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 CO2 and H2O. 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.