Preparation And Application Of New Magnetic Solid Phase Extraction Materials

In this paper,two new magnetic solid phase extraction materials were prepared.The prepared adsorbents were characterized by scanning electron microscopy?SEM?and Fourier infrared spectrometer.The above two magnetic solid phase extraction materials were applied to extraction microcystins and congo red dye from solution.?1?Microcystins,produced by freshwater cyanobacteria,are a class of serious water pollutant.It is necessary to monitor their concentration in drinking water.The Fe₃O₄@SiO₂@CPC magnetic composites modified with cetylpyridinium chloride?CPC?was synthesized as follow: firstly,Fe₃O₄ was prepared by hydrothermal synthesis method,and Fe₃O₄@SiO₂ was prepared by coating a layer of SiO₂ on the surface of Fe₃O₄ by hydrolyzing of orthosilicate?TEOS?.Then,cetylpyridinium chloride?CPC?and the second SiO₂ layer were coated on the surface of Fe₃O₄@SiO₂.Subsequently,the received composites were used as solid phase extraction sorbent to extraction microcystins from solution.Due to the presence of CPC,a large amount of positively charged ammonium ions existed on the surface of the adsorbent and the negative charged microcystins were easily absorbed by the adsorbent with positive charges.The optimum extraction of microcystins in water samples was achieved by optimizing the amount of the adsorbent,adsorption time,the type of eution solvent and the volume of eluent.And the linear rrlationship,quantitative limit,detection limit,the standard deviation of the method were evaluated.In this experiment,a method for quantitative analysis of trace microcystins?MC-LR and MC-RR?in environmental water samples has been developed,which has the advantages of low detection limit,low consumption of organic solvent and low finished product.?2?Magnetic multi-walled carbon nanotubes was parepared by combined Fe₃O₄@SiO₂ with multi-walled carbon nanotubes on the surface.The adsorbent wasapplied to adsorption dyestuffs in water.The effects initial concentration,adsorption time and pH value of congo red were investigated.The results showed that the adsorption capacity increased with the incresed initial concentration and temperature.The adsorption capacity reached the maximum value at pH 5.The adsorption date well with the pseudo-second order kinetic model.The isothermal adsorption results shows that adsorption congo red on magnetic multiwalled carbon nanotubes is fitted well with both Langmuir and Freundlich isothermal model.The adsorption thermodynamics shows that the adsorption process is spontaneous and endothermic process,which belongs to the physical adsorption.The adsorption process is irreversible.