The contamination of water resources by heavy metals poses a serious environmental risk, and conventional treatment methods face significant limitations. This review addresses the issue by presenting a critical analysis of the development of sustainable biosorbent and biopolymeric materials for heavy metal adsorption, highlighting advances, challenges, and future perspectives. To this end, a systematic bibliometric analysis of 120 documents was conducted, extracted from the Scopus and Web of Science databases, covering the period from 2003 to 2025. The results indicate exponential growth in scientific interest in biopolymers such as cellulose, chitosan, lignin, and alginate, especially in the form of aerogels, which demonstrate high adsorptive capacity through mechanisms such as complexation, chelation, and ion exchange. The analysis also reveals the main factors influencing process efficiency, such as pH, temperature, and contact time. It is concluded that, although these sustainable materials are highly promising, challenges related to scalability, selectivity in complex effluents, and regenerability still need to be overcome to enable their large-scale industrial application, in line with the principles of the circular economy.

This study investigates the sustainable use of Eucalyptus spp. bark through different chemical (hydrothermal, acid, alkaline, and bleaching) and physical (milling) pretreatments in the production of sustainable films. Valorization of agro-industrial residues and the demand for sustainable materials pose challenges for environmentally responsible solutions. Eucalyptus spp. bark, rich in cellulose, hemicellulose, and lignin, is a promising source for creating sustainable materials like films. In this study, the use of chemical and physical treatments aims to optimize biomass extraction and improve the chemical, thermal, mechanical, and optical properties of the films. The films showed an excellent light barrier capacity, with a transmittance below 1%. Crystallinity indices varied with the pretreatment: 8.15% for hydrothermal, 7.01% for alkaline, 7.63% for acid, and 10.80% for bleaching. The highest crystallinity value was obtained through bleaching, by removing amorphous components like lignin and hemicellulose. The alkaline pretreatment yielded stronger films (maximum stress of 8.8 MPa, Young’s modulus of 331.3 MPa) owing to the retained lignin and the hemicellulose reinforcing the material. This study contributes to the field of sustainable development by converting residues into valuable materials and by advancing the circular economy. The films’ specific properties make them suitable for applications like sustainable packaging, addressing environmental and industrial challenges.

Expanded polystyrene (EPS) waste is a major environmental concern, yet practical routes to upgrade it into higher value-added materials remain limited. Here, post-consumer EPS was dissolved in ethyl acetate and solvent-cast into films containing cellulose nanocrystals (CNCs) and a sunflower oil. Three formulations were produced: F-EPS (100% EPS), F-EPS + CEL (80% EPS/20% CNC), and F-EPS + CEL + OIL (80% EPS/15% CNC/5% oil). CNC markedly enhanced optical shielding, reducing transmittance at 400 nm from ≈58% (F-EPS) to ≈18% (CNC containing films). All films remained hydrophobic, showed negligible water uptake, and exhibited low mass loss after 30 days of accelerated weathering ($\Delta M=1$–$3\%$). Tensile testing showed that F-EPS had the highest UTS and elongation at break (10.0 ± 0.6 MPa and 10.5 ± 0.4%), whereas adding cellulose increased the elastic modulus (249.5 ± 29.0 MPa to 358.4 ± 64.8 MPa) but reduced UTS and elongation (8.2 ± 0.2 MPa and 5.4 ± 2.5%). Oil addition led to a further reduction in UTS and elongation (6.2 ± 0.4 MPa and 3.6 ± 0.0%), while the modulus returned to a value statistically similar to neat F-EPS. FTIR and XRD confirmed preservation of the EPS chemical fingerprint and a predominantly amorphous structure ($2\theta \approx 20$–30°). Overall, EPS + CNC + OIL films combine hydrophobicity, UV-screening, and elastic modulus similar to neat F-EPS, supporting their use as moisture-resistant, UV screening protective topcoats for non-food-contact paperboard packaging.

The present study aims to evaluate the mechanical properties, colorimetric characteristics, and decay resistance of Pinus elliottii woods treated with oxides synthesized via green chemistry. For this purpose, an aqueous extract from Eucalyptus dunnii leaves was used to synthesize particles based on copper- and zinc-based oxides, as well as a binary oxide system (CuO/ZnO). Sodium polyacrylate was employed as a dispersant, impregnating the oxides into the wood through a horizontal autoclave using a modified Bethell process, assisted by a compressor, applying a pressure of 0.8 MPa for 30 min. The exposure to weathering aging did not significantly alter the mechanical properties of the samples, but it caused the leaching of particles from the treated wood surface, as shown by colorimetric results. Regarding the decay resistance, the copper-based oxide proved to be the most effective treatment against Trametes versicolor (a white-rot fungus), reducing mass loss down to 1.2%. The CuO/ZnO formulation reduced the mass loss caused by Gloeophyllum trabeum to 1.1%, while the zinc oxide showed minimal efficacy. Thus, oxides synthesized via green chemistry using aqueous leaf extracts and mild thermal conditions for synthesis and calcination proved effective in enhancing the wood resistance against biotic deterioration agents.

Poly(vinyl alcohol) (PVA)-based films containing glycerol and quercetin were prepared by casting as potential active-packaging materials. The effects of the glycerol/quercetin ratio on structural, thermal, mechanical, barrier, and antioxidant properties were investigated. Neat PVA and ternary formulations with PVA/glycerol/quercetin ratios of 70/20/10 (PVA+Gly+Q10) and 70/10/20 (PVA+Gly+Q20) by mass were characterized by FTIR, XRD, SEM, contact angle, TGA/DTG, tensile testing, water vapor permeability (WVP), total phenolic content, and DPPH assays. FTIR indicated changes in hydrogen bonding without new covalent functionalities, while apparent whole-film crystallinity indices were 16.2%, 11.1%, and 10.6%, respectively. Tensile tests included additional glycerol-rich and quercetin-rich endpoint controls to characterize the mechanical range of the formulation series. Neat PVA exhibited the highest maximum stress ($15.67\pm 1.49$ MPa). PVA+Gly+Q20 showed a strain at break of $256.87\pm 115.68$% and an apparent tensile modulus of $26.61\pm 3.40$ MPa. The glycerol-rich endpoint exhibited high extensibility, whereas the quercetin-rich endpoint showed a markedly higher apparent tensile modulus ($404.69\pm 45.72$ MPa). DPPH activity increased from 11.18% for PVA to 35.38% and 44.31% for PVA+Gly+Q10 and PVA+Gly+Q20, respectively. PVA+Gly+Q20 also exhibited approximately 68% lower mean WVP than PVA+Gly+Q10, with no significant formulation effect. These results support further development of PVA+Gly+Q20 for active packaging.

Composition‐tunable lignocellulosic aerogels were produced from Eucalyptus spp. bark as adsorbents without additional chemical functionalization. Four formulations comprising cellulose, lignin, and microfibrillated cellulose (MFC) were freeze‐dried: cellulose (CEL), cellulose/MFC (CEL‐M), lignin/MFC (L‐M), and cellulose/lignin/MFC (CEL‐L‐M) aerogels. The samples were characterized by SEM, nitrogen physisorption, XRD, FTIR, density, and porosity. All aerogels exhibited ultralow density and porosity above 99%, with composition‐dependent fibrillar organization, crystallinity, and pore architecture. Bru nauer–Emmett–Teller (BET) surface areas ranged from 0.95 to 7.37 m ² g ⁻¹ for as‐synthesized samples and reached 18.38 m ² g ⁻¹ after Cu ²⁺ adsorption. CEL showed the highest used cooking‐oil uptake (approximately 40 g g ⁻¹ ), whereas CEL‐M performed best for used pump oil (38.81 g g ⁻¹ ). Cu ²⁺ adsorption increased from pH 2 to pH 4–5; CEL‐L‐M reached the highest capacity (1.1337 g g ⁻¹ ) at pH 5 after 30 min, while L‐M reached 0.8964 g g ⁻¹ within 15 min and remained above 1.06 g g ⁻¹ from 30 to 60 min. FTIR changes and Cu detection by EDS supported pH‐regulated binding at oxygen‐containing sites. Accordingly, cellulose, lignin, and MFC contributed differently: CEL maximized cooking‐oil uptake, CEL‐M maximized pump‐oil uptake, while L‐M and CEL‐L‐M provided the fastest Cu ²⁺ uptake and highest capacity, respectively.