Ag2CO3 phases in nanocomposites with palygorskite and their effects on photocatalytic and antibacterial activities

Abstract

Various nanocomposites based on Ag2CO3 loaded onto natural fibrous palygorskite (Pal) were elaborated by a simple precipitation route. Their composition ranged from metastable hexagonal β-Ag2CO3 nanoparticles immobilized on the surface of Pal microfibers to a mixture with stable monoclinic m-Ag2CO3 particles trapped in the tangle of Pal fibers. The choice of elaboration parameters enables to control the relative content of each phases phase ratio “metastable β-hexagonal / (stable monoclinic + metastable β-hexagonal)” of Ag2CO3 and thus to tune the resulting multifunctional properties (mainly photocatalytic and biocidal activities) of the nanocomposites.Optical studies interestingly revealed, for all Ag2CO3-Pal nanocomposites, a noticeable absorption in the visible light range. Accordingly, all the Ag2CO3 based Pal nanocomposites were found to be photoactive under visible light for the removal of Orange G (OG) dye but biphasic (β + m)-Ag2CO3-Pal nanocomposite was more photoactive than those in which Ag2CO3 was monophasic (either β-hexagonal or monoclinic phases). This could be due to synergy effects between the two Ag2CO3 phases. Besides, all the developed Pal based nanocomposites remained active upon several reusability cycling tests. Likewise, both the nanocomposites materials and the starting Pal clay mineral were found antibacterial against gram-positive (Staphylococcus aureus) and gram-negative (Escherichia coli) bacteria.