Điều chế vật liệu nano SiO2 cấu trúc xốp từ tro trấu để hấp phụ xanh metylen trong nước

Abstract

Mesoporous silica nanoparticles was extracted successfully from rice straw ash (RSA) by using sodium hydroxide solution to produce a sodium silicate solution and then precipitated by adding HCl solution until the pH value about 3. The prepared products were characterized by EDX, XRD, SEM, TEM, FT-IR and BET methods. It was found that the optimal synthesis conditions for the preparation of SiO₂ nanoparticles in the weight ratio RSA/NaOH = 1/2.4, respectively and products were calcined at 550^oC in 2h. In this condition the obtained SiO₂ powders were monoclinic crystal system, mesoporous structure and large specific surface area (258.3 m²/g). Moreover, the performance of nanosized SiO₂ powders was tested by the adsorption of methylene blue in a batch system under different adsorbent dosage, different initial dye concentrations and different pH values. The results show that the maximum adsorption capacity was 20.41 mg.g^-1 and a high pH is favorable for adsorption. Further, equilibrium isotherms of the adsorption of methylene blue on SiO₂ fit well to both the Langmuir model and Freundlich model.