Formation And Properties Of Diatomite Based Porous Materials

Diatomite?SiO₂·nH₂O?is a naturally occurring substance which has many channels in it.Moreover,because of its relative low cost and abundance,it is utilized extensively in many fields.But it is difficult to form because of friability.By joining other additions,it is possible to fabricate into porous materials with well-defined macroscopic shapes and high mechanical stability.In this investigation,samples of diatomite and other additives were subjected to two forming methods which were dry pressing and slip casting.The performance of the materials samples were then determined by X-ray diffraction,scanning electron microscopy,and the specific surface area and pore size distribution of instrument,respectively.The results indicate as follows:?1?The samples of dry pressing method were subjected to a constant pressure,the content of diatomite,sintering temperature and rate.Under the operating conditions just described,porous material samples had a porosity of 49.37%,a compressive strength of 21.1 MPa and a surface area of 2.1403m²/g.Combined with the image changes and the morphology,the forming material had successfully retained the original structure of earth,and the earth particles and other particles were combined together to form a three-dimensional pore structure,which was organically combined together.?2?The pore forming mechanism of samples mainly includes the formation of liquid phase,the generation and growth of pores,and the overflow of pores.The generation of pores is mainly reflected in two temperature ranges,one is 300 to 900?,pore formed by the burning of pore forming agent;the other is in the high temperature above 900?,pore formed by the supersaturated precipitation.?3?The samples of grouting method were subjected to control the slurry pH value,add appropriate dispersant and regulate slurry solid content.The viscosity of the slurry is 380mPa·s.The samples of high yield have obtained.The porosity of sample was 54.01%and the compressive strength was 11.8MPa.?4?The removal rate of methylene blue solution prepared by two different molding methods can reach about 75%,which has good adsorption effect.It can be used as a single adsorbent or as the carrier,loading the other functional materials.