| Phenols are important intermediates to produce dye and pharmaceutical, being widely used in various fields of industrial production. A large number of wastewater containing phenol from industrial emissions, it has a high organic concentration. Phenols belong to difficult degradation of persistent organic pollutants(pops). Source of Phenols is extensive and pernicious. If the industrial wastewater containing phenols pollutants which is mutagenic,teratogenic and carcinogenic exposure in the human living environment, it will not only cause serious pollution to the environment, but also seriously damage to health of human. Therefore improving the processing technology of wastewater containing phenols and establishing effective method to degradate phenols in wastewater is an important task to protect the environment and bring benefit to mankind.The advanced oxidation processes(AOPs) have succeeded in degradating of the organic compound in polluted water. The thesis mainly using ultrasound combined with NiO/AC and UV photocatalytic combined with NiO / AC respectively degradate phenols in wastewater.NiO/AC catalysts were prepared by chemical coprecipitation process. NiO/AC catalysts were characterized by means of XRD, SEM. The Results show that diffraction peak position part of NiO/AC nanomaterials is accurately, which is big corresponding standard card and the crystallization is high. Most of Ni(OH)2 would be generated into the NiO anatase. The result of SEM micrograph shows rodlike and spherical NiO pirticles are spread evenly over the surface of the activated carbon. There are part of the catalysts cluster to agglomerated structure. The particle size is small. Clusters particles of NiO within a large number of pore and structure defect providing a large number of active center, which create advantageous conditions for degradation organic matter.Ultrasonic combined with NiO/AC degradates five kinds of phenols in wastewater(p-chlorophenol, aminophenol, p-aminophenol, resorcinol, p-nitrophenol). Through the research of the degradation, first we choose the best degradation effect of NiO/AC,then investigate the influence of dosage of catalyst, ultrasonic power, pH value of the solution,concentration of the solution. Results showed that ultrasonic method combined with NiO/ACdegradate p-chlorophenol, aminophenol, p-amiophenol, resrcinol, p-nitrophenol, the degradation rates are all more than 90%. Photocatalysis combined with NiO/AC catalytic oxidate p-chlorophenol, aminophenol, degradation rate reaches above 80%.Through analyzing intermediate products of p-chlorophenol and aminophenol from degradation process, preliminary discussed p-chlorophenol and aminophenol degradation mechanism. The process of the p-chlorophenol inclued: hydroxylation of p-chlorophenol,aromatic compounds ring opening to aliphatic compounds, organic acid oxidation for inorganic small molecules. Reaction mechanism of ultrasound combined with NiO/AC divided into two parts, free radical oxidation and high temperature pyrolysis. But the process of photocatalytic also produces large quantities of superoxide anion replace carbon on p-nitrophenol by nucleophilic substitution, labile intermediates from nucleophilic substitution generate into resorcinol or pyrocatechol.Compared with ultraviolet light catalysis, the degradation rate of p-chlorophenol under ultrasonic method is faster, and the decomposition rate of intermediate products is faster, too.But the results showed catching intermidiate products’ type is less. The phenol pollutants can be oxidated o-benzoquinone and 2-benzoquinone and then ring open to organic acid, which further degradation and mineralization eventually generate CO2, H2 O and small molecules. |
