Insight into surface and structural changes of montmorillonite and organomontmorillonites loaded with Ag

Abstract

A raw montmorillonite (MMT) and three organomontmorillonites (OMMTs) with different amounts of hexadecyltrimethylammonium bromide (HDTMABr), and further silver loading (MMT–Ag or OMMT–Ag) were used to study their surface and structural changes and fungicidal activity. For OMMT and OMMT–Ag samples, the specific surface area and micropore amount decreased with the increase in surfactant loading, whereas textural properties remained constant. Surfactant entrance into the interlayer with the increase in surfactant loading was irrespective of Ag loading, whereas a decreasing number of stacked clay platelets and loss of surfactant were found after Ag incorporation. Ag nanoparticles of different sizes and large silver aggregates found in OMMT–Ag altered the electric surface charge as compared with the OMMT samples. Although the surfactant loading up to actual 100% of the MMT cation exchange capacity decreased silver retention, for MH2–Ag sample (with 200% HDTMA loaded with respect to the MMT's cation exchange capacity, and further Ag loading) silver retention was close to that of MMT and null silver lixiviation could be assigned to the HDTMA–Ag complex and AgBr formation. Fungicidal activity was correlated with surfactant loading, increasing with Ag addition.