Photodegradation of emerging contaminant tetracycline using a zinc titanate nanocellulose composite as an efficient photocatalyst

Abstract

There is an urgent need to mitigate emerging contaminants, viz. pharmaceuticals, etc. In this work, efforts have been made to develop zinc titanate (ZnTiO₃)-based efficient photocatalysts to photodegrade tetracycline. Zinc titanates (ZnTiO₃) were synthesized by a simple sol–gel method. ZnTiO₃ was subjected to different calcination temperatures. In addition, a composite of carbon dot-doped zinc titanate and zinc titanate-cotton nanocellulose was also synthesized. The prepared samples were then characterized using UV-Vis spectroscopy, FTIR spectroscopy, X-ray diffraction (XRD), field-emission scanning electron microscopy (SEM), Raman spectrometry etc. The calcinated ZnTiO₃ at temperatures of 600 °C, 700 °C, 800 °C and 900 °C, carbon dot-doped calcinated ZnTiO₃ and ZnTiO₃-nanocellulose composites were examined for their photocatalytic activity in the degradation of tetracycline hydrochloride under light illumination. The photocatalytic studies demonstrated that ZnTiO₃ calcinated at 600 °C, carbon dot-doped ZnTiO₃ calcinated at 600 °C and the ZnTiO₃-nanocellulose composite show the highest photocatalytic activity of degradation of tetracycline hydrochloride under light illumination with degradation rates of 98.27%, 99.14%, and 99.81%, respectively. A pH-dependence study (pH 2–11) reveals that the photodegradation process does not depend on pH and the catalytic efficiency is not affected by different pH values. The study also involved investigating the active species that play crucial roles in the degradation process of tetracycline hydrochloride under light illumination. It was observed that holes and superoxide ions play pivotal roles in the degradation of tetracycline hydrochloride. Such studies help in finding solutions for mitigation of emerging contaminants.