Dialysis-Driven Catalytic Process for the Simultaneous Reduction of Nitroaromatics and Separation of Aromatic Amines
Due to the extensive use, increased discharge into water, as well as toxic, mutagenic and cancerogenic character, aromatic nitro compounds (ANCs) are recognized as one of the most hazardous pollutants of anthropogenic origin. Fortunately, ANCs can be recognized as important substrates for the synthesis of aromatic amines (AAMs), that are the key building-blocks for the manufacturing of large-scale pharmaceuticals. In this context, the present study provides a new catalysis-dialysis process, that enables the simultaneous catalytic hydrogenation of ANCs and separation of resultant AAMs.
The catalysis-dialysis process was performed with the use of nanocomposite membranes (NCMs) loaded with Au nanoparticles (AuNPs). They were obtained by forming poly(vinyl chloride) films with the aid of cyclohexanone (CH) or tetrahydrofuran (THF), then the so-prepared films were functionalized with the selection of amines. Finally, the reduction-coupled adsorption of Au(III) allowed to fabricate and stabilize AuNPs within the membranes. The nanomaterials were analyzed using scanning transmission electron microscopy (STEM), and Fourier-transformation infrared spectroscopy (FT-IR). The catalytic reaction was carried out using UV-Vis spectrophotometryfor the model process where 4-nitrophenol (4-NP) is being reduced to 4-aminophenol (4-AP). A two-chamber dialysis unit was used for this purpose.
Results and Conclusion
NCMs with AuNPs allowed to effectively reduce 4-NP and to separate the resultant 4-AP. Each of the synthesized materials led to the 100% conversions of 4-NP. The 4-AP separation efficiency was linked with the greater in the case of membranes obtained in the presence of THF. This suggests the NCMs were efficient catalysts, that separation properties were linked with the diffusion channels present in the materials. The outcome of the research suggests, that the novel catalysis-dialysis process could be a tempting alternative towards traditional hydrogenation reaction, as the applied NCMs offer an additional functionality, enabling the production of AAMs from waste sources.
Keywords – Nanoparticles, Nanocomposite, Membranes, Catalyst, Nitroaromatics.