Preparation of a Fe3O4-Au-GO nanocomposite for simultaneous treatment of oil/water separation and dye decomposition

In situ decoration of Au NPs over polydopamine encapsulated GO/Fe3O4 nanoparticles as a recyclable nanocatalyst for the reduction of nitroarenes

A new and efficient catalyst has been designed and prepared via in situ immobilization of Au NPs fabricated polydopamine (PDA)-shelled Fe3O4 nanoparticle anchored over graphene oxide (GO) (GO/Fe3O4@PDA/Au). This novel, architecturally interesting magnetic nanocomposite was fully characterized using different analytical techniques such as Field Emission Scanning Electron Microscopy, Energy Dispersive X-ray Spectroscopy, elemental mapping, Transmission Electron Microscopy, Fourier Transformed Infrared Spectroscopy, X-ray Diffraction and Inductively Coupled Plasma-Atomic Electron Spectroscopy. Catalytic activity of this material was successfully explored in the reduction of nitroarenes to their corresponding substituted anilines, using NaBH4 as reducing agent at ambient conditions. The most significant merits for this protocol were smooth and clean catalysis at room temperature with excellent productivity, sustainable conditions, ease of separation of catalyst from the reaction mixture by using a magnetic bar and most importantly reusability of the catalyst at least 8 times without any pre-activation, minimum loss of activity and considerable leaching.

Magnetic Nanoparticle Composites: Synergistic Effects and Applications

Composite materials are made from two or more constituent materials with distinct physical or chemical properties that, when combined, produce a material with characteristics which are at least to some degree different from its individual components. Nanocomposite materials are composed of different materials of which at least one has nanoscale dimensions. Common types of nanocomposites consist of a combination of two different elements, with a nanoparticle that is linked to, or surrounded by, another organic or inorganic material, for example in a core-shell or heterostructure configuration. A general family of nanoparticle composites concerns the coating of a nanoscale material by a polymer, SiO2 or carbon. Other materials, such as graphene or graphene oxide (GO), are used as supports forming composites when nanoscale materials are deposited onto them. In this Review we focus on magnetic nanocomposites, describing their synthetic methods, physical properties and applications. Several types of nanocomposites are presented, according to their composition, morphology or surface functionalization. Their applications are largely due to the synergistic effects that appear thanks to the co-existence of two different materials and to their interface, resulting in properties often better than those of their single-phase components. Applications discussed concern magnetically separable catalysts, water treatment, diagnostics-sensing and biomedicine.

Multifunctional CNTs-PAA/MIL101(Fe)@Pt Composite Membrane for High-throughput Oily Wastewater Remediation

A surge of effort has been devoted to establishing super-wetting membranes with versatility for oily waste water purification. However, persistent challenge remains the lower separation flux. Moreover, the majorities of catalysts are only adsorbed on the surface and easily fall off after multiple cyclic separations. In this work, an effective strategy has been taken to construct a composite membrane consisting of polyacrylic acid functionalized carbon nanotubes (CNTs-PAA) and MIL101(Fe)@platinum nanoparticles (MIL101(Fe)@Pt NPs). The obtained CNTs-PAA/MIL101(Fe)@Pt composite membrane can achieve degradation of dye molecules and at the same time effective separation of oil-in-water emulsions. The separation throughput of this composite membrane can reach up to 11000 L m^-2 h^-1 bar^-1, which has exceeded most of the previous reported multifunctional separation membranes. Furthermore, this composite membrane has presented stable mechanical property and excellent anti-corrosion ability. This work gives comprehensive consideration to excellent separation performance, versatility and stability, which could have potential applications in practical oily wastewater treatment.

Enhanced Catalytic Reduction of 4-Nitrophenol Driven by Fe₃O₄-Au Magnetic Nanocomposite Interface Engineering: From Facile Preparation to Recyclable Application

In this work, we report the enhanced catalytic reduction of 4-nitrophenol driven by Fe₃O₄-Au magnetic nanocomposite interface engineering. A facile solvothermal method is employed for Fe₃O₄ hollow microspheres and Fe₃O₄-Au magnetic nanocomposite synthesis via a seed deposition process. Complementary structural, chemical composition and valence state studies validate that the as-obtained samples are formed in a pure magnetite phase. A series of characterizations including conventional scanning/transmission electron microscopy (SEM/TEM), Mössbauer spectroscopy, magnetic testing and elemental mapping is conducted to unveil the structural and physical characteristics of the developed Fe₃O₄-Au magnetic nanocomposites. By adjusting the quantity of Au seeds coating on the polyethyleneimine-dithiocarbamates (PEI-DTC)-modified surfaces of Fe₃O₄ hollow microspheres, the correlation between the amount of Au seeds and the catalytic ability of Fe₃O₄-Au magnetic nanocomposites for 4-nitrophenol (4-NP) is investigated systematically. Importantly, bearing remarkable recyclable features, our developed Fe₃O₄-Au magnetic nanocomposites can be readily separated with a magnet. Such Fe₃O₄-Au magnetic nanocomposites shine the light on highly efficient catalysts for 4-NP reduction at the mass production level.