High-capacity adsorption of organic dyes using separable pullulan gel encapsulated with PDA-modified ZIF-8.

In this investigation, a hydrogel adsorbent featuring remarkable efficiency in dye adsorption was successfully synthesized by the integration of natural polysaccharide (pullulan) and nanoparticles (ZIF-8@PDA). The prepared natural polysaccharide nanocomposite hydrogels not only exhibit superior mechanical strength and biocompatibility, but also demonstrate adeptness in the removal of dye pollutants. The dye removal capacities were 615.4 mg/g for malachite green (MG) and 525.8 mg/g for Congo red (CR), respectively. Notably, the adsorption process exhibits minimal susceptibility to variations in water quality and the presence of co-existing ions. The pH-responsive surface charge conversion capability of the adsorbent renders it recyclable, maintaining a dye adsorption performance exceeding 88 % even after 5 cycles of repeated usage. Overall, these environmentally friendly natural polysaccharide nanocomposite hydrogels hold potential for addressing complex wastewater treatment challenges and long-term use.