Combined Effect of Adsorption and Photocatalytic Degradation Using Magnesium Oxide Nano-flowers for Tetracycline Removal

The extensive use of antibiotics, including tetracycline (TC), has several negative impacts on ecosystems that need attention. In the present study, magnesium oxide nano-flowers (MgO NFs) were examined as an adsorbent and as a degradation photocatalyst for TC elimination. MgO NFs were characterized by XRD, UV-Vis, PL, SEM, TEM, and FTIR. Optimization of the removal process included varying the treatment time, initial pH, MgO NFs dosage, and testing with different initial TC concentrations. The highest removal efficiency (77.3%) was achieved for 50 mg/L TC using 0.6 g/L of MgO NFs at pH 9. Adsorption removal contributed to 26.0% of this removal, while 51.3% was attributed to photocatalytic removal. A one-way analysis of variance (ANOVA) revealed significant impacts of time, initial pH, MgO NFs dose, and initial TC concentrations on TC removal. Although adding different ions showed strong effects on TC adsorption on MgO NFs, those ions inhibited TC removal by about 5% after photocatalytic degradation. Adsorption data fitted well with the Langmuir isotherm and pseudo-second-order kinetic models, the adsorption process was monolayer on a homogenous surface based on chemical interactions. Based on the Langmuir-Hinshelwood model, t 1/2 values ranged from 60.79 to 76.15 min for TC concentrations varying from 10 to 60 mg/L. Bacterial growth inhibition of Escherichia coli (ATCC 25,922) and Bacillus cereus (ATCC 33,019) were reduced after TC treatment. The study evidenced that using MgO NFs in photodegradation is an effective approach for TC removal from water bodies.