85, 82, 77 and 74, respectively and the experiment terminated at the end of the sixth cycle. Scavenging agent experiments were actualized under optimum conditions and ⦁OH was found to be the most effective responsible radical for oxidation. Good stability of the catalyst was determined using cyclic voltammetry technique (CV).