# From Waste to Function: Valorization of Collagen-Based Wastes with Natural Deep Eutectic Solvents for Bioadhesive Applications

## TL;DR

This paper presents a sustainable method to convert leather waste into bioadhesives using natural solvents, which are effective on wood and resistant to water.

## Contribution

A novel green method for valorizing leather waste into functional bioadhesives using natural deep eutectic solvents is introduced.

## Key findings

- Bioadhesives made from treated leather scraps showed excellent binding performance, especially on wood substrates.
- Collagen structural and thermal changes were analyzed using advanced techniques like ATR-FTIR and TGA.
- The method aligns with circular economy goals by upcycling industrial waste into high-performance materials.

## Abstract

In this study, we propose a novel, environmentally, economically,
and energetically sustainable approach for the valorization of vegetable-tanned
leather waste, aiming at producing biobased adhesives with antibacterial
properties and promising water resistance. The treatment of leather
scraps was carried out using various Natural Deep Eutectic Solvents
(NADES) in mild conditions (1 h, 60 °C), i.e., lactic acid:urea
in a molar ratio of 2:1, choline chloride:lactic acid in a molar ratio
of 1:1, and choline chloride dehydrated oxalic acid in a molar ratio
of 1:1. The resulting bioadhesives exhibited excellent binding performances,
in particular, on wood substrates. Structural modifications and its
thermal behavior of collagen after the treatment were investigated
using Fourier Transform Infrared Spectroscopy with Attenuated Total
Reflectance (ATR-FTIR), Thermogravimetric Analysis (TGA and TGA/FTIR),
Evolved Gas Analysis–Mass Spectrometry (EGA-MS), Pyrolysis–Gas
Chromatography–Mass Spectrometry (Py-GC-MS), and proteomic
techniques. Overall, this approach highlights a circular and green
strategy for upcycling leather industry byproducts into high-performance
materials, aligning with current goals in waste minimization and resource
efficiency.