TiO2@C nanostructured electrodes for the anodic removal of cocaine

Abstract

The generalization use of therapeutic and illicit drugs are introducing new several chemical pollutants in water. They have been detected in water and sewage samples worldwide, hence they are considered as emerging pollutants. The increase of water threats has a negative impact on the life quality and human health. Among the illicit drugs, cocaine and derivatives are increasingly present, making efficient detection and elimination of wastewater highly prioritaire. In that sense, the main core of this work is the assessment of a novel cost-efficient electrochemical method based on substrate electro-oxidation (EO) using low-cost anodes based on common graphite modified with TiO2 nanosized particles incorporated on the surface by assisted microwave deposition. Two different diameters (2 and 5 nm) of nanostructured TiO2@C anodes were tested for cocaine EO reaction using three different electrolytic solutions (NaCl 50 mM, Na2SO4 50 mM or Na2SO4 100 mM). In all cases, the electrochemical oxidation of cocaine appears to be a combination of hypsochromic and hyperchromic processes. Reaching ca. 90 % degradation after 10 minutes for all electrodes, an enhanced efficiency was especially observed for the system with higher cylindrical diameter and NaCl salt medium. The differential pulse (DP) voltammogram, carried out with all assay solutions after 10 minutes of anodic remediation at both electrodes, exhibited an anodic peak consistent with catechol like compounds.