Oxidation catalysts prepared from biosorbents supported on zeolites

Abstract

The catalytic oxidation of 1,2-dichlorobenzene was investigated over NaYand NaX zeolites, loaded with chromium through the action of a robust biosorption system consisting of a bacterial biofilm supported on the zeolites. The results of biosorption showed that the maximum metal removal efficiency was 20%, in both systems based on NaYor NaX, starting from solutions with chromium(VI) concentrations ranging from 50 to 250 mg Cr /L. The bacterial biofilm, Arthrobacter viscosus, supported on the zeolite reduces Cr(VI) to Cr(III). The Cr(III) is retained in the zeolite by ion exchange. The new catalysts were characterized by spectroscopic methods (FTIR ), chemical analyses (ICP-AES), surface analysis (XRD) and thermal analysis (TGA). The various techniques of characterization show that this biosorption process does not modify the morphology and structure of the FAUzeolites. These catalysts, Cr/FAU, prepared through this new procedure present good activity and selectivity for dichlorobenzene oxidation in wet air at 350 8C. The Cr 50 -Y was selected as the most active, selective and stable catalyst for oxidation of 1,2-dichlorobenzene in wet air. #

Removal of Cr(VI) from Aqueous Solutions by a Bacterial Biofilm Supported on Zeolite: Optimisation of the Operational Conditions and Scale‐Up of the Bioreactor

“…The reaction with diphenylcarbazide is nearly specific to Cr. [24]. These authors reported that a biofilm of A. viscosus supported on Y and X zeolites was able to remove chromium from dilute solutions (50-250 mg Cr(VI) per litre) with a maximum removal efficiency of 20 %.…”

“…Figueiredo et al [24] reported an innovative process that combines the use of a zeolite and an A. viscosus biofilm to remove Cr(VI) in solution. They found that the A. viscosus bacteria supported on the zeolite reduce Cr(VI) to Cr(III), and the Cr(III) is retained in the zeolite by ion exchange.…”

“…This study focuses on the scale-up of a new technology developed by Figueiredo et al [24] to remove low concentrations of heavy metals from industrial effluents. To complete the previous study, the bioreduction of Cr(VI) to Cr(III) using A. viscosus combined with the Cr(III) removal using a specific zeolite was conducted in bioreactors.…”

Enzymatic mechanism and biochemistry for cyanide degradation: A review

“…In addition some microbe uses metal-cyano complexes as nitrogen source and for the dissociation of these complexes they form biofilm on the surface to adsorb metal ions or form siderophores. Siderophores are the iron sequestering compounds produced by microbes for iron chelating [37][38][39].…”

Polyacrylamide–clinoptilolite/Y-zeolite composites: Characterization and adsorptive features for terbium

“…Clinoptilolite was characterized with the diffractions appeared at 9. Y-zeolite was a faujasite type mineral defined by the reflections at 6.3, 10.3 and 12.1 (2Â • ) [5,21,22,48,49]. Bare minerals and the composites had similar XRD patterns; there were not any distortions and shifts in any of the peaks, which predicated that the minerals were not deformed with inclusion of the hydrogel.…”