Synthesis Of Magnetic Graphene Oxide And Its Application In The Analysis Of Phenols Residues In Environment Water And Its Adsorption Performance

Pollutants are commonly present in environment at a very low concentration with complex sample matrices.Therefore,to eliminate the matrix interference always requires pretreatment method,such as separation,purification and preconcentration,to improve the detection sensitivity of target analyte.Liquid-liquid extraction and solid phase extraction are the most commonly used sample preparation techniques.However,LLE suffers from the disadvantages of being requiring large amount of toxic organic solvents and time-consuming.SPE techniques typically require a less amount of organic solvents relative to LLE,but SPE can still be time-consuming,and relatively expensive.Recently,a new procedure based on SPE called magnetic solid-phase extraction?MSPE?has been developed.MSPE can avoid traditional solid-phase extraction packing and sampling on column,adsorbent dosage big shortcomings.Magnetic nanomaterial has good magnetic responsiveness,small particle size and big specific surface area,make its can be used for separation and enrichment of phenols pollutant in the environment.This paper is aimed at the preparation of new type of magnetic nanomaterial and development magnetic solid phase extraction?MSPE?technology.The Fe@Fe₂O₃/GO magnetic composite nanoparticle was prepared through the electrostatic interaction between core-shell magnetic Fe@Fe₂O₃ nanostructures and GO nanosheets.The Fe@Fe₂O₃/GO magnetic composite nanoparticle was applied to analysis of phenols residues in environment water and study adsorption performance.The main research content is as follows:1.Graphene oxide?GO?was synthesized using improved Hummer's method.The Fe@Fe₂O₃ nanostructures were synthesized according to the literature method.The Fe@Fe₂O₃/GO magnetic composite nanoparticle was prepared through the electrostatic interaction between Fe@Fe₂O₃ nanostructures and GO nanosheets.The structure,magnetic and microstructure of the Fe@Fe₂O₃,GO and Fe@Fe₂O₃/GO magnetic nanoparticle was examined by scanning electron microscope?SEM?,Fourier infrared spectroscopy?FTIR?,transmission electron microscope?TEM?,vibrating sample magnetometer?VSM?,X-ray powder diffraction?XRD?,Zeta potentiometer,Nitrogen adsorption-desorption.2.Using Fe@Fe₂O₃/GO as magnetic adsorbent,magnetic solid phase extraction three endocrine-disrupting phenols in environmental water samples by coupling with high performance liquid chromatography?HPLC?.The type and amount of adsorbent,pH of water sample,extraction time,type and volume of desorption solution,stable of the material were optimized.Results show that the linear ranges of three phenols were 0.5-100 ng/mL,show a good linear relationship.The limits of detection?S/N=3?ranging from 0.08 to 0.10 ng/mL.The intra-and inter-day precisions with relative standard deviations?RSDs?lower than 7.5%.No residues of phenols were detected in either South lake water or waste water samples and 1.32 ng/mL of BPA and 0.64 ng/mL of DCP were found in plant water sample.The water samples were spiked with the phenols standards at the concentration levels of 5,10,50 ng/mL,respectively.The recovery is between 82%-94.8%.MSPE method can be applied to analysis of three kinds of phenols residues in environmental water samples.3.Use BPA,DCP as the representative of the phenols,we research the adsorption performance of Fe@Fe₂O₃/GO.Various parameters that could affect the adsorption efficiencies,such as adsorption time,temperature,pH and ionic strength were investigated.Results show that adsorption equilibrium time is 1 h.The kinetics data can be well described by the pseudo-second-order kinetic model.Under the study,alkaline,salt conditions are not facilitation the adsorption.Fe@Fe₂O₃/GO to BPA,DCP adsorption is an exothermic process and spontaneous,adsorption capacity decreases with the increase of temperature.The adsorption thermodynamics data can be well described by the Langmuir adsorption model,which is uniform monolayer adsorption.The maximum adsorption capacity of Fe@Fe₂O₃/GO for BPA,DCP obtained from Langmuir adsorption model were 88.5 mg/g,125 mg/g at 298.15K.The adsorption capacity is higher than other carbonaceous adsorbents for BPA,DCP according to the literature.