Environmental applications of MnFe 2 O 4 and MnFe 2 O 4 /2D- nanocomposites for heavy metals, pharmaceuticals, dyes and antibacterial activity: a review

Manganese ferrite is gaining strong attention as an advanced material for environmental purification because of its intrinsic and extrinsic properties. As a photocatalyst it offers an effective near visible light band gap and active electron–hole transfer ability which supports the formation of reactive oxygen species for rapid degradation of aquatic pollutants. The material also exhibits excellent room temperature magnetic properties that enable easy recovery and reusability. However, MnFe 2 O 4 shows fast electron–hole recombination rate which limits its photocatalytic efficiency. This issue can be overcome by combining MnFe 2 O 4 with two-dimensional (2D) materials such as graphene, MoS 2 , MXene, g-C 3 N 4 , etc. These composites show significant improvement in catalytic activity, stability, reusability and visible light response. The hybrid structures form heterojunctions prevent faster recombination and the surface morphology provide more active surface sites for pollutant removal. These nanocomposites have demonstrated excellent performance in removing harmful metals including Cr(III), Cr(VI), Pb(II), Cd(II), As(III), As(V), etc as well as antibiotics such as norfloxacin, ciprofloxacin and tetracycline. They are also highly effective in degrading dyes such as methylene blue, methyl orange, rhodamine B and congo red and show strong antibacterial activity against both gram positive and gram negative species. This review highlights recent developments in the structure and synthesis of MnFe 2 O 4 and its 2D-nanocomposites and summarizes their adsorption capacity and photocatalytic efficiency. It also explains their pollution removal mechanisms and evaluates their reusability and practical potential studies. The study further discusses key research challenges including the need for improved stability prevention of metal leaching and scalable production for real wastewater treatment applications.