LAUSR

'BACKGROUND' Deinking is an important part of paper recycling which 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 the presented research five different alternative fibre materials from different agro residues and industrial processes were used for the pilot production of papers. Papers containing fibres from invasive plants (Japanese knotweed), dedicated crops (Miscanthus, Acacia), agro residues (Tomato stems) and industrial waste (Jute - fibres from coffee bags) have been 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' The enzymatic treatment improved the mechanical properties of the deinked pulp in comparison with the classic chemical treatment. Mechanical strength for almost all papers slightly increased (the breaking length up to 20% (Tomato and Jute), while the optical result (brightness) increased similarly for both processes due to the bleaching action of the colour shaded samples, while 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 the combination of adjusted enzymatic treatment as a precursor for the deinking of the paper-based packaging materials sourced from alternative fibres showed promising results regarding mechanical properties, while 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. This article is protected by copyright. All rights reserved.