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Cellulose-based composites have aroused increasing interest as potential replacements for fossil fuel-based plastics. In this work, transparent cellulose-grafted-PLA nanocomposite films were prepared by grafting polylactide (PLA) onto cellulose. PLA was synthesized by in situ ring opening polymerization from a regenerated cellulose matrix, using zinc oxide nanoparticles (ZnONPs) in 1-ethyl-3-methylimidazolium acetate (EmimAc) as solvent. A facile route was devised to modify the starting material (cellulose paper) by partial dissolution and regeneration that used an ionic liquid (IL) as a smart nanowelding agent to assemble nanometric cellulose structures. The influence of the proportion of ZnONPs (1–5 wt%) and $$\textit{L}$$ L -lactide (LA) monomers (10–70 wt%) used on the properties of the resulting nanocomposite films was examined by comparison with an all-cellulose composite (ACC) and pure cellulose paper. Incorporating ZnONPs and PLA was found to enhance the mechanical, barrier and optical properties of the films. The maximum tensile strength and best barrier properties were those of a film obtained from 5%ZnONPs and 70%LA. FTIR spectra confirmed a new form of interaction between PLA and the regenerated cellulose matrix. Also, XRD spectra revealed a transition from cellulose I to II and an increase in the proportion of noncrystalline cellulose through partial dissolution and regeneration. Although the surface morphology of the nanocomposite films was influenced by the presence of ZnONPs and PLA chains, their color and chemical structure were not. The transparent cellulose-grafted-PLA nanocomposite films obtained are highly promising as packaging materials.

The global production of paper was more than 400 million tons in 2020, and about 40–50 kg of dry sludge/ton paper produced was generated. The management of this huge volume of solid waste material has become a serious problem for paper industry and an environmental challenge. Sustainable practices, alternative to disposal by landfilling, must be developed. The present work studied the potential of reusing sludge waste from paper manufacturer with the purpose to produce cellulose acetate films. Peer Reviewed Objectius de Desenvolupament Sostenible::9 - Indústria, Innovació i Infraestructura Objectius de Desenvolupament Sostenible::13 - Acció per al Clima Objectius de Desenvolupament Sostenible::12 - Producció i Consum Responsables

This work studies the suitability of bacterial cellulose (BC) matrices to prepare enzymatically active nanocomposites, in a framework of more environmentally friendly methodologies. After BC production and purification, two kind of matrices were obtained: BC in aqueous suspension and BC paper. A lipase was immobilised onto the BC matrices by physical adsorption, obtaining Lipase/BC nanocomposites. Neither morphology nor crystallinity, measured by scanning electron microscopy (SEM) and X-Ray diffractometry (XRD) respectively, of the BC were affected by the binding of the protein. The activity of Lipase/BC suspension and Lipase/BC paper was tested under different conditions, and the operational properties of the enzyme were evaluated. A shift towards higher temperatures, a broader pH activity range, and slight differences in the substrate preference were observed in the immobilised lipase, compared with the free enzyme. Specific activity was higher for Lipase/BC suspension (4.2 U/mg) than for Lipase/BC paper (1.7 U/mg) nanocomposites. However, Lipase/BC paper nanocomposites showed improved thermal stability, reusability, and durability. Enzyme immobilised onto BC paper retained 60% of its activity after 48 h at 60 ºC. It maintained 100% of the original activity after being recycled 10 times at pH 7 at 60 ºC and it remained active after being stored for more than a month at room temperature. The results suggested that lipase/BC nanocomposites are promising biomaterials for the development of green biotechnological devices with potential application in industrials bioprocesses of detergents and food industry and biomedicine. Lipase/BC paper nanocomposite might be a key component of bioactive paper for developing simple, handheld, and disposable devices.

In the present work, the laccase kinetics upon the oxidation process of phenolic compounds was studied using cyclic voltammetry (CV). Several hydroxybenzoic and cinnamic acid compounds were analyzed, and the oxidation kinetics were correlated to their chemical structures. Significant differences were observed, and several structural parameters were identified as enhancers of the reaction rate. Folin–Ciocalteau, ultraviolet–visible light (UV-vis) spectrophotometry, and thin-layer chromatography (TLC) methods were also used to assess the laccase-oxidation process. The TLC results correlated well with those from the CV, while the UV-vis results do so with those from the Folin–Ciocalteau analysis. Results suggest that intermediate adducts, nondetectable by CV, Folin–Ciocalteau, UV-vis, and TLC analyses, may be formed during the oxidation process. A new approach for using bare glassy carbon electrodes to detect phenolic compounds and monitor their oxidation using laccase enzymes is presented

In the first part of the present work, relevant findings concerning the laccase (Lacc) activation of alkyl gallates, and its implementation in developing hydrophobic properties on cellulose-based substrates are reported. Surface state energy by water contact angle (CA), absorption tests, and Cobb60 measurements were used to assess the hydrophobic behavior of treated substrates. SEM images of paper samples treated with functionalization solutions (FS) revealed the presence of lauryl gallate (LG, dodecyl 3,4,5,-trihydroxybenzoate) particles attached to fiber surfaces. Secondly, the chemical structure of the enzyme-oxidized LG and several gallates of variable chain length was elucidated by using Fourier transform infrared (FTIR) spectroscopy, and a plausible oxidation mechanism was developed. Based on them, the hydrocarbon chain of LG remains unaltered after enzyme oxidation, while the aromatic ring is significantly altered to form acidic adducts undergoing strong hydrogen bonding. Possible routes for the grafting of enzyme-modified LG to cellulose are proposed.