Synthesis and application of silver nanoparticles loaded on modified montorillonite

Na⁺montmorillonite (MMT) was modified with L-cystine, polyvinylpyrrolidone or mercaptoacetic acid and then silver (Ag) was loaded on the modified MMTs via ion-exchange reaction under microwave irradiation for 4 min, and finally the Ag ions were turned to Ag nanoparticles (Ag NPs) under the irradiation of an ultraviolet lamp. The Ag-loaded L-cystine-modified MMT (Ag@AA-MMT) with an Ag content of 10.93 wt% was the highest of all, suggesting the distinct advantage of microwave-assisted ion-exchange reaction on a modified MMT. X-ray photoelectron spectroscopy confirmed the successful loading of silver and the strong interaction between sulphur and Ag. Scanning electron microscopy, transmission electron microscopy and high-resolution transmission electron microscopy and X-ray diffraction patterns proved the existence and formation mechanism of metallic Ag NPs. The Ag-loaded modified MMT has shown a slow release property and good thermal stability owing to the shielding effect of the MMT layers. The Ag@AA-MMT, showing a very excellent antibacterial property and catalytic activity, exhibited a wide range of potential applications.