The Preparation Of Tio2 / Ramie Fiber Composite Materials And Its Photocatalytic Degradation Of Dye Wastewater

In recent years, with the development of economy, the environmental pollution problems have become even more serious. Due to its chemical stability, insoluble, corrosion-resistant, non-toxic and cheap, pohotocatalyst-TiO2has been paid much attention and widely used in photocatalytic reactions. However, TiO2is difficult to recover due to its small particle size, also its photocatalytic activity and efficiency of photon are low. In order to fix these weaknesses, researchers have been tried to load TiO2on large-surface area materials, such as fiber and fabric. Ramie fiber is mainly produced in China, and has a large yield in fiber production. The present thesis studied the TiO2/ramie fiber composite, including the following four parts:(1) Based on the solvent evaporation and crystallization, we prepared well-dispersed and high-crystallinity titanium dioxide. A saturated solution of butyl titanate as a precursor of Ti was prepared by diluting and hydrolyzing of butyl titanate, which was sealed with a plastic film, and then was transferred into an oven at80℃for4d. After that, the highly dispersed titanium dioxide with anatase phase was obtained. The effects of volumetric ratio of titanium tetrabutoide (Ti(OBu)4) to deionized water and tetrabutoide (Ti(OBu)4) to hydrofluoric acid were investigated. The results indicated that the volumetric ratio of titanium tetrabutoide (Ti(OBu)4) to deionized water had no effect on the morphology of titanium dioxide, but volumetric ratio of tetrabutoide (Ti(OBu)4) to hydrofluoric acid had obvious effect on the crystallinity of titanium dioxide. When the volumetric ratio of tetrabutoide (Ti(OBu)4) to hydrofluoric acid was2:1, the crystallinity of anatase reached the maximum. This method used has many excellent characters, such as a simple process, low energy consumption and no sintering, at the same time it solve the problem of aggregation.(2) Using a physical dispersion method, titanium dioxide/ramie fiber composites were prepared. The composites were characterized by XRD and SEM techniques. The results indicated that titanium dioxide was not firmly supported on the composites as prepared via the physical dispersion method. After several times of washing, the titanium dioxide supported on the composites surface was almost removed. Although, the method is simple, its recycling rate is low.(3) Using a chemical combination method, titanium dioxide/ramie fiber composites were prepared. Firstly, the ramie fiber was modified via carboxymethyl reaction; secondly, a slow hydrolysis of tetrabutoide (Ti(OBu)4) on the surface of carboxymethyl cellulose was occurred, then it was put into boiling water for crystallizing. Finally, a titanium dioxide/ramie fiber composite with chemical bonds combination between titanium dioxide and ramie fiber was synthesized. The effects of weight ratio of sodium chloroacetate to ramie fiber and refluxing temperatures were investigated. The titanium dioxide/ramie fiber composites were characterized by XRD and SEM techniques. The results indicated that titanium dioxide was well-dispersed on the surface of the composites. After several times of washing, the titanium dioxide was still firmly loaded on the surface of composite, which indicated that this method fixed well the drawbacks of the composites prepared by the physical dispersion method.(4) We investigated the photocatalytic performance of composites prepared by the chemical combination method. We selected methyl orange and rhodamine B as dye wastewater models. The results indicated that the composites had well photocatalytic performance and higher degradation rate than that of pure titanium dioxide. At the same time, photodegrading for methyl orange followed a zero order reaction, and photodegrading for rhodamine B included adsorption process.