Optimization of ciprofloxacin and metronidazole removal from wastewater using modified zeolite-iron oxide nanocomposites

The increasing presence of pharmaceutical antibiotics in water systems necessitates research into sustainable, cost-effective water treatment alternatives. This study developed a zeolite – iron oxide nanocomposite, modified with cetyltrimethylammonium bromide surfactant ( CTAB ) using the coprecipitation method. The nanocomposite was characterized using X-ray fluorescence, X-ray diffraction, Fourier-transform infrared spectroscopy, Scanning Electron Microscopy, Zeta Sizer and Brunauer-Emmett-Teller analyses. The nanocomposite was employed in removal of two common pharmaceutical contaminants from water, namely, Ciprofloxacin ( Cipro ) and Metronidazole ( Metro ). Central Composite Design of Response Surface Methodology, was used to assess the influence of pH (3-11), contact time (10-90 min), initial pharmaceutical concentration (0.2-1 mg/L) and adsorbent dosage (0.1-0.5 g) on removal efficiency of the pharmaceuticals. The developed nanocomposite was porous with particle size of 51- 69 nm and surface area 129.41 m 2 /g. The optimal pH (5), contact time (70 min), initial pharmaceutical concentration (0.4 mg/L) and adsorbent dosage (0.4 g) resulted in Cipro and Metro removal of 99.12% and 99.03% respectively. The adsorption process followed Langmuir isotherm model and pseudo-second-order kinetics, with R 2 =0.99 for both models, thus demonstrating a strong fit. Tests with pharmaceutical plant effluent revealed that over 90% contaminants, including selected pharmaceuticals and organic matter, were removed under optimal conditions. Effective pharmaceutical adsorption occurs after the removal of organic matter, as this reduces the competition for active sites. These results demonstrate the potential of nanocomposite to remove pharmaceuticals and other organic constituents from wastewater.