Insight into the antimicrobial and photocatalytic properties of NiO impregnated MCM-48 for effective removal of pathogenic bacteria and toxic levofloxacin residuals

Abstract

NiO impregnated MCM-48 based on recycled silica fume (Ni/SF-MCM-48) was synthesized as a novel nanocomposite of effective photocatalytic and antimicrobial properties. The Ni/SF-MCM-48 is of 2.38 nm pore diameter, 504 m2/g as surface area, and 2.13 eV as bandgap energy which are promising technical properties. The photocatalytic activity of Ni/SF-MCM-48 was evaluated for promising oxidation of Levofloxacin (LVX) residuals and as an antimicrobial agent for Gram-positive bacterium Staphylococcus aureus and Gram-negative bacterium Vibrio sp. The complete oxidation for 10 mg/L, 20 mg/L, 30 mg/L, 40 mg/L, 50 mg/L, and 60 mg/L of LVX was recognized after 20 min, 40 min, 60 min, 70 min, 90 min, and 120 min, respectively using 0.1 g of it as dosage. The oxidation pathway was described based on the obtained intermediate compounds which verified complete converting of them into their end products. Additionally, the trapping tests confirmed an essential role for both the electron-hole pairs and the hydroxyl radicals as the reacting oxidizing species. The recyclability of Ni/SF-MCM-48 showed stability for it for five oxidation experiments achieving a percentage higher than 90% for the inspected tests. The synthetic Ni/SF-MCM-48 composite as antimicrobial agent showed inhabitation zones of 36 mm and 33 mm for Gram-positive Staphylococcus aureus and Gram-negative bacterium Vibrio Sp, respectively. Also, it displayed 18.75 μg/mL and 18.75 μg/mL as minimum inhibitory and minimum inhibitory concentrations against Staphylococcus aureus, respectively.