Preparation And Properties Of Ca-Al Composite Metal Hydroxide Porous Materials

In the process of industrial production and application,chloride ions can easily flow into water bodies to form a large amount of high-chlorine ion wastewater.The excessive concentration of chloride ions in wastewater will cause many hazards and have a serious impact on human life.Therefore,high-chlorine wastewater must be treated reasonably and effectively.Layered double hydroxides(LDHs),commonly known as hydrotalcites,are a kind of cheap and easy-to-obtain anionic adsorbents.The adsorption performance of the LDHs material is greatly affected by the specific surface area and the layer types of the materials.Accordingly,the development of a new strategy for construction of LDHs materials with higher adsorption properties still remains an attractive and promising goal.In Chapter 3,it is proposed to prepare LDHs porous materials with different types of metal layers and improve the specific surface area of the materials to obtain LDHs materials with higher adsorption performance.In the preliminary experiments,it was found that Ca-Al-LDHs powder materials had better adsorption performance for chloride ions.Hence,it was used as a reference to further improve the adsorption performance of the materials.In this study,the composite aerogel material with silica aerogel as the framework and Ca-Al-LDHs nano-wafer supported on the silica aerogel was successfully prepared.The test results showed that Ca-Al-LDHs powders were successfully peeled into nano-sheets in the dispersion stripping systems and they were stably existed in the aerogel supported by silica skeleton.Therefore,the adsorption activity sites were greatly increased and the unit adsorption amount of chloride ion of the materials increased from 31.6 mg/g to 48.12 mg/g.In Chapter 4,we further explored and studied the preparation of new materials with Ca-Al-LDHs as the framework of aerogel,which was using alumina aerogel system as in-situ synthesis template.The structures of the Ca-Al-LDHs aerogel samples were characterized by SEM,XRD and BET methods.The results showed that the aerogel was successfully synthesized with Ca-Al-LDHs grain as the skeleton of porous structure.Moreover,the specific surface area of the sample increased from 2.59 m~2/g to 102.96 m~2/g.Since Ca-Al-LDHs grains were directly involved in the growth of aerogel framework,the adsorption equilibrium could be quickly reached at 3 h after adsorption.In addition,when the temperature increased,the adsorption capacity of chloride ion increased distinctly(41.3 mg/g,60?,500 ppm).