A magnetically recyclable nanocomposite catalyst for olefin epoxidation

Magnetic nanocomposites with mesoporous structures: synthesis and applications

Magnetic nanocomposites with well-defined mesoporous structures, shapes, and tailored properties are of immense scientific and technological interest. This review article is devoted to the progress in the synthesis and applications of magnetic mesoporous materials. The first part briefly reviews various general methods developed for producing magnetic nanoparticles (NPs). The second presents and categorizes the synthesis of magnetic nanocomposites with mesoporous structures. These nanocomposites are broadly categorized into four types: monodisperse magnetic nanocrystals embedded in mesoporous nanospheres, microspheres encapsulating magnetic cores into perpendicularly aligned mesoporous shells, ordered mesoporous materials loaded with magnetic NPs inside the porous channels or cages, and rattle-type magnetic nanocomposites. The third section reviews the potential applications of the magnetic nanocomposites with mesoporous structures in the areas of heath care, catalysis, and environmental separation. The final section offers a summary and future perspectives on the state-of-the art in this area.

Recycling functional colloids and nanoparticles

The stability and separation of colloids and nanoparticles has been addressed in numerous studies. Most of the work reported to date requires high cost, energy intensive approaches such as ultracentrifugation and solvent evaporation to recover the particles. At this point of time, when green science is beginning to make a real impact, it is vital to achieve efficient and effective separation and recovery of colloids to provide environmental and economic benefits. This article explores recent advances in strategies for recycling and reusing functional nanomaterials, which indicate new directions in lean engineering of high-value nanoparticles, such as Au and Pd.

Templated preparation of porous magnetic microspheres and their application in removal of cationic dyes from wastewater

Porous magnetic microspheres with large particle size (350-450 microm) were prepared with sulfonated macroporous polydivinylbenzene as a template. The preparation process included ferrous ion exchange and following oxidation by hydrogen peroxide. The results showed that the weight fraction of magnetic nanoparticles exceeded 20 wt% in microspheres after the preparation process was repeated three times. X-ray diffraction profiles indicated that the crystalline phase of as-formed magnetic nanoparticles was magnetite (Fe(3)O(4)). TEM images revealed rod-like magnetite crystal after the first oxidation cycle, however, the crystal morphologies were transferred into random shape after more oxidation cycles. The applicability of porous magnetic microspheres for removal of cationic dyes from water was also explored. The results exhibited that basic fuchsin and methyl violet could be quickly removed from water with high efficiency. More importantly, the magnetic microspheres could be easily regenerated and repeatedly employed for wastewater treatment. Therefore, a novel methodology was provided for fast removal cationic dyes from wastewater.

Magnetite nanoparticle-supported coordination polymer nanofibers: synthesis and catalytic application in Suzuki-Miyaura coupling

Functional nanoscale coordination polymers are receiving growing scientific interest because of their potential applications in many domains. In this paper, we demonstrated that a nanofibrous networked metal-organic gel (G1-MNPs) was formed by simply mixing 4,4',4''-(1,3,5-triazine-2,4,6-triyl)tris(N-(pyridin-3-ylmethyl)benzamide) (L) and Pd(COD)(NO(3))(2) in CHCl(3)-MeOH with a Pd/L molar ratio of 1:1 in the presence of magnetite nanoparticle (MNPs). The self-assembly behavior of nanofibers was not significantly effected by the introduction of magnetite nanoparticles. The xerogel of G1-MNPs was superparamagnetic and showed catalytic activity in Suzuki-Miyaura C-C coupling reactions. The Pd(II) xerogel could be magnetically isolated and recycled with a permanent magnet. It represents a novel strategy to introduce nanoparticles into functional coordination polymers for multifunctional materials.

Magnetic separable PSA@Fe3O4/Ag composites — Fabrication and catalytic properties

A novel PSA@Fe3O4/Ag composite, with high efficiency in the degradation of Rhodamine B, was synthesized through a simple wet-chemistry method. The results showed that the rate of the catalytic reaction was significantly concentration-dependent. Furthermore, there was no significant loss in the catalytic activity of the recycled catalysts, even after being recycled nine times (average 83%), from which one can deduce that almost all the nanosilver were regathered due to the super-paramagnetic Fe3O4 nanoparticles.

Oxidase-like activity of polymer-coated cerium oxide nanoparticles

Inorganic enzyme? Ceria nanoparticles exhibit unique oxidase-like activity at acidic pH values. These redox catalysts can be used in immunoassays (ELISA) when modified with targeting ligands (see picture; light blue and yellow structures are nanoparticles with attached ligands). This modification allows both for binding and for detection by the catalytic oxidation of sensitive colorimetric dyes (e.g. TMB).