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.

Microplastics are the critical carriers of heavy metals in the environment. Thus, investigating the adsorption mechanisms between the microplastics and heavy metals is helpful to understand the migration and transformation pattern of the heavy metals in the environment. The adsorption of microplastics towards heavy metals can be largely affected by natural aging (e.g., UV-aging), environmental pH, and salinity. In this study, the adsorption of polystyrene (PS) towards Cu²⁺ and the effects of UV-aging, environment pH, and salinity on the adsorption were systematically investigated. The results show that the adsorption capacity of PS towards Cu²⁺ increased with the UV-aging time, as UV-aging increased the microcracks and oxygen-containing functional groups on the surface of the PS. Adsorption kinetics data followed the pseudo-second-order model, indicating that the interaction between PS and Cu²⁺ is chemical adsorption. Adsorption isotherms data could be well-described by both the Langmuir and Freundlich models, indicating that the adsorption was multilayer adsorption. As the solution pH and salinity can influence the surface charge of the PS, they could also affect the performance of the PS on Cu²⁺ adsorption. High pH facilitated the adsorption of PS towards Cu²⁺, while high salinity (above 1‰) inhibited the adsorption.