The Preparation Of Magnetic Catalysts And Their Study Of Dye Wastewater Degradation Of Adaptation Process

Water pollution is continuously a environmental problem attracting much more attention. Especially dye wastewater is a high density waste water contain large volumes of organic matters from dye production and application industries, it was not only cause water eutrophication, disturb the growth of aquatic organisms, but also maybe a aesthetic pollution.CWPO is a kind of effective oxidation technology of wastewater with high concentration and poisonous, the key problem of which is a high-effective catalyst research. Recent years, activated carbon has increasingly been used in dye wastewater treatment because of the excellent adsorption properties. Adsorption effect was proven to be markedly ineffective for handling wastewater containing synthetic dyes. It based on physical processes, although effective for color removal in many cases, merely transfer pollutants to the other media causing secondary waste. While, the above limitation can be overcomed by the exploration research of the more effective materials of modified activated carbon, which has been proposed in current development of water treatment. The overall efficiency of modified activated carbon can reduce the cost of activated carbon and improve its utilization. Much research effort has been launched on the modification of activated carbon. Impregnating AC in the metal ion solution is one of good methods, which improve the surface pore size distribution and chemical activity, even the catalytic properties of modified AC catalysts. In catalytic wet peroxide oxidation (CWPO) process, the catalysts are used to generate hydroxyl radicals in the presence of hydrogen peroxide for the oxidation of wastewater with high organic content. Whereas, the materials utility also limited by the difficulty of solid-liquid separation. The traditional filtrated separation can easily lead to mesh blocked and the loss of activated carbon. To overcome these drawbacks, magnetic separation, as a simple and efficient separation method, has gradually been studied and used in water treatment. The magnetic activated carbon, which was prepared by incorporating magnetic particles on powdered activated carbon, can be manipulated by external magnetic field. Thus the separation problem can be solved. Moreover, it can provide a potential advantage to the materials’recovery and reuse in this process. The objective of this study is to prepare a catalytic material with good magnetism for use in CWPO. By incorporation of manganese ferrite particles (MnFe2O4) on AC surface to prepare the magnetic activated carbon (MAC). Then the MAC was impregnated with copper ion solution at various concentrations and followed by calcination. The obtained catalysts were used in the CWPO of synthetic dye wastewater containing Direct violet (D-BL). Meanwhile, the effect factors have been discussed in the MCAC preparation process and the dye decoloration process. Magnetism, stability and reusability of the catalyst were also tested.In addition, temperature is an important effect factor on dye degradation. The temp of reaction system is generally heating in water bath, first heating to solution phase and then transfer to solution-liquid interface in the traditional CWPO. If can greatly increase the reaction temperature of the interface, the degradation of the dye efficiency will be higher. The magneto caloric method is the key to solve this problem. Therefore, in this lab built magnetic hot devices on magnetic material thermal properties and magnetic hot magnetic method of the degradation of the dye performance discussion. The results show that:(1)By incorporation of manganese ferrite particles (MnFe2O4) on activated carbon surface, the magnetic activated carbon (MAC) was prepared, and the MAC was impregnated with copper ion solution at various concentrations and followed by calcination to obtain MCAC. The MCAC presented an effective activity in decoloration of synthetic dye wastewater containing Direct Heliotrope (D-BL). The SEM/EDX observation identified the metal element were well dispersed and bound in the carbon matrix. The XRD patterns of the MCAC also verified that CuFe2O4as the main catalytic phase play roles in reaction. The H2O2dosage is the important factor to dominate the decoloration rate in CWPO process. The experimental results also showed that the materials have good magnetism under the optimum preparation conditions.(2) In the static CWPO experiment of the decomposition of Direct Heliotrope (D-BL), MCAC catalysts can obtain decoloration percentages of86.05%in5h at45℃, when the solid/liquid is1/300(g/mL) with H2O2dosage of5.22mol L-1. The pH plays a more important effect in the H2O2oxidation process and H2O2decomposed to-OH Radical by the existence of H+. Besides, dye decoloration rate increased gradually with the increase of NaCl salinity, while the reaction system with added Na2SO4was just the opposite. (3) In addition, desorption experiment proved that MCACs has good reproducibility and stability, as well the most of the adsorbed dyes can be desorbed by1.5moL L-1NaOH solution. In the reaction system without adding H2O2, the dye decoloration rate decreased gradually in5cycles. While, in the experiment with adding H2O2, the decoloration rates are basically remain steady, implying directly that the MCAC possessed good reusability.(4) The continuous filtering experiment shows the decoloring ability of MCAC on Direct violet (D-BL) is34mg g-1, and the highest percentage can up to99.50%(5) In order to investigate the magnetic thermal property of the material and magnetic thermal degradation characteristic of the dyes, the laboratory-made magnetic reactor was made. The energy flow diagram of magnetic reaction shows that, there is a linear relationship between the change in the value of temperature of the solution and the magnetic heat. And the higher values of temperature of solution, the greater temperature of the material surface will be. Besides, the distilled water as the feed solution in homemade magnetic reactor shows that water maximum temperature was45.9℃, which was increased about20degree, and the thermal equilibrium time is about23min. The qualitative derivation shows the surface temperature is much higher than that of the solution phase. In addition, higher temperature of effluent water and longer thermal equilibrium time can be reached in the greater quality of the magnetic filler MCAC. Size of the filler material on the water temperature and the thermal equilibrium time is not obvious, but better dying effluent solution can be acquire by smaller particle size and higher influent water temperature.