Encapsulation of superparamagnetic Fe_3O_4@SiO_2 core/shell nanoparticles in MnO_2 microflowers with high surface areas

Microflowers made of interconnected MnO2 nanosheets have been successfully synthesized in a microwave reactor through a hydrothermal reduction of KMnO4 with aqueous HCI at elevated temperatures in the presence of superparamagnetic Fe3O4SiO2 core-shell nanoparticles.Due to the chemical compatibility between SiO2 and MnO2,the heterogeneous reaction leads to the spontaneous encapsulation of the Fe3O4@SiO2 core-shell nanoparticles in the MnO2 microflowers.The resulting hybrid particles exhibit multiple properties including high surface area associated with the MnO2nanosheets and superparamagnetism originated from the Fe3O4@SiO2 core-shell nanoparticles.which are beneficial for applications requiring both high surface area and magnetic separation.

Synthesis,Structural and Optical Properties of Mn-Doped Ceria Nanoparticles:A Promising Catalytic Material

The structure,the morphology and the thermal,optical and the surface properties of nanocrystalline CeO_2 doped with Mn have been studied by X-ray diffraction（XRD）,field-emission transmission electron microscopy（FE-TEM）,energy-dispersive X-ray analysis,thermogravimetric analysis,UV–Vis absorption spectroscopy and Fourier transform infrared spectroscopy.The XRD results confirmed the successful incorporation of Mn into the CeO_2 lattice through the formation of nanoscale face-centered cubic solid solution.The FE-TEM observations supported the nanocrystalline nature of the solid solutions.The presence of structural defects and their role on the band gap have been discussed on the basis of absorption spectral studies.The structural differences correlate with results from temperature-programmed reaction（TPR）experiments with H_2 consumption.The TPR measurements showed an enhanced bulk reduction at much lower temperatures,indicating increased oxygen mobility in the samples,which enable to enhanced oxygen diffusion at lower temperatures.

Synthesis of a highly recoverable 3D MnO2/rGO hybrid aerogel for efficient adsorptive separation of pharmaceutical residue

Water contamination by non-steroidal anti-inflammatory drugs,such as acetaminophen,is an emerging ecological concern.In this study,a newthree-dimensionalmanganese dioxideengrafted reduced graphene oxide(3D MnO_(2)/rGO)hybrid aerogel was developed for acetaminophen sequestration.The synthesis involved firstly the self-assembly of GO aerogel,followed by thermal reduction and in-situ MnO_(2) growth by redox-reaction.The aerogel demonstrated interlinked planes with smooth surfaces deposited with MnO_(2) nanospheres and pores of 138.4–235.3μm width.The influences of adsorbent dosage,initial pH,acetaminophen concentration,temperature and contact time were investigated.It was determined that the adsorption of acetaminophen occurred on uniform sorption sites in the aerogel,as suggested by the best fit of data to the Langmuir isotherm,yielding a maximum adsorption capacity of 252.87 mg/g.This highest adsorption performance of the 3D MnO_(2)/rGO aerogel was attained at a dosage of 0.6 g/L,initial pH of 6.2 and temperature of 40℃.The process kinetics were in-line with the pseudo-first-order and pseudo-second-order kinetics at 10 and 20–500 mg/L concentrations,respectively.Thermodynamic assay showed the spontaneity and endothermicity features of the 3D MnO_(2)/rGO-acetaminophen system.The acetaminophen adsorption mechanisms were mainly hydrogen bonding and pore entrapment.Moreover,the as-synthesised aerogel was effectively regenerated using acetone and re-utilised in four adsorption-desorption cycles.Overall,the results highly recommend the implementation of the 3D MnO_(2)/rGO hybrid aerogel for purification of wastewater polluted by acetaminophen residue.