Palladium nanoparticles embedded over chitosan/γMnO2 composite hybrid microspheres as heterogeneous nanocatalyst for effective reduction of nitroarenes and organic dyes in water

Abstract

Effective remediation of toxic organic pollutants such as nitroarenes and dyes from water systems is an important global issue for purification of drinking water or wastewater. Therefore, the development of effective strategies to treat these pollutants has recently become a critical and fundamental issue, and one of the most useful methodologies is to utilize heterogeneous catalysts. In this regard, a novel nano-sized heterogeneous catalyst system was designed in the present study by stabilizing palladium nanoparticles on the composite hybrid microspheres based on chitosan and γMnO2 which was developed as the stabilizer (Pd/CS/γMnO2). The morphological/structural characterization of Pd/CS/γMnO2 nanocatalyst was carried out by SEM, XRD, TEM, BET, EDS, FT-IR, and TG analyses. Then, the catalytic role of Pd/CS/γMnO2 nanocatalyst was evaluated towards catalytic reduction of some environmental pollutants such as 2-nitroaniline (2-NA), 4-nitrophenol (4-NP), 4-nitroaniline (4-NA), 4-nitro-o-phenylenediamine (4-NPD), congo red (CR), methylene blue (MB), methyl orange (MO), methyl red (MR), and rhodamine B (RhB) in water by using NaBH4 at room temperature. The tests showed that Pd/CS/MnO2 effectively and rapidly catalyzed the reduction of these pollutants and could be reused up to 8 cycles. Additionally, it was found that the catalytic activity of Pd/CS/γMnO2 nanocatalyst was superior to those of many catalysts against the same reduction reactions. This paper concludes that Pd/CS/γMnO2 nanocatalyst appears to have a high potential to serve as an effective catalyst for remediation of wastewater thanks to its facile preparation, low cost, and good catalytic activity.