UV-shielding alginate films crosslinked with Fe³⁺ containing EDTA

In this study, we fabricated a soft, transparent UV-shielding film (Alg-Fe³⁺-EDTA) by crosslinking sodium alginate with a ferric ion solution containing EDTA. The obtained films were characterized via SEM, ATR-FTIR, XRD, TG and DTG; the results indicated that the synergistic gelation of ferric alginate and alginic acid existed in Alg-Fe³⁺-EDTA film. The Alg-Fe³⁺-EDTA film performance to be optimized under the following conditions: 1.6% Fe³⁺, 0.8% EDTA, and crosslinking duration of 12 min. The Alg-Fe³⁺-EDTA film had high visible light transmittance, the UV-C (200-280 nm) and UV-B (280-315 nm) shielding rates were 100%, and the UV-A (315-400 nm) shielding rate was 98.37%; the UPF reached 50+; additionally, the tensile strength and elongation-at-break were 56.85 MPa and 10.45%, respectively, and still have ultraviolet shielding effect under water environments or after strong light irradiation. This work provides an efficient method to improve the optical and mechanical ability of ferric alginate films.