Preparation and assessment of antimicrobial properties of bimetallic materials based on NaY zeolite

Abstract

ZnAg–Y was the most active material tested against the bacteria Escherichia coli and the yeast Saccharomyces cerevisiae as indicator strains.

Mono and bimetallic NaY catalysts with high performance in nitrate reduction in water

“…The presence of hydroxyl groups from the characteristic faujasite cavities and physisorbed water are identified by the (O-H) stretching vibration in the range of 3600-3100 cm À1 and the (O-H) deformation band at 1635 cm À1 . The bands corresponding to the lattice vibrations are observed in the spectral region between 1300 and 450 cm À1 [21][22][23]. These principal zeolite vibrational bands are not shifted or broadening after the metal incorporation, further substantiating the proposal that the zeolite framework remains unchanged after the treatments.…”

“…The data does not reveal any significant zeolite structural change during the metal exchange. All FTIR spectra of the mono and bimetallic catalysts (data not shown) are dominated by the strong bands assigned to the vibrational modes arising from the zeolite structure and are very similar to the parent NaY zeolite [21][22][23]. The presence of hydroxyl groups from the characteristic faujasite cavities and physisorbed water are identified by the (O-H) stretching vibration in the range of 3600-3100 cm À1 and the (O-H) deformation band at 1635 cm À1 .…”

“…The analysis of the patterns indicates that some cation redistribution occurred following the ion-exchange treatment [22]. The standard method ASTM D-3906-80 was used for estimating the relative crystallinity of catalysts by comparing the peak intensities of the samples with NaY used as a standard sample (100% crystalline).…”

“…The pH pzc value obtained for the parent NaY zeolite was 7.1. The preparation of these catalysts was performed in the liquid phase using different aqueous solutions of metal nitrate by the ion exchange method [22] at room temperature and can be schematically represented for monometallic by Eq. (1) …”

“…Before applying the ion exchange method, the parent zeolite was submitted to a thermal treatment at 120°C for 12 h in an oven. The monometallic (Cu-Y and Pd-Y) and bimetallic (PdCu-Y and CuPd-Y) catalysts were prepared by the ion exchange method according to a previously published procedure [22]. Two monometallic catalysts were prepared by exchanging 5 g of NaY zeolite with 50 mL of 0.01 M solutions of the appropriate metal nitrate (Cu(NO 3 ) 2 or Pd(NO 3 ) 2 ) in an Erlenmeyer flask with stirring, at room temperature, during 24 h. The bimetallic catalysts, PdCu-Y and CuPd-Y were prepared by the introduction of the second metal by ion-exchange with 0.01 M of these metal solutions into Cu-Y or Pd-Y.…”