Integration of the adsorption and electro-oxidation process using 3D printed activated carbon monoliths for the degradation of pharmaceutical compounds

Abstract

A three-dimensional electrode reactor (3DER) was developed and evaluated for the degradation of recalcitrant pharmaceutical compounds such as diclofenac (DCF) and acetylsalicylic acid (ASA) from water, using for the first-time activated carbon monoliths (ACm) fabricated by 3D printing as a third electrode in the oxidation process. The degradation and mineralization percentages for the 3DER system were 81% and 74% respectively, which was up to 2.5 times higher than the system without using a third electrode. On the other hand, synergy calculations were performed, obtaining values of up to 35% when the integrated adsorption-oxidation technology was used compared to the degradations obtained by both processes sequentially. Operating parameters such as initial ACm saturation time (60 and 240 min) and applied voltage (0.6 and 0.9 V) were evaluated. Kinetic constants (kapp) were 3.2 times larger when the saturation time was shorter and the voltage higher. In addition, ACm regeneration tests were carried out to evaluate the regeneration of the material during the process, obtaining regenerations of up to 99%. Finally, the energy consumption by order of magnitude (EEO) was calculated for the best operating conditions in the 3DER, obtaining a value of 2.06 kWh/m3, which implies 50% less energy than the system without ACm. Despite the challenges in understanding the integrated processes in adsorption-electrooxidation, this study proposes compact and well-structured structures as an alternative for process optimization in 3DER.