Photodegradation of ciprofloxacin using an alginate/TiO2 hydrogel for water remediation

The presence of antibiotics in aquatic environments has contributed to the emergence of multi-resistant bacteria, which can pose significant risks to human health through contaminated drinking water and food. These antibiotics enter water bodies primarily due to inefficient wastewater treatment and inadequate disposal practices in hospitals, pharmaceutical industries, and households. Therefore, the development of efficient water decontamination methods, such as adsorption and photodegradation, is crucial to mitigate water pollution. In this study, a photocatalytic hydrogel composite based on sodium alginate and TiO₂ was developed for the degradation of ciprofloxacin (CIP) in water. The hydrogel composite was characterized using various analytical techniques, including scanning electron microscopy, energy-dispersive X-ray spectroscopy, Fourier-transform infrared spectroscopy, and thermogravimetric analysis. To optimize the CIP degradation process, a fractional factorial design (2k⁵⁻²) was employed, which identified TiO₂ concentration, hydrogel dosage (g), and UV lamp distance as the most significant factors influencing degradation efficiency. The hydrogel composite's performance was assessed under varying pH conditions and CIP concentrations. Complete degradation of CIP was achieved after 300 minutes of UV exposure. Additionally, a recyclability study demonstrated the hydrogel's stability over three cycles, with 100 % CIP removal efficiency maintained in each cycle. Notably, the adsorption capacity increased from 10 % in the first cycle to 31 % in the third cycle, which may be attributed to increased porosity of the hydrogel matrix following photodegradation. • Sodium hydrogel beads loaded with TiO2 efficiently degrade ciprofloxacin. • Adsorption – photocatalysis showed good removal of ciprofloxacin from water. • The hydrogel beads demonstrated feasibility for reuse.