Probing the use of Ag-modified SBA-15 as ethylene scavenger

Controlling the accumulation of ethylene is important in fruit and vegetable packaging. In this work, the potential use of Ag-containing SBA-15 mesoporous silica adsorbent as ethylene scavenger is studied. The adsorption capacity and affinity toward this gas are probing as a function of Ag content and Ag nanospecies present in the materials that were modified by successive thermal treatments at 200 and 350 °C in N2 and air atmospheres. The samples were characterized by X-ray diffraction, UV–visible, high-resolution electron microscopy and adsorption experiments. The results indicated that the treatment at 200 °C induced effective Ag+ dispersion and generated Ag0 nanoparticles and that a second annealing favored the formation of silver oxide nanoparticles and the reordering of silver and adsorption sites inside the SBA structure. The best overall ethylene adsorption capacity was obtained with the lower Ag content and thermal treatment at 200 °C without further annealing. The increase in the silver loading produced a decrease of ethylene adsorption by blocking of active sites and inhibiting π-interaction. Interestingly, the annealing at 350 °C in air induced a structural rearrangement in the adsorption sites that increased both their adsorption capacity and affinity toward ethylene, particularly at the pressures of interest for applications as scavenger.