One-step synthesis of ultra-small silver nanoparticles-loaded triple-helix ?-glucan nanocomposite for highly catalytic hydrogenation of 4-nitrophe-nol and dyes

Finding an eco-friendly homogeneous catalyst with high efficiency to rapidly clean up dyes and 4-nitrophenol in wastewater is urgently to be solved. Herein, we ingeniously designed a stable and reusable homogeneous catalyst of ultra-small silver nanoparticles (AgNPs)-loaded triple-helix beta-glucan (BFP) nanomaterial (BFP-Ag) via one-step reduction in dimethyl sulfoxide with BFP as the reductant. Moreover, BFP triplex formed nanotubes, acting as a matrix to disperse and stabilize AgNPs through Ag-O bonds in water. The ultra-small AgNPs (2.8-10 nm) were embedded into the hollow cavity of BFP nanotubes indicated by the aqueous solution color. BFP-Ag effectively catalyzed reduction of 4-nitrophenol with the higher catalytic efficiency for smaller size of AgNPs. The catalytic turnover frequencies of BFP-Ag nanocomposite for reduction of Congo Red, Methyl Orange, Rhodamine B and 4nitrophenol were determined to be 1423.02 h-1, 349.52 h-1, 452.78 h-1 and 1335.89 h-1, respectively, which were far higher than those of the most reported catalysts. BFP-Ag maintained over 95% conversion after eight continuous cycles and the entire catalytic and recovery process could be achieved by a simple filter device for the practice applications. The hot filtration and recovery test verified the homogeneity and stability of BFP-Ag. This work provides a novel strategy for designing eco-friendly homogeneous catalysts in wastewater treatment and expands the application of natural polysaccharides in the synthetic catalysis.