The Research On Extraction And Adsorption Properties Of The Thalassiosira Weissflogii Frustules

Diatoms with amazing micron or nanoscale silicon dioxide membrane structure (called frustules) are unicellular marine organisms.It has more than 100000 categories, various sizes and shapes. The frustules has attracted much attention because of its precision structure, many pores,high specific surface area and high toughness. In this paper, we explore the best parameters of the diatom(Thalassiosira weissflogii) in the laboratory, under the conditions of temperature of 30℃ and pH 9, which is better to the growth of Thalassiosira weissflogii.Take the Thalassiosira weissflogii that cultured by laboratory as an example, to explore the extraction method frustules and best parameters. Using pickling and calcination methods,10% hydrochloric acid washed for 1h, dried and calcined 6 h at 600℃ can obtain high-quality frustules. Than using TGA, SEM, EDX, XRD, BET to analyse the characterization. SiO2 which is amorphous, more than 90% SiO2 in weight can be obtained. The surface area is 348.21 m2/g (much higher than the diatomite). The high quality diatomite (SiO2 content more than 90%) and Thalassiosira weissflogii frustules were utilized as adsorbents for the removal of Methylrosanilnium Chloride and Rhodamine B dye, and various effects of these two factors on the absorption process as a whole. It is conducive to the frustules cationic dye adsorption when it under alkaline condition. We can get a good feedback of recycling by 150℃ drying of adsorbed frustules. Frustules dye adsorption effect is much better than diatomite, the removal of both dyes can reach more than 90%. By adsorption kinetics model isotherm model, isotherm model, the thermodynamic parameters of the frustuless to fitting analyse the diatomite dye adsorption process and get the dye adsorption mechanism. The results showed that the dye adsorption process are more in line with the pseudo-second-order kinetic model. Adsorption isotherm is more in line with the Langmuir model. Adsorption contains liquid film diffusion, diffusion particles and surface adsorption. The adsorption process is spontaneous endothermic process. The maximum amount of frustules and diatomite are 152.316 mg/g and 15.663 mg/g. Frustules absorption effect is much better than diatomite.