Synthesis Of Magnetic Polyacrylic Acid Materials And Its Application In Wastewater Treatment

The magnetic polymer microspheres with special environment sensitive and excellent magnetic response has broad application in wastewater treatment due to their unique physical and chemical properties. Then, a series of problems such as easy oxidation, complex of reaction device limit their application in water treatment. Herin, Fe₃O₄@SiO₂@PAA particles with uniform size, stable performance and dual response properties were synthesized using reflux precipitation polymerization（RPP） method and Fe₃O₄@Si O₂@CS/PAA particles were produced by a simple method to introduce amino groups. The particles were used for methylene blue and Cr（VI） removal as absorbents respectivelyMonodisperse Fe₃O₄@SiO₂@PAA particles were produced through RPP method including a Fe₃O₄ core using solvent thermal method, a silica layer using St?ber method, a polyacrylic acid shell. The RPP method is an effective method to synthesize hydrophilic polymers adding with short reaction time, simple experimental device and easy to control of the process. The obtained particles were characterized by X-ray diffiraction, Fourier transform infrared spectrometer, scanning electron microscope, transmission electron microscope, vibrating sample magnetometer, thermogravimetric analysis. The results indicated that the diameter of magnetic microspheres was 470 nm.This part aimed at the removal of methylene blue from aqueous solution using Fe₃O₄@SiO₂@PAA as absorbent. The removal rate increased with the increased of pH due to exist of massive carboxyl groups on the surface of particles. The adsorption reached balance within 5 min owing to lack of internal diffusion between Fe₃O₄@SiO₂@PAA particles. The adsorption process follows pseudo-second order kinetic and Langmuir model can describe the isotherm date well. The adsorbent has a high recycling rate.Fe₃O₄@SiO₂@CS/PAA particles were synthesized using a facial and simple method combining CS and AA. The obtained particles were characterized by X-ray diffiraction, Fourier transform infrared spectrometer, scanning electron microscope, transmission electron microscope, vibrating sample magnetometer, thermogravimetric analysis. The results show the diameter of particles were 460 nm including a Fe₃O₄ core, silica layer, CS/PAA shell, with amino, carboxyl, hydroxyl groups on the surface of particles and good magnetic responsiveness.This part aimed at the removal of Cr（VI） from aqueous solution using Fe₃O₄@SiO₂@CS/PAA as absorbent. The experiments indicated that pH=2 and t=75 ℃ as the optimum conditions and the adsorption eauation reached within 180 min. The adsorption process follows pseudo-second order kinetic and Langmuir model can describe the isotherm date well. The Cr（VI） was removed by electrostatic interaction and ion exchange, the adsorption rate was controlled by external and internal diffusion.The thermodynamic parameters ?H、?S>0 and ?G<0 indicated that the increase of temperature is favorable for the adsorption process and ?S is the driving force of this process.