Study On Preparation Of Organic Titanic Acid And It's Adsorption Behavior For Dyes

In our country, titanium resource is especially abundant, which is ranked in the top among all counties in the world. Therefore, it provides an opportunity to intensively develop the titanium based industries. As one of semiconductors, titanic acid or salt has a layered structure and a large amount of studies focused on its application in the photo-catalysis. However, the study on its adsorption behavior has seldom addressed as it's adsorption capacity for organic pollutants is low.In this study, the solid-phase reaction between K₂CO₃ and TiO₂ was used to prepare the precursor K2Ti₄O₉. H₂Ti₄O₉ was further prepared by subsequent acid exchanging of K₂Ti₄O₉ with HCl solution. The organic titanate acid was obtained by the intercalation of organic amine. The resulting materials were characterized using X-ray diffraction (XRD) and IR spectroscopy, by which the structure of those materials was confirmed. Results showed that the resulting organic amine intercalated layered hybrid compounds had a larger interlayer space compared to their precursor, the layer distance is added to 3.75nm from 0.9nm . Those intercalated materials were resulted from an acid-base reaction between the amino group of the organic amine and the acid sites of titanate acid. Simultaneously, the hydrophobic groups were located between the interlayer of titanate acid and the layers of organic titanate acid were stabilized by the interaction between hydrophobic groups. This specific structure of the organic titanate acid led to an enhanced adsorption capacity compared with its precursor.The static adsorption study revealed that the organic modification of titanate acid led to a marked increase of its adsorption capacity. At 308K, the maximum adsorption amounts of the organic titanate were found to be 590mg/g, and 144.5 mg/g for Acid Red and Alizarin Red, respectively. Simulation results showed that increasing the adsorption temperature led to the increase of the maximum adsorption amount of Acid Red and Alizarin Red on the organic titanic acid, which indicating the adsorption process is endothermic and higher adsorption efficiency can beachieved at higher adsorption temperature. The experimental results also indicated that a strong hydrophobic interaction occurs between dye molecules and the organic titanic layers after dye molecules penetrate into the interlayer of the organic titanic acid, which results in the separation of the layers of the organic titanic acid. This process consequently led to the generation of a new hybrid complex consisting of single layer of the organic titanic acid and dye molecules. Furthermore, the properties of dye molecules controlled the adsorption efficiency of the organic titanic acid. Higher adsorption efficiency can be achieved for dye molecules with higher hydrophobicity.Note that one of the major drawbacks limiting the extensive application of the adsorption materials, in particular, organic clay, in the treatment of the wastewater is their regeneration and reuse after adsorption of the pollutant. Therefore, this contribution is aimed at the regeneration and reuse of the semiconductor based adsorption materials using photocatalytic techniques to decompose the adsorbed pollutants.The reuse of the used adsorbent was finally attempted using UV irradiation. UV-DRS spectra of the post-treated materials showed that the adsorption amount of the Acid Red was markedly reduced, which could be ascribed to the degradation of the dye upon UV irradiation. This suggests that the dye loaded materials can be reused after UV treatment. Further study on the recycle of the used adsorbent is currently under investigation.