The Bentonite Modification, characterization and Application
|School||Shaanxi Normal University|
|Course||Physical and chemical|
|Keywords||adsorption oxidative degradation inorganic-organic modifiedbentonite methyl orange dye wastewater phenol wastewater|
All the time, water pollution is a global problem which was focused on by the public. And with the rapid development of society and the improvement of the level of industrialization, dyeing and printing industry is also developing rapidly. The water pollution caused by dye is immensely. There are a wide variety of modern dyes and most of them have resistibility to long-term exposure to sunlight, water, and other atrocious conditions. Azo dyes are one of the important classes of commercial synthetic dyes. And because of their solubility, low cost, stability and color variety, they are widely used in a number of industries. Azo dyes are well known carcinogenic organic substances. Once they enter the body, reductive enzymes in the liver can catalyze the reductive cleavage of the azo linkage to produce aromatic amines and can lead to intestinal cancer. In this thesis, the aqueous solution of methyl orange was selected as the simulated dye wastewater, its treatment by the inorganic-organic modified bentonite synthesized by immersion and solid phase grinding method, were investigated, and the catalyst synthesized by the latter method was also applied to the degradation process of phenol wastewater.In the first part, the characteristics and properties of dyes were introduced, the harm of dye wastewater, the status and methods of dye wastewater treatment were reviewed in detail, in special, the application of bentonite were emphasized. Finally, the purpose, content and innovation of this research were presented.In the second part, the preparation of Al/CTAB-bent and the application of response surface method were introduced, more than99%methyl orange (MO) and methylene blue (MB) can be removed by Al/CTAB-bent.In the third part, the effect of various factors on MO adsorption with Al/CTAB-bent were discussed, and the optimal conditions were obtained:contact time30min, adsorbent dosage0.5g, initial pH≥3, reaction temperature293K, MO initial concentration100mg L-1, the result showed that the decolorization of MO was above99%. The data agree well with the second-order kinetic model and the Langmuir adsorption isotherm model. And the adsorption thermodynamics indicate that the adsorption of MO onto Al/CTAB-bent is spontaneous and exothermic.In the fourth part, KMnO4/CTAB-bent by solid phase grinding method were prepared and used in treatment of MO dye wastewater. The synthetic factors were studied, and a mixture of bentonite, KMnO4and CTAB in a100:60:17mass ratio were obtained and the best performance was shown at activation time2h and383K. The results showed that at low pH, the oxidation dominated during the process, while adsorption became stronger with the increasing of pH; and higher temperature decreased the adsorption process. The data of MO adsorption agree well with the pseudo-second-order kinetics and the Freundlich adsorption isotherm model. And the adsorption thermodynamics indicate that the adsorption of MO onto KMnO4/CTAB-bent is spontaneous and exothermic. KMnO4/CTAB-bent was demonstrated to have good stability and reusability for MO removal from wastewater.In the fifth part, KMnO4/CTAB-bent was applied in phenol degradation. It was found that the activation temperature has effect on the performance of catalyst and the best activation temperature was383K. The results show that pH is an important factor which influences the degradation process of phenol in the presence of KMnO4/CTAB-bent, when pH=2, the oxidation dominated all reaction, while adsorption became stronger with the increasing of pH; and higher temperature decreased the adsorption process. The stability of KMnO4/CTAB-bent needs to be improved for phenol degradation.