Polymeric Nanocatalysts with Rhenium Nanostructures for Hydrogenation of Nitroaromatic Compounds in Wastewaters
Nitro-substituted aromatic hydrocarbons (NARs) are indispensable in the manufacturing of a number of products that are considered as important achievements of the modern technology. However, NARs reveal genotoxic properties, and as such they have been identified as one of the major chemicals posing the risk of lungs, bladder, pancreas and in case of children also urinary track, and neurological-related cancers. In this context, there is a strong incentive for developing stable and efficient heterogenous nanocatalysts for the reduction of NARs.
In this work, newpolymeric nanocomposites (pNCs) containing rhenium nanostructures (ReNSs)are proposed. It is hypothesized, that these unique materials will facilitate the catalytic decomposition of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) due to the ReNSs immersed within them. The synthesis of pNCs with ReNSswas carried out using reduction-coupled adsorption of ReO4- on amino functionalities on anion exchange resin derived from 1-(2-hydroxyethyl)piperazine, 1,4-bis(3-aminopropyl)piperazine, and 1,1’-Carbonyldiimidazole. The resultant nanomaterials were analyzed using spectroscopic as well as microscopic methods, while the catalytic activity thereof was estimated by monitoring a progress of the 4-NP to 4-AP reduction using UV-Vis spectroscopy.
Amino functionalities played a primary role in the ReO4-reduction, allowing to obtain pNCs with ~10% content of ReNSs. Based on the acquired Energy-dispersive X-Ray spectra, the obtained and loaded ReNSs were Re0that size ranged from 10-150 nm.The so-prepared catalysts led to the 90% conversion of 4-NP with a maximum rate constant of 0.28 min-1 over 11 subsequent catalytic cycles.
Based on the results, it can be concluded that the applied methodology indeed led to the synthesis of pNCs with ReNSs. The yields of 4-NP conversions, linked with catalysts stability suggest that the obtained nanomaterials can be considered as prospective and efficient nanocatalysts enabling controllong hazards assotiated with the occurrence of NARs in the environment
Keywords - Rhenium; Nanoparticles; Nanocomposite; Catalyst; Nitroaromatics.