Induced transformation of antimony trioxide by Mn(II) oxidation and their co-transformed mechanism

Antimony(Sb)is a toxic and carcinogenic element that often enters soil in the form of antimony trioxide(Sb_(2)O_(3))and coexists with manganese(Mn)in weakly alkaline conditions.Mn oxides such as birnessite have been found to promote the oxidative dissolution of Sb_(2)O_(3),but few researches concerned the co-transformations of Sb_(2)O_(3) and Mn(II)in environment.This study investigated themutual effect of abiotic oxidation of Mn(II)and the coupled oxidative dissolution of Sb_(2)O_(3).The influencing factors,such as Mn(II)concentrations,pH and oxygen were also discussed.Furthermore,their co-transformed mechanism was also explored based on the analysis of Mn(II)oxidation products with or without Sb_(2)O_(3) using XRD,SEM and XPS.The results showed that the oxidative dissolution of Sb_(2)O_(3) was enhanced under higher pH and higher Mn(II)loadings.With a lower Mn(II)concentration such as 0.01 mmol/L Mn(II)at pH 9.0,the improved dissolution of Sb_(2)O_(3) was attributed to the generation of dissolved intermediate Mn(III)species with strong oxidation capacity.However,under higher Mn(II)concentrations,both amorphous Mn(III)oxides and intermediate Mn(III)species were responsible for promoting the oxidative dissolution of Sb_(2)O_(3).Most released Sb(∼72%)was immobilized by Mn oxides and Sb(V)was dominant in the adsorbed and dissolved total Sb.Meanwhile,the presence of Sb_(2)O_(3) not only inhibited the removal of Mn(II)by reducing Mn(III)to Mn(II)but also affected the final products of Mn oxides.For example,amorphous Mn oxides were formed instead of crystalline Mn(III)oxides,such as MnOOH.Furthermore,rhodochrosite(MnCO_(3))was formed with the high Mn(II)/Sb_(2)O_(3) ratio,but without being observed in the low Mn(II)/Sb_(2)O_(3) ratio.The results of study could help provide more understanding about the fate of Sb in the environment and the redox transformation of Mn.

Synthesis and Purple-Blue Emission of Antimony Trioxide Single-Crystalline Nanobelts with Elliptical Cross Section

Single-crystalline orthorhombic antimony trioxide(Sb_(2)O_(3))nanobelts with unique elliptical cross sections and purple-blue photoluminescence have been synthesized.The uniform Sb2O3 nanobelts are 400600 nm in width,2040 nm in thickness at the center and gradually become thinner to form sharp edges sub-5 nm in size,tens of micrometers in length,and with[001]as the preferential growth direction.Self-assembly of tens of nanobelts into three-dimensional(3-D)flower-like nanostructures has been observed.Analysis was performed by X-ray diffraction,energy-dispersive X-ray spectroscopy,X-ray photoelectron spectroscopy,scanning electron microscopy,high-resolution transmission electron microscopy,selected area electron diffraction,Raman spectroscopy,Fourier transform infrared spectroscopy,and photoluminescence spectroscopy.The Sb_(2)O_(3) nanobelts display intense purple-blue photoluminescence centred at 425 nm(~2.92 eV).The successful synthesis of nanobelts with elliptical cross sections may cast new light on the investigation of the property differences between nanobelts with rectangular cross sections and those with other cross section geometries.The Sb2O3 nanobelts can be used as effective purple-blue light emitters and may also be valuable for future nanodevice design.