One-Step Tannic Acid/Iron (II) Treatment for Enhanced Silk Fabric Performance

The modification of silk fabric by complexation of tannic acid with ferrous ions (TA-Fe²⁺) and its properties were studied in this paper. The one-step process of silk fabric was optimized. The formation mechanism of tannic acid/Fe(II) complexation products and the properties and functional indexes of modified silk fabric were analyzed by particle size, ultraviolet–visible absorption spectrum (UV–Vis), Fourier infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), thermogravimetric analysis (TG) and X-ray diffraction (XRD). Concurrently, the antibacterial, antioxidant, UV-resistant, and stain-resistant properties of the one-step modified silk fabric were tested. The results of microscope, SEM, XPS, and EDS showed a single ligand 1:1 complex of TA-Fe²⁺ that was formed and attached to the structure of silk fibers under the condition of pH 3, and the water-soluble components of the product penetrated into the cross-section of the silk fibers. The XRD analysis indicates that the crystallinity of the modified silk fabric has been improved, as evidenced by sharper and more pronounced diffraction peaks. The modified silk fabric exhibited a UPF value of 30.58, indicating a high level of UV protection, as fabrics with UPF values over 30 are recognized for their effectiveness in blocking UV rays. Additionally, with an ABTS^˙+ clearance rate of 87.36%, the fabric demonstrates excellent antioxidant properties. The fiber was tested against E. coli and S. aureus following GB/T 20944.3–2008, with results indicating that the antibacterial rate of Staphylococcus aureus was more than 90%. The contact angle of the modified silk fabric is 138^°, which has certain water-repellent and stain-resistant properties.

Graphical Abstract