Synthesis of SiO₂ nanoparticles assisted by thermocavitation in natural dye (Hibiscus sabdariffa L.)

Silica nanoparticles (SiO2) were synthesized via thermocavitation. The high pressures and temperature generated after implosion of the cavitation bubble improved the conditions for nanoparticles synthesis. Solutions of 3(trietoxysilyl) propyl isocyanate (TESPI) and a natural dye (Hibiscus sabdariffa L.), extracted in ethanol, were used as starting materials. To obtain different reactions, TESPI volume was varied in the solutions. The results show that the natural dye was added to nanoparticles; in addition, the number of nanoparticles linearly correlated with the volume of the TESPI used in the solution. We observed the morphologies of nanoparticles with optical microscopy (OM), atomic force microscopy (AFM), and scanning electron microscopy (SEM). SEM images show that the size distribution was bimodal, with nanoparticle sizes in the range of 1 ism to 20 ism. The predominant size of the nanoparticles was approximately 2.37 ism.