Determination of the optimum conditions for electrochemical regeneration of exhausted activated carbon

Abstract

In this study, the electrochemical regeneration of activated carbon used to soften the mains water in the batch system was investigated. The experimental data obtained were used to test the Freundlich and Langmuir isotherm models and it was seen that the experimental results showed good agreement with the Langmuir isotherm. To determine the optimum conditions; electrolyte type, electrolyte concentration, current density, electrolyte pH and regeneration time parameters were optimized. To evaluate the performance of activated carbon after electrochemical regeneration, adsorption tests with methylene blue (MB) were performed. The best removal efficiency was obtained with 0.1 M NaBr, 50 mA/cm2, 13 g activated carbon (AC) and 200 mL electrolyte volume. In the research, Sn/Sb/Ni-Ti cube was chosen as the anode and Pt/Ti as the cathode. After the ideal conditions for the electrochemical regeneration of AC were determined, the adsorption-regeneration cycle was carried out. As a result, it has been found that AC can be effectively recycled up to 6 times. While the removal efficiency was 98.78 % after the first cycle, the removal efficiency was calculated as 68.55 % in the last cycle. In addition, 1.3 kWh/kg electrical energy consumption was obtained under optimum conditions in the research.