Green synthesized nano-silver/cellulose aerogel as a robust active and recyclable catalyst towards nitrophenol hydrogenation

Abstract

Water contamination by hazardous aromatic nitro compounds is a serious problem, and reduction in p-nitrophenol (PNP) by combining a catalyst and a reductant has been a topic of intense interest in recent years. Although several methods have been explored for generating effective metal nanoparticle composites, the nano-size makes it challenging to recover after wastewater treatment, thus restricting its practical use. Additionally, the previously described approaches had critical disadvantages, including high material synthesis costs and secondary environmental contamination. Herein, nontoxic and low-cost materials were employed. A novel green technique for the synthesis of silver nanoparticles (AgNPs) decorated on 3D cellulose aerogel (CA) derived from water hyacinth was demonstrated using an aqueous extract ofJasminum subtriplinerve Blumeleaves as a stabilising and reducing agent for high-performance towards PNP reduction in the presence of NaBH4 in an aqueous medium. The as-prepared composites were investigated by powder X-ray diffraction, scanning electron microscopy with energy-dispersive spectroscopy, high-resolution transmission electron microscopy, Fourier transform infrared spectroscopy and Raman spectroscopy. Batch experiments of PNP hydrogenation were conducted to evaluate the catalytic performance. At room temperature, the reaction could be completed in about 10 min using the 1.5Ag/CA2.0 catalyst, with the catalytic activity almost unchanged. Moreover, the structure has no apparent deterioration after five cycles. Strikingly, the 26.15 nm-average size of AgNPs with even distribution on CA correlates with the good kinetic characterisation/feature (k = 0.34 min−1). In particular, the reduction rates of the three isomers of nitrophenol were examined and found to follow the following order: PNP > o-nitrophenol (ONP) > m-nitrophenol (MNP). This study provides some valuable insights into developing easily separated robust green catalysts for heterogeneous catalytic reactions in the environmental remediation field.