NiFe_2O_4磁性纳米颗粒的制备及其催化降解孔雀石绿的研究

Preparation of NiFe_2O_4 Magnetic Nanoparticles and Its Catalytic Degradation of Malachite Green

以溶胶-凝胶法和固相研磨法制备NiFe_2O_4磁性纳米颗粒,采用X射线粉末衍射仪、扫描电子显微镜、透射电子显微镜、X射线光电子能谱仪、震动样品磁强计等探讨了不同合成方法对其结构、晶型、形貌的影响,结果表明凝胶-溶胶法制得的NiFe_2O_4具有颗粒小、尺寸均匀、磁学性能优、催化性能好等特点。推测了NiFe_2O_4/H_2O_2类芬顿体系催化降解孔雀石绿的反应机理。考察了pH值、催化剂用量、氧化剂用量、反应时间等因素的影响,结果表明:对浓度为25 mg/L的孔雀石绿溶液,当NiFe_2O_4用量为0.05 g,H_2O_2用量为0.30 m L,pH为5,温度为298 K,反应时间为45 min,孔雀石绿脱色率在93%以上。动力学研究表明降解过程近似为一级反应,速率常数达0.057 min-1。

NiFe2O4 magnetic nanoparticles were prepared by sol-gel and solid phase grinding method. The effect of different synthesis methods on the structure,crytallinity and morphology were also discussed by XRD,SEM,TEM,EDS and VSM. The results show that NiFe2O4 prepared by sol-gel method had small particle size,uniform dimension,excellent magnetic property and good catalytic performance. The mechanism of catalytic degradation of malachite green（ MG） by NiFe2O4/ H2O2 Fenton-like system was speculated according to the results of X-ray photoelectric spectroscopy analysis. The effects of initial p H,catalyst dosage,oxidant dosage and reaction time on the degradation of MG were researched. The experimental results indicated that 93% decolorization rate of 25 mg / L MG solution was achieved within45 min under the conditions of 0. 05 g NiFe2O4,0. 30 m L H2O2,pH value of 5 and the temperature of298 K. Kinetic studies showed that the decolorization process was coincidence to the first-order kinetic equation and the reaction rate constant was 0. 057 min^-1.