Uncovering fabrication approach impact on photocatalytic ciprofloxacin (CIP) antibiotic degradation of brookite TiO2

Solar-driven antibiotic degradation by semiconductor photocatalysis technique offers a promising route to tackle with the environmental issue we are currently facing. Herein, three kinds of brookite TiO₂, TiO₂-Glycerol (GL)/NaOH (OH⁻), TiO₂-Ethylene glycol (EG)/Ethylenediamine (EDA), and TiO₂- Ethylene glycol (EG)/NaOH (OH⁻), are prepared by changing fabrication approaches from as-prepared two different Ti-polyol precursors. The composition and structure of the above brookite nanocrystals is studied in detail, and the effects of different synthesis methods on their optical properties, surface areas and wettability, and photocatalytic degradation activities are discussed. The photocatalytic ciprofloxacin (CIP) remediation evaluation shows that the TiO₂-EG/EDA enriched amine group confirmed by FTIR and XPS measurements has the highest dark adsorption as well as subsequent photocatalytic degradation activities compare with the other two types of brookite. Subsequently, the unveiling on how the TiO₂-EG/EDA effectively degrades the CIP molecules is achieved. Indeed, on the basis of a series of characterizations, the good CIP adsorption capacity resulted from the weakest hydrophilicity, the largest specific surface area, the unique chemisorption effect by surface amine group, combining with the smallest band gap, the fastest photogenerated charge transport speed, the longest photogenerated electron lifetime and the most active sites, contribute to the rapid degradation of CIP upon the TiO₂-EG/EDA. In addition, the CIP degradation pathway is proposed by HRMS analysis, and the EPI suite program predicts the intermediate molecules have no biotoxicity for the environment. It is expected this work could provide useful reference for highly-efficient photocatalytic antibiotics-degradation in terms of experimental design and materials fabrication.