Water-soluble Prussian-blue (PB) analogue transition metal hexacyanoferrate (HCF) nanoparticles FeHCF, CoHCF, NiHCF and CuHCF have been synthesized by using poly(N-vinyl-2-pyrrolidone) as a protective matrix. Transmission electron microscopy (TEM) images of the synthesized PB analogues showed stable and well dispersed nanoparticles with fairly narrow size distributions. Depending on transition metal ions, the PB analogue nanoparticles exhibited various novel shapes but with similar average sizes within the range of 45-60 nm. Spherical NiHCF, cubic CoHCF and CuHCF, and frustum-of-pyramid-like FeHCF nanoparticles, have been characterized from the TEM images. X-ray diffraction (XRD) analysis further identified a face-centred cubic structure of the nanoparticles. The FTIR and UV-vis spectroscopy were employed to investigate the optical properties of the nanoparticle-PVP composites, showing distinguished optical and electronic transitions from conventionally synthesized nanoparticles. The effect of feed ratio of PVP to transition metal ions on the size and optical properties of the nanoparticles was also discussed.
A rapid, simple, and reliable method of solid-phase extraction (SPE) combined with gas chromatography (GC)-mass spectrometry (MS) is developed for the analysis of a wide range of polarity of unknown organic pollutants in sewage. Wastewater samples are extracted by passing them through disposable C(18) cartridges, and the extracts are then analyzed by GC-MS. Different SPE parameters for ten organic compounds in the list of priority pollutants suggested by the China Environmental Protection Agency (EPA) are studied, and their breakthrough volumes are determined. Extraction recoveries for the tested compounds are greater than 60%, except the recovery of 1,2-dichloroethane is 48%. The relative standard deviations are less than 7.8% (n = 3). The developed approach is successfully applied for the identification of organic components in a sewage sample. Over 220 organic pollutants are identified, with 5 of these present in the list of priority pollutants suggested by the U.S. EPA and 4 from the list by the China EPA.
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