Effect of Stirring Rate and Functionalization Method on the Synthesis of Spherical Silica Particles Encapsulated Amine Moieties

Abstract

Silica nanocapsules (SiNC) utilization as adsorbent in pollution control have gained much attraction as SiNC are highly porous, have high surface area, excellent thermal and mechanical stability and a tuneable physicochemical property. In this study, microemulsion technique was used to synthesized SiNC. Effect of stirring rate as well as the effect of different method of amine functionalization i.e. grafting, wet impregnation, co-condensation, on the physicochemical properties of SiNC were studied. The stirring rate have significant effect on the physical properties of the SiNC. As the stirring speed increased from 200 rpm to 600 rpm, the particle diameter and the surface area decreases, 695 to 600 nm and 773 to 654 m2/g, respectively. The SEM and TEM analysis shows higher stirring rate produced surface with extensive damage while lower stirring rate produced a smoother surface. Different functionalization method affected the amount of amine groups incorporated into the SiNC. The FTIR spectra shows that the impregnation method incorporates higher amount of amine as indicated by the higher peak transmissions in the region 3450 – 3250 cm-1. However, amine functionalization of SiNC resulted in decrease of surface area as surface pore of the SiNC were occupied by the amine moieties’ molecules. The optimum condition for synthesizing amine functionalized SiNC were determined to be at stirring rate of 450 rpm through wet impregnation method as the SiNC produced were of spherical shape with smooth surface, and a relatively high surface area of 695 m2/g and pore diameter of 601 nm. These physicochemical characteristics shows the synthesized amine functionalized SiNC have promising qualities for application as adsorbents.