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BACKGROUND: Deinking is an important part of paper recycling that involves the removal of ink particles from the paper fibres. This industrial process is important so that the fibres can be recirculated back into paper production, which enables better sustainability as fewer fresh fibres are needed. In this study, we examined five different alternative fibre materials from different agricultural residues and industrial processes for the pilot production of papers. Papers containing fibres from invasive plants (Japanese knotweed), dedicated crops (miscanthus, acacia), agricultural residues (tomato stems), and industrial waste (jute - fibres from coffee bags) were printed with water-based flexo inks and deinked with two separate processes (chemical and enzymes). Mechanical (break and tensile index, breaking length) and optical properties (ISO whiteness, brightness and CIE L*a*b* values) were measured and ink elimination IR700 and deinking efficiency was calculated for the two deinking processes. RESULTS: Enzymatic treatment improved the mechanical properties of deinked pulp in comparison with the classic chemical treatment. Mechanical strength for almost all papers increased slightly (breaking length up to 20% in tomato and jute), and the optical result (brightness) increased similarly for both processes due to the bleaching action of the colour-shaded samples, whereas the deinking efficiency showed mixed results between chemical- and enzyme-type deinking (with chemical achieving better elimination measured at 700 nm) in the typical range of ink elimination values (15-35%) for flexographic inks. This indicates further optimization of the deinking with enzymes is needed due to different alternative fibre compositions and variations of residues in the delignification processes. CONCLUSION: Using a combination of adjusted enzymatic treatment as a precursor for deinking of paper-based packaging materials sourced from alternative fibres showed promising results regarding mechanical properties, whereas the optical properties need to be improved with cellulase optimization or by using mixes of different enzymes. These kinds of paper materials printed with flexo inks were found to be successfully deinkable with the chemical ISO-based deinking protocol. [ABSTRACT FROM AUTHOR]

BACKGROUND: The usage of natural polysaccharides is attractive to researchers around the world. At the same time, non‐/low‐toxic crosslinkers prepared by polysaccharides are expected to fabricate protein‐based films in many fields. Herein, different dialdehyde polysaccharides (DPs) were successfully synthesized and applied to prepare gliadin‐films under alkaline conditions. The functional properties and formation mechanisms of the films were fully investigated. RESULTS: The results showed that the mechanical properties, water‐resistant properties, thermal stability, and antibacterial properties of the gliadin‐films were improved by DPs and alkali treatment. Particularly dialdehyde dextrin (DAD) crosslinked gliadin‐films showed the highest tensile strength, but no additional effect on their elongation, or advancement on the other functional properties. The film‐forming mechanisms indicated that Schiff base bonds, hydrophobic interactions, electrostatic interactions, and hydrogen bonds were the main forces in the films, supporting their improvement in functional properties. CONCLUSION: DPs, especially DAD, can be a promising crosslinker in fabricating gliadin‐films. These findings have shown great promise to seek an effective crosslinker for fabricating gliadin/protein‐based packaging. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]