Research The Salix Mongolica Used In Preparation Of Porous Ceramics Based On Fly Ash

Porous ceramics not only has the excellent properties of ceramic products, but also has a large porosity and specific surface area, and stability excellent characteristics and so on. These excellent properties of porous ceramic materials make itself for special use in the social life. In this paper, using the feature forestry resources of salix branches in Inner Mongolia and the fly ash as the main materials in preparation of porous ceramic adsorbent, with the purpose of providing a new research field for the feature of forestry resources in Inner Mongolia and the use of fly ash, and providing a new approach for the development of porous adsorption materials.The fly ash samples which come from coal chemical industry were analyzed via the characterization methods of EDS and XRD, and the results show that and the main chemical components of fly ash residue are silicon oxide and aluminum oxide, the material composition conforms to the preparation of porous ceramics. Based on the practical situation of Inner Mongolia, use the Salix Mongolica powder as pore-forming agent in the test of the preparation of porous ceramics, which get from the branches of salix after chopping down. Making heating system of porous ceramics refer to thermal decomposition process of additives by TG and DSC analysis, exploring the molding pressure, the adding quantity of pore-forming agent and the time of heat preservation on the influence of porosity. Through the response surface method to get the optimal preparation process parameters.The porous ceramics samples were used for adsorption Pb2+, studying the initial concentration of Pb2+, the pH, the adsorption time and the adsorption temperature influence on the adsorption amount. The adsorption experiments were optimized by response surface method again, in order to get a better adsorption process parameters. The solution concentration of HNO3, the time and the temperature are the influencing factors, exploring the recycle rate of adsorption by the porous ceramic which is based on fly ash. By scanning electron microscope (SEM) and pore specific surface analyzer, analyzing its morphology structure, specific surface area and pore distribution.The research results of this paper were summarized as follows:1. Using the fly ash which comes from coal chemical industry as the experimental material, combined with the traditional method of preparation of porous ceramics, and make the salix (Salix Mongolica powder) as the pore-forming agent, adding a certain amount of binding agent and sintering additives, after pressing, ageing and calcining under certain conditions to get the final sample. With the help of porosity of the sample as response value, optimized by response surface method, getting the optimal preparation process parameters. The results show that when the forming pressure is 10 MPa, heat preservation time is 2h, and pore-forming agent content is 15 wt%, the porosity of product is 34.23%, we can see the surface of the sample is irregularity, flocculent, loose and porous by scanning electron microscope (SEM).2. Used the porous ceramic material based on fly ash in adsorbing Pb+, which gets from the optimal process conditions, by studying the initial concentration of Pb2+, the pH, the temperature and the time in adsorption impact on the adsorption quantity. The adsorption process are optimized by the response surface method on the basis of single factor experiment, and the results show that when the concentration of Pb2+ is 0.03 mol/L, the pH value is 5.5, the adsorption time is 80 min, the adsorption temperature is 30℃, the adsorption quantity can rise up to 334.24 mg/g, it is not only economic and environmental protection, but also the technology is feasible.3. The desorption experiment is to explore the recycling of porous ceramic material, via exploring the solution concentration of HNO3 and stripping, the time and temperature of desorption effect on the desorption quantity, the results show that when the concentration is 0.05 mol/L of HNO3 solution, the desorption time is 25 min, the desorption temperature is 30℃, the adsorption quantity can reach to 91%.4. Using the specific surface analyzer to explore the adsorption mechanism of porous ceramic, and the results showed that the adsorption mechanism of porous ceramic conforms to the Ⅲ type isotherm which is a rare type of isothermal adsorption. The force between adsorbent and adsorbate is very weak, and there has formed multilayer adsorption on the surface of the adsorbent before forming a complete monolayer. BET specific surface of the porous ceramic sample which according to the optimum preparation process was 8.64 m2/g, and according to the BJH picture of pore size distribution, the pores are most between 2 nm-50 nm, which is called mesoporous.