Magnetic Multi‐Functional Nano Composites for Environmental Applications

Abstract

A novel concept is proposed to synthesize a new class of composites featuring magnetic, molecular sieve and metallic nanoparticle properties. These multi‐functional materials have potential applications as recyclable catalysts, disinfectants and sorbents. The magnetic property enables effective separation of the spent composites from complex multiphase systems for regeneration and recycle, safe disposal of the waste and/or recovery of loaded valuable species. The zeolite molecular sieve provides a matrix which supports a remarkably new, simple, efficient and economical method to make stable, supported silver nanoparticles by silver ion exchange and controlled thermal reduction. The silver nanoparticles generated in this way have excellent properties such as high reactivity and good thermal stability without aggregation, which act as nano reactors for desired functionality in a wide range of applications. Magnetic component (Fe3O4), molecular sieve matrix (zeolite) and silver nanoparticles generated by ion exchange followed by controlled reduction, together form this unique novel composite with designed functions. It represents a practically operational, economical, sustainable and environmentally friendly new advanced functional material. This paper focuses on the novel synthesis and characterization of the composite, with an example of applications as sorbents for the removal of vapor‐phase mercury from the flue gas of coal‐fired power plants.

Bio-inspired formation of functional calcite/metal oxide nanoparticle composites

“…Greater control can be achieved using more complex processing such as formation of alternate layers using physical deposition or chemical solution processing. 25 Alternatively, inorganic nanoparticles can be embedded within an inorganic matrix, for example by the in situ growth of nanoparticles within porous media such as zeolites, 26 the construction of mesoporous solids in the presence of nanoparticles, 27 adsorption of nanoparticles into porous crystals, 28 the formation of discrete coreshell nanoparticle composites, 29 and in situ growth of nanoparticles during thin film formation. 30 It is emphasized that in creating these composite materials, there is a requirement not only to succeed in embedding nanoparticles within the host matrix, but to control their density and distribution.…”

Nanosized Cation-Deficient Fe−Ti Spinel: A Novel Magnetic Sorbent for Elemental Mercury Capture from Flue Gas

“…32,33 The separation of sorbent from the fly ash may be more easily achieved by the magnetic property of the sorbent. A magnetic sorbent MagZ-Ag 0 was once used to capture elemental mercury from flue gas, 31,34 but the sorbent was expensive.…”

Nanocomposites of graphene oxide, Ag nanoparticles, and magnetic ferrite nanoparticles for elemental mercury (Hg0) removal

“…Therefore, porous materials [13][14][15][16][17] such as activated carbons, zeolite, and mesoporous silica have been extensively explored as scaffolds to impregnate active chemicals including chlorine, sulfur, bromide, iodine and noble metals, and are employed as adsorbents. 13,18,19 However, most of these sorbents are difficult to regenerate due to the strong chemical interactions involved in mercury adsorption, thereby incurring high operating costs. It is of paramount benet to explore a novel scaffold and develop efficient mercury adsorbents with feasible recycling ability under suitable regeneration temperature, which will not only greatly enhance the mercury removal performance but also signicantly reduce the operation cost of sorbent injection.…”