CONICET | Buscador de Institutos y Recursos Humanos

A large family of azo dyes have been developed and used in the textile industry, including for leather tainting, and are therefore expected to exhibit strong interactions with collagen-based materials. Here we investigate the mechanisms of adsorption of the Remazol black B dye ontype I collagen hydrogel. Higher and stronger retention of the dye is achieved in alkaline conditions, correlated with enhanced thermal and mechanical stability of the hydrogel. The formation of a covalent bond between the dye and the protein network via Michaels reaction is suggested and supported by the detailed analysis of the kinetics and thermodynamics of the sorption reaction. Sorption capacity of collagen hydrogel at pH 9.00 was ca. 1 mmol.g-1 (i.e. 1 g.g-1). Even in acidic conditions that are closer to natural waters, the capacity was > 0.5 g.g-1, larger than reported values for activated carbon. The adsorption process is fast, the adsorbent (collagen) is biodegradable, and azo dyes don´t suffer rupture that could origin products even more toxic than the dye without degradation. The interaction between collagen and dye is chemically-stable limiting the risk of secondary contamination due to dye leaching from the sorbent. Another advantage of such hydrogels is their ability to reduce the generation of waste thanks to their strong reduction in weight and volume upon drying that should reduce the needed storage area leading also to costs reduction. Their application in water remediation would also constitute a new valorization route forindustrial processes producing collagen as waste. Type I collagen hydrogels combine low cost, fast sorption, high loading and strong retention capacity together with low storage volume, making thempromising materials for dye remediation. Dye-modified hydrogels may also find applications in the biomedical field.