Toward combined photo-electrochemical system for degradation of ceftriaxone contaminated water over Ti-based mixed metal oxide photoanodes performance evaluation and mechanism insights

Abstract

Background

As a growing environmental concern over the accumulation of antibiotics in aquatic environmets, the development of an efficient degradation process has been addressed. In this study, the application of the photo-electrochemical oxidation (PEO) process for the degradation of ceftriaxone was evaluated.

Methods

Experiments were performed in an undivided cell equipped with Ti/IrO₂ (0.1)-Ta₂O₅ (0.1)-TiO₂ (0.8) and Ti/IrO₂ (0.2)-Ta₂O₅ (0.2)-TiO₂ (0.6) as anodes and Platinum (Pt) sheet as the cathode of the degradation process. Anodes were characterized using scanning electron microscopy (SEM), mapping energy dispersive X-ray (EDS-mapping), ultraviolet–visible diffuse reflectance spectroscopy (DRS), and atomic force microscopy (AFM). Cyclic voltammetry (CV) and photocurrent analysis were performed to consider the photo-electrochemical behavior of anodes. The effect of operational parameters, including initial pH (3–9), ceftriaxone initial concentration (C = 10–50 mg L⁻¹), current density (I = 100–500 mA cm⁻²), and Na₂SO₄ as electrolyte concentration (C_electrolyte = 0.05–0.25 mg L⁻¹) on ceftriaxone removal efficiency were determined.

Significant findings

Outcomes of experiments revealed that under optimum conditions (pH = 6, C = 30 mg L⁻¹, C_electrolyte = 0.1 mg L⁻¹, and I = 300 mA cm⁻²), 98.6 % of degradation efficiency was achieved. The combined process resulted in 77.6 and 69.3 % total organic carbon removal of ceftriaxone on Ti/IrO₂ (0.1)-Ta₂O₅ (0.1)-TiO₂ (0.8) and Ti/IrO₂ (0.2)-Ta₂O₅ (0.2)-TiO₂ (0.6) after five hours of PEO process, respectively. Additionally, the feasible intermediates of ceftriaxone degradation were identified using Gas chromatography-mass spectroscopy (GC-MS) analysis.