TiO2 Nanotube-Based Sensor for the Detection of Cyanide in Water

Abstract

Cyanide is an acutely toxic compound capable of spreading to ground and surface waters more easily than other industrial contaminants. Real-time monitoring of cyanide concentrations calls for a robust and quick method for cyanide detection in water. This work focuses on the application of anodized titanium dioxide (TiO2) nanotubes as a substrate, with suitable and relatively inexpensive additives, for the sensitive and selective electrochemical detection of cyanide in water. The TiO2 nanotubes were modified by the addition of iron (Fe) and sulfur (S) as sensing elements. Characterization of the prepared sensing platform was performed using X-ray diffraction and electron microscopy. Current-time measurements indicated that i) increasing cyanide concentration can perturb the current proportionally, ii) the differential in the current can be used as a calibration for quantitative detection of cyanide, and iii) the sensor is highly selective even in the presence of interfering species. A cyanide detection limit of 0.49 μM and a sensitivity of −13.8 mAcm−2 μM−1 were established. The sensor response indicated that an Fe-S-TiO2 nanotube sensing electrode could effectively and repeatedly be used over a period of several months for the sensing of cyanide concentrations lower than the recommended WHO and USEPA limits in water.