Bacterial cellulose (BC) is an eco-friendly biopolymer with outstanding structural and functional properties, offering promising applications in sustainable packaging and bio-based materials. In this study, we demonstrate the feasibility of producing BC via spontaneous fermentation, using grape pomace supplemented with sucrose as the sole carbon source, nutrient substrate, and microbial inoculum, without the addition of commercial strains or nitrogen supplements. Fermentation was conducted under static conditions, yielding biofilms with stable structural characteristics and BC production of up to 14.1 g/L, thereby confirming the efficiency of this low-cost, residue-based process. The films obtained exhibited well-organized polymeric networks, with thermal stability in the range of T_g ≈ 159–266 °C and mechanical resistance comparable to or higher than conventional biopolymers. Characterization confirmed reproducible chemical profiles, thermal stability, and measurable variation in mechanical performance, with a tensile strength ranging from 0.0001 to 105 MPa and an elongation at break of 15±5%. The process highlights a resource-efficient and sustainable pathway, adaptable to rural contexts and aligned with circular economic principles. While minor variations among replicates reflected the intrinsic variability of biological systems, mean values and standard deviations demonstrated reproducible physicochemical and mechanical properties. These findings demonstrate that BC derived from agro-industrial residues can be produced under simple, low-input conditions, opening opportunities for scalable valorization in functional and sustainable materials.

In this study, magnetic core-shell Fe₃O₄@ZIF-8 was synthesized via a hydrothermal method and applied to Polyethylene terephthalate(PET) degradation. The catalytic degradation of PET by Fe₃O₄@ZIF-8 was carried out under atmospheric pressure, yielding high-value bis(2-hydroxyethyl) terephthalate (BHET) monomers. The as-synthesized Fe₃O₄@ZIF-8 core-shell composites possess hierarchical porosity with tunable nanoscale cavities. SEM and TEM analyses confirmed the core-shell morphology, with nanoparticles having a size distribution of 180–280 nm. The degradation product was identified as a high-purity, colorless, and transparent monomeric BHET through ¹H NMR and LC analyses. Based on a series of onefactor experiments and a Box-Behnken experimental design, the optimal process conditions were determined to be an alcoholysis temperature of 200°C, a catalyst dosage of 0.5 wt% (relative to PET mass), a reaction time of 50 min, and an ethylene glycol-to-PET mass ratio of 4.5:1. Under these conditions, the actual BHET yield reached 81.12%, closely matching the predicted value.