Facile and eco‐benign synthesis of a novel MnFe2O4@SiO2@Au magnetic nanocomposite with antibacterial properties and enhanced photocatalytic activity under UV and visible‐light irradiations

The purpose of this research is to prepare novel, inexpensive, eco‐friendly and efficient magnetic nanocomposites for degradation of pollutant from wastewater and their potential antibacterial activity. To reach this goal, we have synthesized magnetic MnFe2O4@SiO2@Au (MnFe@Si@Au) nanocomposites through ultrasound assisted co‐precipitation technique in presence of carbohydrate and Crataegus fruits extract, for the first time. The influence of capping agents including sucrose, glucose, PVA and reducing agents such as C. microphylla and C. pentagyna on the morphology, size, purity, photocatalytic and antibacterial behavior of magnetic nanocomposites were investigated. The FT‐IR, XRD, VSM, EDS, FE‐SEM, TEM and BET analysis were performed to confirm the formation of magnetic nanocomposites. MnFe@Si@Au nanocomposites have shown promising potential in degradation of organic contaminants including rhodamine b (RhB), 2‐naphthol (2‐NPH), methyl violet (MV), erythrosine (ER) and eriochrome black T (EBT) under both radiation conditions. The results show that degradation of the anionic contaminants is more than cationic contaminants under UV and visible irradiations. As well as, these synthesized spherical MnFe@Si@Au nanocomposites show excellent antibacterial activities against P. aeruginosa, K. pneumoniae and P. mirabilis bacteria. In addition to the features mentioned, another prominent feature of this nanocatalyst is retaining their photocatalytic activity after five cycles of utilization. 1. Green synthesis of MnFe@Si@Au nanocomposites in presenceof crataegus fruits extract. 2. Enhanced performance of MnFe@Si@Au nanocomposites for degradation of cationic and anionic contaminants. 3. High antibacterial activities of the biosynthesized MnFe@Si@Au nanocomposites againstgram‐negative and gram‐positive strains.