Investigating the Efficiency of the VUV/H₂O₂ Process in Removing Tetracycline from Aqueous Solutions

Abstract

Background: This study investigates the efficiency of the advanced oxidation process VUV/H₂O₂ for removing the antibiotic from tetracycline (TC) aqueous solutions. Methods: The process uses a low-pressure vacuum ultraviolet (VUV) lamp emitting at 185 nm and 254 nm to degrade TC. The addition of hydrogen peroxide (H₂O₂) enhances the generation of hydroxyl radicals (OH•), which are the main agents responsible for the degradation. Various operational parameters were evaluated, including pH (5-7-9), initial TC concentrations (5, 10, and 20 mg/L), H₂O₂ concentrations (1 - 10 mg/L), as well as the presence of anions and organic compounds. Results: Results showed that the highest removal efficiency of TC (100%) was achieved at pH 7 with 2 mg/L of H₂O₂ after 90 minutes of treatment. Increasing the H₂O₂ concentration beyond the level of 10 mg/L reduced the efficiency slightly to around 90.55% due to scavenging effects. In the absence of H₂O₂, the VUV process alone removed about 60% of TC. The presence of anions such as phosphate, chloride, and sulfate led to decreases in removal efficiency by 29.4%, 13.4%, and 15.6%, respectively. Among the tested organic compounds, phenol and humic acid exhibited the most pronounced inhibitory effects. The degradation kinetics followed a pseudo-first-order model (R² = 0.9942), indicating a consistent and predictable reaction behavior. Under optimal conditions, the removal efficiencies of chemical oxygen demand (COD) and total organic carbon (TOC) were 78% and 40%, respectively. Conclusions: In conclusion, the study demonstrated that the VUV/H₂O₂ process is an effective and tunable method for the degradation and mineralization of TC in contaminated water.