Iron-Coated Pine Bark as Biosorbents for Textile Wastewater Treatment: A Sustainable Approach Pedro Gonçalves, Ariana Pintor, Olivia S. G. P. Soares, Manuel F. R. Pereira, Cidália M. S. Botelho, et al. Water Switzerland, 2025 Dyes are widely used in textile processing and are frequently discharged without adequate treatment, posing risks to aquatic ecosystems through reduced water quality, toxicity to organisms, and long-term environmental degradation. To address the need for sustainable remediation solutions, this study investigated the use of pine bark (Pinus pinaster), an abundant forestry byproduct, as a low-cost biosorbent for textile dye removal. Powdered (<0.5 mm) and granular (>1 mm) bark fractions were washed, dried, and modified through iron impregnation (10 wt.% Fe) via sonication in an FeCl3·6H2O solution, with one iron-coated variant subsequently subjected to thermal treatment at 400 °C under nitrogen (1 h) and hydrogen (3 h). Adsorption performance was evaluated using synthetic effluents containing Sirius Blue, Astrazon Red, and Sirius Yellow, individually and as a ternary mixture (80 mg/L each), with added NaCl and NaHCO3 to simulate realistic conditions. Thermally treated granular iron-coated bark showed the highest removal efficiency, achieving >90% dye elimination within 24 h without detectable iron leaching, along with strong iron retention (~80%) and a 53% thermal-treatment yield. Maximum adsorption reached 15.51 mg/g at 5.0 g/L, while lower adsorbent doses increased capacity (26.8 mg/g) but reduced overall removal (~83%). Kinetic analysis was dose-dependent: the pseudo-first-order model provided the best fit at 5.0 g/L, reflecting the rapid approach to equilibrium, whereas the Elovich model fitted best at 2.5 g/L (R > 0.99), consistent with heterogeneous surface interactions under limited adsorbent availability. These results demonstrate the potential of thermally treated iron-coated pine bark as an efficient and sustainable biosorbent for textile wastewater treatment.
Infusion from Opuntia ficus-indica Peels: The Effects of Drying and Steeping Conditions Ricardo M. Ferreira, Dulcineia F. Wessel, Artur M. S. Silva, Jorge A. Saraiva, Susana M. Cardoso Beverages, 2023 The escalating production of processed prickly pear products has led to a substantial rise in waste materials, particularly peel, which is rich in bioactive chemicals and holds the potential for value-added product development. However, the high perishability of these peels imposes effective preservation techniques. So, this work aimed to explore the potential of prickly pear peels from O. ficus-indica ‘Rossa’, ‘Gialla’, and ‘Bianca’ cultivars for the production of Opuntia beverages, namely infusions. To achieve this goal, two distinct drying methods, namely microwave drying and a food dehydrator, were employed with the latter method, resulting in the higher recovery of phenolic compounds (0.5 mgGAE/mL vs. 0.16 mgGAE/mL) and the higher antioxidant capacity of the resulting infusions. Additionally, various steeping conditions involving water temperatures of 80, 90, and 100 °C were assessed to maximize the levels of phenolic compounds and antioxidant activity. The results demonstrate that the better overall drying method temperature and steeping conditions for the food dehydrator were at 35 °C and boiling water (100 °C) due to its generally better results and practicality. Sensorial trials revealed that the three infusions were generally accepted (score > 7.20 out of 9) but that O. ficus-indica ‘Rossa’ received the highest ratings. This study offers valuable insights for optimizing drying methods and steeping conditions to preserve and enhance the bioactive compounds and antioxidant potential in prickly pear peel infusions, promoting their sustainable utilization as functional ingredients in food and nutraceutical applications.
