Synthesis Of Functionalized Magnetic Nanomaterials And Their Applications In Environmental Monitoring

Organic pollutants and heavy metals entering the environment through various ways may cause water pollution,which has become a global environmental problem because of its great harm to human health and environmental safety.Therefore,it is necessary to establish simple,sensitive and rapid and easy to operate determination methods.Magnetic solid phase extraction(MSPE)has advantages of rapid separation,high enrichment efficiency,low consumption of organic solvents and environmental friendliness.However,the unmodified iron oxide(Fe3O4)and nanoscale zero-valent iron are easy to be agglomerated and oxidized,and there are few surface functional groups,which limit their ability to adsorb and enrich pollutants and have a narrow application area.Therefore,surface modification to enhance the dispersibility,stability and selectivity to the targets,and expand the application of magnetic materials has become one of the research hotspots.Based on this,three functionalized magnetic nanomaterials were designed and synthesized,and which were used as the adsorbents of MSPE to establish three new methods for enrichment and detection of typical organic pollutants and heavy metal pollutants in environmental water in combination with high performance liquid chromatography(HPLC)and gas chromatography-tandem mass spectrometry(GCMS/MS).The details were as follows.In the first part,a magnetic nanomaterial,Fe@SiO2@PANI,was designed and synthesized.A new method was developed for simultaneous enrichment and determination of three phenolic pollutants including bisphenol A,tetrabromobisphenol A and 4-nonylphenol with the prepared material as a magnetic adsorbent prior to HPLC equipped with variable wavelength ultraviolet(VWD)and fluorescence detector(FLD).The extraction parameters were also optimized in detail.Under the optimal conditions,the linear ranges of bisphenol A,tetrabromobisphenol A and 4-nonylphenol was 0.05100 ?g/L,0.05-300 ?g/L and 0.05-250 ?g/L,respectively.The LODs were in the range of 0.009-0.073 ?g/L,and the spiked recoveries of actual water samples were in the range of 92.9-98.9%.In the second part,a magnetic poly(amidoamine)dendrimer,MNPs@PAMAM-Gn,was designed and synthesized,which coupled to HPLC was utilized to develop a sensitive method for simultaneous detection of Cd2+and Hg2+from the environmental water samples.Under the optimal conditions,the linear ranges of Cd2+and Hg2+were 0.05-200?g/L and 0.1-200 ?g/L,respectively.The detection limits of Cd2+and Hg2+were 0.016 and 0.04 ?g/L,respectively.The spiked recoveries of real water samples were in the range of 91.5-105.0%.In the third part,the magnetic nanomaterial MNPs@PAMAM-Gn was modified with multi-walled carbon nanotubes(MWCNTs).This material exhibited excellent adsorption capacity to carbazole(CZ),7-methylquinoline(7-MQL),9-methylcarbazole(9MCZ),dibenzothiophene(DBT),4-methyldibenzothiophene(4-MDBT)and 4,6dimethyldibenzothiophene(4,6-DMDBT),and a new method was established to determine these heterocyclic pollutants by gas chromatography-tandem mass spectrometry.Under the optimal conditions,7-MQL,DBT and CZ had a good linearity in the concentration range of 0.005-20 ?g/L,and 9-MCZ,4-MDBT and 4,6-DMDBT had good linearity in the range of 0.001-20 ?g/L.The limits of detection were in the range of 2.2'10-4-1.8'10-3 ?g/L.The precisions were all below 8.28%.The spiked recoveries of environmental water samples were between 87.0%and 115.1%.