Alginate and polyethyleneimine dually mediated synthesis of nanosilver-containing composites for efficient p-nitrophenol reduction

Three-dimensional silver/polyethyleneimine/alginate hydrogel beads have been prepared successfully via a facile and simple one-pot assembly method, which can be used efficiently in catalytic hydrogenation reaction of p-nitrophenol under batch and fixed-bed experiment. Polyethyleneimine is used to reduce and limit the growth of nano-silver particle and alginate microsphere is used as the catalyst carrier, leading to form well silver nanoparticles dispersion. Several characterizations were applied to the materials, such as X-ray diffraction, scanning electron microscopy, transmission electron microscopy and X-ray photoelectron spectroscopy. As-prepared catalysts only spent 120 s finishing reaction at ambient temperature (20% silver load) and stable catalytic performance with high conversion percentage for p-nitrophenol about 90% at 298 K under fixed-bed condition. The relationship between concentration and time was well depicted by Pseudo-first order kinetic model. The catalytic performance for recycled catalyst remained highly efficient, and the conversion efficiency of 96.4% can be maintained after 10 cycles.