Green synthesis of polysaccharide-based Ag@AgCl photoactive porous hydrogel spheres for enhanced visible light photocatalytic degradation of organic pollutants.

Improving the visible light activity and recyclability of photocatalysts remains a key challenge for organic pollutant degradation in wastewater. In this study, enteromorpha polysaccharide (EP) and xanthan gum (XG) were combined to preload Ag ions, with CO bubbles introduced via a pressure-decompression method. After cross-linking with ZrOCl via drip infusion, porous hydrogel spheres embedded with photoactive Ag@AgCl nanoparticles (NPs) were obtained. The porous spheres were characterized using SEM, TEM, FT-IR, XRD, XPS, and EIS. The results revealed that the formation of hierarchical pore structure by CO bubbles and variations in EP content affected the distribution of Ag@AgCl NPs, leading to differences in photoelectric efficiency. Under optimal conditions, Ag@AgCl NPs with an average size of 100 nm were uniformly distributed throughout the interior and exterior of the porous sphere, exhibiting excellent photocatalytic efficiencies and the degradation rate constants for rhodamine B (RhB), methyl orange (MO), tetracycline (TC), and norfloxacin (NOF) were 0.22, 0.28, 0.013, and 0.025 min, respectively. Photocatalytic cycle tests showed the good recyclability of the hydrogel spheres, and the photocatalytic mechanisms were also revealed. Moreover, good biocompatibility of the hydrogel was confirmed by cytotoxicity tests. This research provides valuable references for developing green and efficient polysaccharide-based photocatalytic materials.