Photocatalytic efficiency of CuNiFe2O4 nanoparticles loaded on multi-walled carbon nanotubes as a novel photocatalyst for ampicillin degradation

Abstract Nickel-copper ferrite nanoparticles (CuNiFe2O4) were loaded onto multi-walled carbon nanotubes (MWCNTs) and used as a novel photocatalyst in the photodegradation of ampicillin (AMP) from aqueous solutions. Photocatalyst properties were characterized by scanning electron microscopy, transition electron microscopy, Fourier-transform infrared spectroscopy, Brunauer–Emmett–Teller analysis, and X-ray diffraction. The results showed that the MWCNTs-CuNiFe2O4 in the UV–photocatalytic process has high degradation efficiency for AMP molecules (100%), compared to adsorption (59.68%), and photolysis (38.41%) processes. At conditions: pH = 5, MWCNTs-CuNiFe2O4 dose = 0.5 g/L, reaction time = 60 min, and UV light intensity = 36 W, the suggested treatment provided a complete degradation rate of AMP, as well as 92.42% TOC removal and 93.32% COD removal. Formation of byproducts including ammonia (NH3), nitrate (NO3–) and sulfate (SO42-) during AMP photocatalytic degradation confirmed mineralization of organic compounds including nitrogen and sulfur compounds, in addition to CO 2 and H 2 O . Scavenging experiments showed that superoxide (•O2–), hydroxyl radicals (•OH) and holes (h+) were produced in the photocatalysis process, however •OH and h+ were the main reactive species. The stability test demonstrated that the photocatalyst could be recycled 8 times with minimal performance reduction for AMP degradation. The energy consumption of the present process for different AMP concentrations was in the range of 5–33.33 kWh/m3, which indicates that the suggested treatment is energy-efficient. Toxicity assessment with E. coli and P. phosphoreum inhibition rates showed that MWCNts-CuNiFe2O4 under UV light has a significant effect on reducing the toxicity ratio of photolysis alone. According to the findings, the application of MWCNTs-CuNiFe2O4 in the UV–photocatalytic process of AMP degradation is an eco-friendly and has high application potential in AMP removal and mineralization.