Highly efficient degradation of metronidazole drug using CaFe2O4/PNA nanohybrids as metal-organic catalysts under microwave irradiation

Catalytic degradation based on microwave irradiation is an emerging technique which promises prompt and efficient catalytic degradation of organic pollutants. Calcium ferrite (CaFe2O4), poly(1-napththylamine) (PNA), and PNA/CaFe(2)O(4)nanohybrids were synthesized via microwave-assisted technique. The properties of the as-prepared CaFe2O4, PNA, and PNA/CaFe(2)O(4)nanohybrids were characterized by the thermogravimetric analysis (TGA), FTIR, XRD, SEM, and ultraviolet-visible spectrophotometry (UV-vis) analyses. The formation of inorganic-organic hybrids was confirmed by the FTIR and XRD studies. Loading of PNA was confirmed to be 8%, 16%, 32%, and 40% in CaFe(2)O(4)which was established by TGA studies and the thermal stability was found to follow the order: CaFe2O4> 8-PNA/CaFe2O4> 16-PNA/CaFe2O4> 32-PNA/CaFe2O4> 40-PNA/CaFe2O4> PNA. CaFe(2)O(4)and PNA revealed band gap values of 3.42 eV and 2.60 eV respectively while for the PNA/CaFe(2)O(4)nanohybrids, the values were found to be ranging between 2.46 and 3.00 eV. The PNA modified CaFe(2)O(4)nanohybrids showed higher degradation efficiency towards metronidazole (MTZ) drug as compared with PNA and pure CaFe2O4. MTZ drug showed around 94% degradation within 21 min of microwave irradiation using 40-PNA/CaFe(2)O(4)as catalyst. The enhanced catalytic activity was attributed to the high surface area of the nanohybrid catalyst as well as improved microwave catalytic activity of PNA. The reactive species responsible for degradation were confirmed by scavenger studies which formation of(center dot)OH and O(2)(center dot-)radicals. Recyclability tests showed that the 40-PNA/CaFe(2)O(4)nanohybrid exhibited 86% degradation of MTZ (90 mg/l) even after the third cycle, which reflected higher reusability of the catalyst. The MTZ fragments were identified using liquid chromatography-mass spectrometry (LC-MS).

Automated summary

Catalytic degradation based on microwave irradiation shows efficient degradation of organic pollutants. PNA/CaFe(2)O(4) nanohybrids exhibit higher degradation efficiency compared to PNA and pure CaFe2O4, with reactive species responsible for degradation confirmed by scavenger studies. Recyclability tests demonstrate the high reusability of the catalyst even after three cycles.