The Degradation Of Azo Dye And The Permanent Magnetic Properties Of Amorphous/Nanocrystalline Magnetic Materials

Sewage treatment is a pressing environmental problem. Among the Advanced oxidation processes (AOPs) used in sewage treatment, Catalytic oxidation technologies, especially the Fenton-like technology, are the most effective ways in the non-biodegradation of organic sewage at the present since they exhibit some significant advantages, such as low energy consumption, purify compently and no secondary pollution, and so on. Metal glass (MG), also called as amorphous alloy, is a kind of metallic material with amorphous structure. The arrangement of atoms is local ordered, but long-range disordered, exhibiting a metastable thermodynamic characteristic. Comparing with crystalline, the metal glass has relatively higher energy, leading to a more activity in the statistical thermodynamics. Recently, it was reported that the metal glass powders can directly oxidize and degrade the azo dyes. This important discovery opened up a new application in sewage treatment for the metal glass. Magnetic metal glasses present some additional advantages, such as higher degradation efficiency, easy to recycle and avoid sencondary pollution. Therefore, in this dissertation, X-3B azo dye, an azo dye difficult to be biologically degraded, was chosen as a probe molecule. The degradation mechanism of X-3B Azo dye by various magnetic metal glasses was emphased on. The investigated magnetic metal glasses in this dissertation include Fe-based, La-based, Zr-based metal glasses, etc. The effects of different reaction ways, the initial pH value of solution, reaction temperature, reaction time, catalyst dosage on the decoloration of high concentration X-3B were investigated. The experimental results demonstrated that the Fe-based, La-based, Zr-based magnetic metal glass powders can degrade X-3B azo dye effectively.In addition, this dissertation also studied the preparation methods and permanent magnetic performance of nanocomposite NdFeB rare-earth permanent magnetic materials. Nanocrystalline (Nd0.75Dy0.25)10.5Zr2Fe82B5.5alloy was prepared by directly melt spinning, exhibiting good permanent performance. The effect of rapid quenching speeds (cooling rate) on the microstructure and magnetic properties of the (Nd0.75Dy0.25)10.5Zr2Fe82B5.5ribbons have been studied. It has been found that a uniform microstructure with fine a-Fe grains and R2Fe14B grains can be developed at an optimum wheel speed of about18m/s by directly melt spinning method. Without any heat treatment, the good magnetic properties are obtained, e.g. iHc=1027kA/m, mr=0.71,(BH)max=174kJ/m3.