Biogenic metal nanoparticles with microbes and their applications in water treatment: a review

Due to their unique characteristics, nanomaterials are widely used in many applications including water treatment. They are usually synthesized via physiochemical methods mostly involving toxic chemicals and extreme conditions. Recently, the biogenic metal nanoparticles (Bio-Me-NPs) with microbes have triggered extensive exploration. Besides their environmental-friendly raw materials and ambient biosynthesis conditions, Bio-Me-NPs also exhibit the unique surface properties and crystalline structures, which could eliminate various contaminants from water. Recent findings in the synthesis, morphology, composition, and structure of Bio-Me-NPs have been reviewed here, with an emphasis on the metal elements of Fe, Mn, Pd, Au, and Ag and their composites which are synthesized by bacteria, fungi, and algae. Furthermore, the mechanisms of eliminating organic and inorganic contaminants with Bio-Me-NPs are elucidated in detail, including adsorption, oxidation, reduction, and catalysis. The scale-up applicability of Bio-Me-NPs is also discussed. Graphical abstract