Controllable Synthesis And Mechanism Of Zerovalent Iron Nanoparticles Under Interfacial Interactions Between Delaminated

Montmorillonite is one of the most protective reagents and supports in the zero-valent iron nanoparticles preparation process. Adding water-soluble polymer in reactions with montmorillonite can further improve the monodispersity and practical performance of nanoparticles. In the present paper, we research into the reaction of montmorillonite based zero-valent iron nanoparticles with different water-soluble polymers including PVP, PEI and PAA. Through experiments, we select PVP as the most efficient protection reagent. With exploring the best method for preparation under PVP, we get the production with high monodispersity and stable performance which has more practical value.The main conclusions of this work are made as follows:1. A combination of characterizations reveals that in the presence of PVP, the obtained zero-valent iron nanoparticles supported on the surface out of montmorillonite with roughly spherical morphology have higher monodispersity and dispersion well. In the core-shell structure of this zero-valent iron nanoparticles, the shell has two-layer which was polymer shell on the most out layer and iron oxide shell on secondary outer layer stabilized at 3 nm play preventing aggregating after nanoparticles growing stable and stop oxidating role respectively.2. The dispersion effect of PVP is the result of two aspects. One is that the radicle in PVP helps itself to absorb on the surface of montmorillonite sheet and to intercalate the interlayer, thus lamellar structure electrostatic repulse each other and form the card house structure which is beneficial to disperse nanoparticles. The other is forming protective PVP shell avoids nanoparticles attracting with each other. Both the two phenomena play the role of deducing the size of zero-valent iron nanoparticles.3. In the process of preparation, large molecular weight PVP occurs stronger interaction between molecular chain itself which weakens adsorption on the surface of montmorillonite and nanoparticles. And the dominant interaction between PVP and montmorillonite promotes the formation of card house structure, less low molecular weight polymer chains are more beneficial to bridging and stable it. Furthermore high concentration of reducing agent can increase the number of zero-valent iron crystal nucleus and decrease the particle size as well.