Mesoporous silica SBA-15 for natural antimicrobial delivery

Mesoporous silica SBA-15 was synthesized for controlled release applications of the natural antibacterial, allyl isothiocyanate (AITC). Two different molar ratios of silica were used as 1.00 (SBA-15a) and 0.74 (SBA-15b). This 26% reduction gave the same parallel-sided cylindrical pore shapes, but increased the mean pore width 38% and pore volume 37%. Adsorption of AITC from vapor phase resulted in liquid adsorbed phase, confirmed by Fourier transform infrared spectroscopy. Both silica samples were filled to 100% capacity, with SBA-15b having a 39 mass% increase in amount adsorbed. More than 50% of the adsorbed phase was released by both samples in the first 12 h, with the desorption rate from SBA-15a > SBA-15b. After 24 h, the amount desorbed approached a maximum with 94% from SBA-15a and 87% from SBA-15b. Both sets of experimental desorption data were well-correlated by a diffusion from a plane sheet model incorporating intraparticle porosity. An effective diffusion coefficient for AITC was extracted from the model for SBA-15a as 4.40 × 10− 16 m2/s, and 3.00 × 10−16 m2/s for SBA-15b, a 32% decrease.