Background and purpose: Magnetite hydroxyapatite (m-Hap) as a magnetic nano-adsorbent was synthesized for the removal of tetracycline (TC) from aqueous solutions.

Materials and methods: The properties of m-Hap were investigated by scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FTIR). Factors affecting the adsorption of TC including pH (3-10), adsorbent dosage (0.1-5 g/L), contact time (5-120 min) and initial concentration of TC (10-25 mg/L) were investigated. The effect of adsorbent on the removal of tetracycline from real wastewater was also studied.

Results: The nanocomposite was almost spherical in shape and about 20-30 nm in diameter. In optimum conditions more than 99% of TC was removed (contact time 60 min, adsorbent dose 1g/L, and pH 7.5). The equilibrium data were well fitted into Langmuir model (R²= 0.977) and the maximum adsorption capacity was 64.4 mg g^-1 at pH 7.5 and 298 K. Adsorption experiments on hospital wastewater indicated a slight decrease in adsorption removal of TC (85%).

Conclusion: This study showed that the magnetic Hydroxyapatite nanoparticles could be used as a highly efficient and promising adsorbent in water and wastewater treatment systems.