Nan Wang,Huijuan Chai,Xuelin Dong,Qian Zhou,Lihua Zhu
Iron(III) ethylenediaminetetraacetate (Fe(III)EDTA) is widely used in iron fortification for reducing iron deficiency, and its determination is urgently needed. The present work developed a fluorescent method to straightforwardly determine Fe(III)EDTA by using photoluminescent carbon dots (C-dots) with the aid of F − ions as the masking agent of free Fe 3+ ions. In the presence of F − ions, only Fe(III)EDTA selectively quenched the photoluminescence of C-dots, and both Fe 3+ and Fe 2+ as well as other carboxylic acids have no effect on the emission of C-dots. The sensing mechanism was attributed to the ligand-tailored electron transfer process from C-dots to Fe 3+ . Under optimum conditions, this method showed a linear calibration plot over the Fe(III)EDTA range of 1.0–200 μmol L −1 and a detection limit of 0.4 μmol L −1 . The proposed method was successfully applied to determine Fe(III)EDTA in real samples with acceptable recoveries of spikes (95%−110%) and repeatability (RSD, 4.2%−9.5%).
Magnetic poly(styrene–glycidyl methacrylate) porous microspheres (MPPM) with high magnetic contents were prepared by surfactant reverse micelles and emulsion polymerization of monomers, in which the well-dispersed Fe 3 O 4 nanoparticles were modified by polyethylene glycol (PEG) and oleic acid (OA) respectively. The characterizations showed that both of the OA–MPPM and the PEG–MPPM were ferromagnetic, however, the OA–MPPM was used to immobilize the bacteria for more advantages. Therefore, the effects of monomer ratio, surfactant, crosslinker and amount of Fe 3 O 4 on the structure, morphology and magnetic contents of the OA–MPPM were investigated. Then, the OA–MPPM was utilized to immobilize Klebsiella sp. FD-3, an iron-reducing bacterium for Fe(III)EDTA reduction applied in NO x removal. Compared with free bacteria, the immobilized FD-3 showed a better tolerance to the unbeneficial pH and temperature conditions.
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