Synthesis of Activated Carbon-Supported Catalysis Systems and Research for Electrocatalytic Performance on Wastewater Treatment

Abstract

Electrochemical oxidation methods are simple, use very few extra reagents, and are both technically and economically viable technologies that can be used for the treatment of various industrial effluent streams including olive wastewater. The treatment is based on the direct anodic oxidation method in which the pollutants are adsorbed on the anode surface and then reduced by the electron transport reaction. In this study, the effect of different catalysts on the treatment of olive wastewater is carried out by using electrocatalytic methods. Initially, TiO2/AC, V2O5/TiO2/AC, WO3/TiO2/AC, and V2O5/WO3/TiO2/AC catalysts were prepared by a sol-gel method. Then, the removal of different pollutants such as color, phenol, lignin, and Chemical Oxygen Demand (COD) was investigated by using different experimental electrochemical processes. In the electrocatalytic oxidation process, synthesized catalytic materials were used as particle electrodes (working electrodes) with the graphite electrodes in an electrochemical cell. The treatment process was optimized by investigating the effects of different parameters, for example, treatment time, catalyst type, catalyst amount (as solid/liquid ratio), voltage, the amount of supporting electrolyte (NaCl), and suspension’s pH. The V2O5/TiO2/AC catalyst exhibited the highest percentage of removal under all experimental conditions, with a significant effect of voltage on the removal capacity observed (82.95% for lignin and 74.42% for COD). While the pH effect showed limited influence on the removal performance, higher yields were observed in acidic conditions. The electrocatalytic reaction involves various steps such as adsorption, nano adsorption, electrooxidation, and electrocatalytic oxidation. The individual effects of these steps were also investigated, resulting in percentage color removals of 25.58%, 51.72%, and 72.42%, respectively. When the data were evaluated in terms of kinetics, it was seen that the data provide a first-degree agreement of over 90 % in all experimental parameters and the removal rate constants of low molecular weight substances may generally be higher than the others. Despite its significant lignin removal efficiency, the catalytic process mentioned above yielded lower values compared to other catalytic methods. Additionally, it was observed that the phenol concentration increased as a result of this process. This suggests that for the catalytic oxidation of olive wastewater effluent, the preliminary treatment using an electrocatalytic process is found to be more effective. The synergistic combination of these processes was more effective than the individual process.