Preparation Of CoFe₂O₄ Magnetic Composite Materials And Magnetic Solid Phase Extraction Of Organic Pollutants In Water

It is usually difficult to detect organic pollutants directly in water using modem analytical instruments.This is because the concentration of organic pollutants in water is low,impurities are large and the matrix is complex.Therefore,it is significant to develop the new sample pretreatment technologies for the analysis of organic pollutants in water.Magnetic solid phase extraction technology has become an important method for organic pollutant pretreatment due to its advantages of simple operation,low cost,high extraction efficiency and environmental friendliness.In this paper,pyrethroid pesticides,flame retardants and phenoxycarboxylic acid pesticides were selected as target analytes in the water.The cobalt ferrite(CoFe2O4)composites were used for magnetic solid phase extraction of these pollutants,which were then detected by high performance liquid chromatography(HPLC).The structure of these materials were characterized by electron microscopy(SEM5 TEM),X-ray diffraction(XRD),fourier transform infrared spectroscopy(FT-IR),X-ray photoelectron spectroscopy(XPS),thermogravimetric analysis-differential scanning calorimetry(TG-DSC),vibrating sample magnetometer(VSM)and N2 adsorption-desorption analysis.At the same time,the influence of external factors on the effect of magnetic solid phase extraction was investigated.Under the optimal conditions,the method was applied to the detection of environmental water samples.1.CoFe2O4/PGC composite was used for magnetic solid phase extraction of pyrethroid pesticides;(1)Cobalt ferrite embedded porous graphitic carbon(CoFe2O4/PGC)nanocomposite was prepared by a solid state reaction method using glucose as carbon source and sodium chloride as template.The structure of the material was characterized.(2)The pyrethroid pesticides including fenpropathrin(FPT),lambda-cyhalothrin(L-CHT),S-fenvalerate(S-FVL)and bifenthrin(BFT)were selected as the research objects.The effects of material composition,material dosage,system pH,eluent,adsorption time,enrichment factor and material reusability on the treatment effect were studied.(3)In the environmental water sample test,the recoveries and the relative standard deviations of analytes are 80.23-110.93%and 0.19-5.82%,respectively.2.The magnetic solid phase extraction of flame retardants was carried out by CoFe2O4/MIL-101T composite,(1)Cobalt ferrite coated metal organic framework(CoFe2O4/MIL-101T)composite was prepared through the hydrothermal method.The structure of the material was characterized.(2)The flame retardants including triphenyl phosphate(TPP),tetrabromobisphenol A(TBBPA),4-bromodiphenyl ether(BDPE),4,4’-dibromodiphenyl ether(DBDPE)and 4,4’-dibromobiphenyl(DBB)were used as the research objects.The effects of material composition,material dosage,system pH,eluent,adsorption time,enrichment factor and material reusability on the treatment effect were explored.(3)In the environmental water sample test,the recoveries and the relative standard deviations of analytes are 81.62-106.99%and 0.11-8.66%,respectively.3.CoFe2O4/PCPS composite was used for magnetic solid phase extraction of phenoxycarboxylic acid pesticides;(1)Cobalt ferrite embedded porous carbon obtained from peanut shell(CoFe2O4/PCPS)composite was prepared through a solid state reaction method.The structure of the material was characterized.(2)4-chlorophenoxyacetic acid(4-PA),2,4-dichlorophenoxyacetic acid(2,4-D)and 2-(2,4-dichlorophenoxy)propionic acid(2,4-DP)were selected as research objects.The effects of material composition,material dosage,system pH,eluent,adsorption time and enrichnent factor on the treatment effect were investigated.(3)In the environmental water sample test,the recoveries and the relative standard deviations of analytes are 75.22-94.66%and 0.08-3.70%,respectively.