Biogenic silicon dioxide nanoparticles processed from natural sources

Abstract

The main purpose of this study is to obtain the biogenic silica nanoparticles from selected types of plants and thorough characterization. Plants create SiO2 nanoparticles while growing from the colloidal solution of orthosilicic acid contained in the soil. Together with acid, they absorb additional ions that are essential for their growth, which was found using SEM and EDX analysis. The organic part of the plants was removed using a two-step method. Firstly, the plants were purified in 10% HCl in order to remove undesirable ions. Next, the optimal degradation temperatures were determined according to TGA results that varies between 500–650 °C. After the above-mentioned processes silica was studied using ICP-OES, FTIR, TEM, and N2 adsorption. The nanoparticles obtained from the investigated kinds of plants showed an amorphous structure, differed in size (from 8 to 20 nm) and are not purely symmetrical in any of the investigated samples. Estimated content of SiO2 nanoparticles was in the range 11.5–25.3% depending on the sample. The specific surface area was measured using the BET method.