Although recent work has shown natural lignin products are promising to fabricate various polymer based functional composites, high-value applications were challenged by their structural complexity and inhomogeneity. This work specially assessed the potential of four technical lignins for cellulose based functional films production. These four technical lignins were obtained by emerging pretreatment systems, i.e., lactic acid-betaine deep eutectic solvent (DES), ethanol organosolv, soda/anthraquinone (Soda/AQ) and the sodium salicylate hydrotrope, and their phenolic substructures were comparatively identified by prevalent 31P NMR technique. The influence of lignin chemical structure on the antioxidant potential and UV-shielding performance of the prepared cellulose/technical lignin composite films were assessed. Results showed severe organosolv and soda/AQ pretreatment produced technical lignins with higher total phenolic hydroxyl groups (3.37 and 3.23 mmol g-1 respectively), which also exhibited higher antioxidant activities. The composite films could effectively block the ultraviolet lights especially for UVB region (ultraviolet B, 280–315 nm) at only 5 wt.% lignin content. The contribution of lignin phenolic substructures to both antioxidant activity and UV-shielding property from high to low was syringyl > guaiacyl > p-hydroxyphenyl phenolic hydroxyl groups. This work provided some useful information that could facilitate upstream lignin extraction or downstream value-added applications.

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Proper disposal of large-quantity waste cigarette butts (WCBs) is of great importance for alleviating marine and land pollution, but it has been challenged by their complex compositions and toxic compounds contents. This work showed a technically feasible way to valorize WCBs through bioethanol production with high titers. Three deacetylation solvent systems, i.e., aqueous alkali, emerging alkali ethanol organosolv, and alkali deep eutectic solvent, were assessed for their abilities to produce high-purity and digestible cellulose. Results showed the acetyl groups content in WCBs after various deacetylation processes was significantly decreased from 46.65% to ∼4.66%, corresponding to the cellulose content increasing from 54.94% to ∼94.61%. It was proposed that the dual function of acetyl groups removal and cellulose deconstruction of these deacetylation solvent systems was responsible for enriching cellulose and enhancing its enzymatic accessibility, which allowed the subsequent facile simultaneous saccharification and fermentation (SSF) process to be operated at 20% (w/v) high solids loading. When the overall mass balance was traced during the deacetylation and SSF process based on 100 g of WCBs, a maximum bioethanol production of 25.4 g with a high titer of 76.5 g L −1 could be obtained. This work showed that a facile deacetylation process using alkaline solvent systems was promising for clean recycling of WCBs and also could provide useful technological information for valorizing other waste cellulose ester plastics.

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