Preparation And Modification Of Fe₃O₄/Polymer Composite Microspheres As Adsorbents For Magnetic Separation

Magnetic separation with composite microspheres presents an alternative strategyfor applications in biomedical or chemical fields. However, the synthesis of high-qualitycore–shell structured magnetic composites universally assumes the surfactant-directingand/or silica-assisting polymerization approach to modify and stabilize the magneticcores. In this aricle, core-shell Fe₃O₄/PANI and Fe₃O₄/PPy magnetic microspheres werefabricated by polymerization method under ultrasonic irradiation without using anysurfactant, cross-linking agent or organic stabilizer. The samples were characterized byXRD, FTIR, TEM, SEM, XPS, VSM. Acid-base titration was applied to determine thecontents of surface amino group. Base on amion group could react with anhydridemolecules through necleophilic reaction, make Fe₃O₄/PPy be modified toFe₃O₄/PPy–COOH. The samples exhibit high saturation magnetization, good dispersity,superparamagnetism, controllable shell thickness, the concentration of Fe₃O₄/PANI andFe₃O₄/PPy surface groups were267μmol/g,332μmol/g respectively.Fe₃O₄/PANI and Fe₃O₄/PPy were used as efficient sorbent for remove of Cr（VI）from water solution. Fe₃O₄/PANI show strong adsorption capacity with an adsorptioncapacity of about56.2mg/g,93.3%of the Cr（VI） could be removed; Fe₃O₄/PPy hasadsorption capacity of about26.7mg/g, about53.4%. The regenerated adsorbentFe₃O₄/PANI can be reused for two successive adsorption–desorption cycles withoutappreciable loss of its original capacity.Fe₃O₄/PANI、Fe₃O₄/PPy、Fe₃O₄/PPy–COOH were applied for extraction of DNA,find the best conditions of adsorption and desorption. which is confirmed by the agarosegel eletrophoresis and polymerase chain reaction （PCR） diagnosis. Theadsorption/desorption mechanism of DNA onto Fe₃O₄/PANI and Fe₃O₄/PPy werediscussed, the purified DNA with a high recovery ration, extracted genomic DNA couldbe successfully used for PCR. The results showed the magnetic isolation of genomicDNA with the composite microspheres shows superior to the conventionalphenol–chloroform extraction, can be successfully used for PCR.