Electric Field as a Useful Tool to Improve the Poor Adsorption Affinity of Pollutants on Carbonaceous Aerogel Pellets

The removal of ionisable drugs (fluoxetine, sulfamethizole and antipyrine) from aqueous solution was performed by conventional adsorption process using carbonaceous aerogel pellets as adsorbents. Despite more than 96% elimination was achieved for sulfamethizole and antipyrine after 1440 min, only 2.5% fluoxetine removal was detected at the same time. Under a multicomponent system, the presence of these three pharmaceuticals in the solution involves fivefold depletion on the total adsorbed quantity showing a competitive behaviour for the linking points and the interference due to the presence. Therefore, the authors have proposed the use of electric field on the traditional adsorption process to enhance the poor affinity of fluoxetine to the aerogel and improve the competitive adsorption of the other compounds. Specifically, the electrosorptive removal of fluoxetine was examined applying different voltages ranging from 0.8 to 1.3 V, achieving maximum adsorption at 1.2 V. The application of electric field provokes the formation of an instantaneous electric dipole due to the polarization of the 3D electrode material and consequently, increasing the affinity of the pollutants towards the aerogel pellets. After demonstrating the applicability of the electrosorption on fluoxetine removal, the effect of the water matrix was analysed on the process. For that purpose, the removal of these ionisable drugs was evaluated using several real wastewaters, in particular, incoming raw sewage and effluents after primary and tertiary treatment collected from an urban wastewater plant. As was expected, the contaminant decay was slightly lower due to the complexity of the water matrix. Total pollutants removal only was achieved using the outgoing-treated water as matrix due to the minimal competitive adsorption. Finally, Microtox® test confirmed the excellent ability of this approach for removing these pharmaceuticals leading to a luminescence inhibition was declined around 60-80% as a function of the water matrices compared to the polluted influent