Adsorption of ciprofloxacin in water using Fe3O4 nanoparticles formed at low temperature and high reactant concentrations in a rotating packed bed with co-precipitation

A rotating packed bed was used to form Fe3O4 nanoparticles at 25 degrees C with a rotational speed of 1800 rpm, flow rates of 0.5 L/min, and FeCl2, FeCl3 , and NaOH concentrations of 0.15 mol/L, 0.3 mol/L, and 1.2 mol/L, respectively. The as-formed Fe3O4 nanoparticles had an average diameter of 9 mn, a BET specific surface area of 140 m(2)/g, and a saturation magnetization of 68 emu/g. The effectiveness of the as-formed Fe3O4 nanoparticles in adsorbing ciprofloxacin in water was evaluated. Increasing the Fe3O4 dosage from 1 to 2.5 g/L reduced the equilibrium adsorption capacity of the as-formed Fe3O4 nanoparticles but increased the efficiency of removal of ciprofloxacin. The equilibrium adsorption capacity of the as-formed Fe3O4 nanoparticles increased with the initial concentration of ciprofloxacin at all pH values. The equilibrium adsorption capacity of the as-formed Fe3O4 nanoparticles was highest at pH 7 with low initial concentrations of ciprofloxacin (10-30 mg/L). However, with high initial concentrations of ciprofloxacin (40-100 mg/L), the equilibrium adsorption capacity of the as-formed Fe3O4 nanoparticles was highest at pH 8. The adsorption of ciprofloxacin onto the as-formed Fe3O4 nanoparticles was more consistent with the Freundlich model than with the Langmuir model at all pH values. At pH 8, an initial concentration of ciprofloxacin of 100 mg/L, and an Fe3O4 dosage of 2.5 g/L, the equilibrium adsorption capacity of the as-formed Fe3O4 nanoparticles was around 24 mg/g. The results demonstrate that the as-formed Fe3O4 nanoparticles are an efficient adsorbent of ciprofloxacin from water.