| The widespread use of heavy metal in industry leads to heavy metal analysis as an important branch of industrial analysis.In recent years,the urgent need for trace heavy metal and speciation analysis has promoted the rapid development of pre-enrichment materials.Graphene nanocomposite has the advantages of large specific surface area,large conjugation system,high strength,strong chemical stability,good electrical conductivity and have the feature of acid,alkali and heat resistance,which been widely used in separation and enrichment of heavy metals.In order to shorten the time consumed by the solid-liquid separation step,Fe3O4 nanoparticles are often used to functionally modify graphene nanocomposite.In this paper,magnetic graphene nanocomposite was synthesized by Fe3O4-SiO2 and graphene.A method using magnetic solid phase extraction(MSPE)coupled with inductively coupled plasma atomic emission spectrometry(ICP-OES)for determination of metal in environmental water samples was developed.The major contents are summarized as follows:(1)Graphene grafted silica-coated Fe3O4 nanoparticles as magnetic solid phase extraction material coupled with ICP-OES for the simultaneous analysis of Mn(?),Cr(?),Pb(?)in water samples.A method using graphene grafted silica-coated Fe3O4 nanoparticles(Fe3O4-SiO2-G)as magnetic solid adsorbent coupled with ICP-OES for determination of Mn(II),Cr(III),Pb(II)in environmental water samples was developed.It was found that Mn(?),Cr(?),Pb(?)can be determined with a very good adsorption efficiency(96.8,100.0,100.0%)on Fe3O4-SiO2-G.The limit detection for 3 metal ions were in the range of 0.076-0.922 ng ·L-1 and the liner range equal to 5.0-90.0?g ·L-1 for Mn(II),4.0-90.0 ?g ·L-1 for Cr(?)and 5.00-90.00 ?g ·L-1 for Pb(II).The enrichment factor of Mn(?),Cr(?),Pb(?)was 80,21,35,respectively.The developed method was successfully applied to the determination of Mn(?),Cr(?),Pb(?)in environmental water samples.(2)Nanoparticles of type Fe3O4-SiO2-graphene oxide and coated with an amino acid-derived ionic liquid for extraction of Al(?),Cr(?),Cu(?),Pb(?)prior to their determination by ICP-OES1-buty1-3-methylimidazole alanine,Fe3O4 nanoparticles and graphene oxide were used to prepare a material for the magnetic solid phase extraction of the ions Al(?),Cr(?),Cu(?)and Pb(?).The material was characterized by Fourier transform infrared spectral,scanning electron microscopy,thermal gravimetric analysis,magnetic analysis and isoelectric point analysis.It is shown to be a viable sorbent for the separation of these metal ions.Under the optimum conditions,the developed method provides a linear range of 10.0-170.0 ?g ·L-1 for Al(?),4.0-200.0 ?g ·L-1 for Cr(?),5.0-170.0?g ·L-1 for Cu(?)and 5.0-200.0 ?g ·L-1 for Pb(?).The limits of detection were 6.20 ng ·L-1 for Al(?),1.60 ng ·L-1 for Cr(?),0.52 ng·L-1for Cu(?)and 30.00 ng ·L-1 for Pb(?).Method performance was investigated by determination of mentioned metal ions in(spiked)environmental water and gave satisfactory recoveries in the range of 89.1-117.8%.(3)Speciation analysis of Cr(?/?)using Fe3O4-SiO2-G coated with an amino acid-derived ionic liquid magnetic solid phase extraction coupled with ICP-OESMagnetic graphene oxide coated with 1-buty1-3-methylimidazole alanine has been developed as a kind of pretreatment method for speciation analysis of Cr(?)and Cr(?)in water samples.The results showed that the concentration of total Cr was quantified by ICP-OES directly,Cr(?)was quantitatively adsorbed after adjusting aqueous sample solution to pH 9.0.And,Cr(VI)was calculated by subtraction of Cr(?)from total Cr.The developed method was investigated by speciation analysis of Cr(?)and Cr(?)in(spiked)environmental water and gave satisfactory recoveries in the range of 88.3-106.2%for Cr(?)and 82.9-111.8%for Cr(?). |
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