Silk Sericin-Polyethyleneimine Hybrid Hydrogel with Excellent Structural Stability for Cr(VI) Removal

In this study, a hydrogel-type high-performance Cr(VI) adsorbent was prepared using silk sericin (SS), a secondary silkworm silk protein. Cationic polyethyleneimine (PEI) was used during gelation to confer structural stability to SS and improve its Cr(VI) adsorption performance. The compressive test results indicated that the compression deformation stability of the SS-PEI hybrid hydrogel was four times higher than that of the pristine SS hydrogel owing to the synergistic effect of electrostatic attraction and chemical crosslinking. In addition, the SS-PEI hydrogel presented an excellent Cr(VI) removal capacity of 466 mg/g, which was the highest value among all the SS-based adsorption materials reported to date. In addition, SS-PEI maintained an excellent adsorption efficiency of 90.3% after six adsorption cycles.