Bio-Sponge With Collagen Fibrils as Building Blocks to Effectively Remove Anionic Dyes From Aqueous Solution

The cross-linked collagen sponge (CCS) was fabricated by crosslinking mesoscopic collagen fibrils using glutaraldehyde as a crosslinking agent. The structure of CCS was analyzed using scanning electron microscopy (SEM), Fourier infrared spectroscopy (FTIR), and thermal analysis (TA). Static adsorption experiments were conducted with Congo red (CR) as an anionic dye model to assess the adsorption capability. The findings indicate that the adsorption behavior of CCS follows the Langmuir isothermal adsorption model, quasi-second-order kinetic model, and molecular diffusion model. At 333 K, CCS demonstrates a remarkable maximum adsorption capacity ( Q max ) of 232.1 mg/g, surpassing other reported bio-based materials in terms of its exceptional performance as an adsorbent. Thermodynamic analysis confirms the spontaneous uptake of CR by CCS. Additionally, repeated tests involving both adsorption and desorption validate the outstanding stability and reusability of CCS for sorption of anionic dyes.