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Background and purpose: In recent years, the presence of antibiotics in aquatic environment has received increasing attention. These compounds remain in the environment, because of incomplete elimination in conventional wastewater treatment processes. Advanced oxidation processes are used to remove many pollutants. The aim of this study was to evaluate the efficiency of sono-fenton degradation in removal of sulfacetamide in presence of zerovalent iron nanoparticles.
Materials and methods: An experimental-laboratory scale study was carried out in which NZVI was synthesized through reducing iron sulfate by sodium borohydride. The effects of some variables such as pH (3-9), NZVI concentration (1-8g/L), H₂O₂ concentration (0.05-2 M) and contact time (5-90 min) were investigated on the process efficiency. Concentration of residual antibiotic was analyzed by HPLC-UV equipped with a C18 column.
Results: The maximum removal efficiency was observed at pH=3, 60 min contact time, 5 g/L NZVI concentration and H₂O₂ concentration of 1 M. In these optimal conditions, the removal efficiency was 91% and COD removal degree was 27%.
Conclusion: The experiments showed that the sonocatalytic process using NZVI nanoparticles along with adding H₂O₂ as an oxidant is an efficient method to remove sulfacetamide and other biological resistant compounds.
 

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Background and purpose: Sonocatalytic process as an advanced oxidation process is considered for degradation of pollutants in aqueous solution. The aim of this study was to increase the removal of dye by doping of TiO₂ with non-metal element such as nitrogen.
Materials and methods: Un-doped and N-doped TiO₂ nano-particles with different nitrogen contents were synthesized by a simple sol–gel method in laboratory. X-ray diffraction (XRD), Field emission scanning electron microscopy (FE-SEM), Energy dispersive X-ray analysis (EDX), and UV–visible diffuse reflectance spectra (UV-vis DRS) were used for characterization of the synthesized nanoparticles. The sonocatalytic activity of synthesized nanoparticles was evaluated by investigating degradation of reactive blue 29 under ultrasonic radiation and the effects of nitrogen doping content, different initial pH of solution, and dye concentration.
Results: The study showed that both un-doped and doped nano-particles were in nano-sized that tend to agglomerate. By using different nano-particles, the highest sonocatalytic activity was achieved by 0.6 N-doped TiO₂ with 58 % after 90 min of ultrasonic irradiation. Effect of initial pH of aqueous solution showed that the sonocatalytic activity decreased by increase in initial pH.
Conclusion: Sonocatalysis using N-doped TiO₂ was found to be an effective method for degradation of textile dyes. The high sonocatalytic activity could be attributed to the band gap narrowing and anatase phase in TiO₂ nanoparticles. Sonocatalytic degradation followed the Langmuir–Hinshelwood kinetic model (R² = 0.98) with a rate constant of 0.01 mg L⁻¹ min⁻¹.