Visible light photocatalytic degradation of amitriptyline using cobalt doped titanate nanowires: Kinetics and characterization of transformation products

Abstract

Pharmaceutical compounds have been frequently detected in environmental matrices such as effluents, surface water and drinking water which is a matter of concern. Because of this, the use of photocatalysis has been highlighted as a promising way to remove these contaminants from water systems and several photocatalysts have been developed for this purpose. In this study, cobalt-doped titanate nanowires (Co-TNW) were used as a catalyst for the degradation of amitriptyline (AMI), an antidepressant drug, under visible light radiation. The kinetic was monitored and additionally, the transformation products (TPs) were elucidated by high-resolution mass spectrometry. During photolysis, the AMI did not degrade in distilled water, but was degraded in tap water, in other words, the matrix influenced the degradation. And in photocatalysis, the degradation rate was almost twice as high as photolysis. As a result of the photocatalytic degradation process, nine TPs were generated and their degradation pathways were proposed. Three of these TPs have never been described in the literature. Overall, the TPs demand additional time under radiation to be eliminated, which shows that their formation may be relevant for toxicity and photodegradation studies.