Preparation Of Magnetic Nano-materials And Their Application For Organic Contaminants Extraction In Water

The magnetic composites are formable from composites such as carbon nanotubes,grapheme(GO),palygorskite and the like together with rare earth or other magnetic or magnetizable compounds,or magnetic nano-particles to form structural magnetic composites.Therefore,they are not only widely used in the fields of biology and medicine,but also show unique advantages in the purification and treatment of industrial wastewater,environmental water and groundwater.As for sample treatment procedures,superparamagnetic composites represent one of the most exciting prospects in analytical composites since they can be easily isolated from the matrix by using an external magnetic field.The main advantages over traditional solid-phase extraction sorbents rely on large surface areas,high extraction efficiencies,and use of reduced amounts of sample and toxic organic solvents.In this study,two magnetic composites were prepared.Their structure and feature were characterized by scanning electron microscope,transmission electron microscope and infrared spectroscopyl.They were used for the extraction of organophosphate esters and dye orange yellow II in water.(1)Firstly,Fe3O4 magnetic nanoparticles were synthesized by solvothermal method.Then,a thin SiO2 shell was coated on Fe3O4 surface by modified St?ber method.Finally,Fe3O4@SiO2 nanoparticles were adhered to the surface of multi-walled carbon nanotubes(MWCNTs)by self-assembly and magnetic nanocomposites Fe3O4@SiO2 MWCNTs were obtained.Organophosphate esters(Tributyl phosphate(Tn BP),Tris(2-chloroethyl)phosphate(TCEP),triphenyl phosphate(TPh P),Tris(2-ethylhexyl)phosphate(TEHP))in environmental water were extracted and analyzed by the Fe3O4@SiO2 MWCNTs based on magnetic solid phase extraction coupled with gas chromatography-mass spectrometry(MSPE-GC/MS).Due to the existence of a br?nsted acid–base interaction,van der Waals forces,and a ?–? electron donor–acceptor(EDA)interaction between the OPEs and MWCNTs,OPEs could be selectively extracted by the Fe3O4@SiO2 MWCNT adsorbents.The factors affecting the extraction efficiency of Fe3O4@SiO2 MWCNTs on OPEs were optimized,such as the quality of the adsorbent,the osmotic extraction and elution time,the type and volume of the eluent.The optimized extraction conditions were obtained.Then the linear relationship,quantitative limit,detection limit,the recovery of the method were evaluated.The MSPE-GC/MS method was simple and has good sensitivity and accuracy.Moreover,the preparation of Fe3O4@SiO2 MWCNTs has low cost.The developed MSPE-GC/MS method has better application prospect for extraction of organophosphate esters in water.(2)The Fe3O4@SiO2@CPB magnetic material was prepared and applied to the adsorption of dye orange II in wastewater.The initial concentration of orange II,the adsorption time,and the p H of the solution were studied.The experimental results showed that the adsorption amount increases with the increase of initial concentration and temperature.When the p H is 4,the adsorption amount reaches the maximum.Adsorption kinetics indicated that the adsorption process of orange II by Fe3O4@SiO2@CPB was more consistent with the pseudo second-order reaction model.The isothermal adsorption linear fit shows that the orange ? conforms to Langmuir isothermal adsorption on the magnetic adsorption material.