环境材料与生态化学研究发展中心知识库

A granular hydrogel based on chitosan (CTS) and acrylic acid (AA) was prepared using Fenton’s reagent as the redox initiator and N,N′-methylenebisacrylamide as the crosslinker under ambient conditions. The resulting three-dimensional (3D) networks can serve as micro- or nano-reactors for the production of highly stable silver nanoparticles by the in situ reduction of silver nitrate (AgNO₃) with sodium borohydride (NaBH₄) as reducing agent and Al³⁺ as surface crosslinking agent. The as-prepared Ag-entrapped hydrogel was successfully confirmed by means of Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and thermogravimetric analysis (TGA), and then tested to catalyze the NaBH₄ reduction of two organic dyes: methylene blue (MB) and Congo red (CR). The catalytic results indicate that within 30 min, MB and CR with an initial concentration of 20 mg L⁻¹ can be reduced completely, and the catalytic activity is independent of initial pH and ion strength. In addition, the Ag-entrapped hydrogel shows excellent reusability for ten successive cycles, with no appreciable decrease in the catalytic effects.