Lignocellulosic fibers extracted from plants are considered an interesting raw material for environmentally friendly products with multiple applications. This work investigated the feasibility of using hemp- and flax-based materials in the form of felts as biosorbents for the removal of metals present in aqueous solutions. Biosorption of Al, Cd, Co, Cu, Mn, Ni and Zn from a single solution by the two lignocellulosic-based felts was examined using a batch mode. The parameters studied were initial metal concentration, adsorbent dosage, contact time, and pH. In controlled conditions, the results showed that: (i) the flax-based felt had higher biosorption capacities with respect to the metals studied than the hemp-based felt; (ii) the highest removal efficiency was always obtained for Cu ions, and the following order of Cu > Cd > Zn > Ni > Co > Al > Mn was found for both examined biosorbents; (iii) the process was rapid and 10 min were sufficient to attain the equilibrium; (iv) the efficiency improved with the increase of the adsorbent dosage; and (v) the biosorption capacities were independent of pH between 4 and 6. Based on the obtained results, it can be considered that plant-based felts are new, efficient materials for metal removal.

FINEAU (2021–2024) is a trans-disciplinary research project involving French, Serbian, Italian, Portuguese and Romanian colleagues, a French agricultural cooperative and two surface-treatment industries, intending to propose chènevotte, a co-product of the hemp industry, as an adsorbent for the removal of pollutants from polycontaminated wastewater. The first objective of FINEAU was to prepare and characterize chènevotte-based materials. In this study, the impact of water washing and treatments (KOH, Na₂CO₃ and H₃PO₄) on the composition and structure of chènevotte (also called hemp shives) was evaluated using chemical analysis, X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) spectroscopy, X-ray computed nanotomography (nano-CT), attenuated total reflectance–Fourier transform infrared (ATR-FTIR) spectroscopy, solid state NMR spectroscopy and thermogravimetric analysis. The results showed that all these techniques are complementary and useful to characterize the structure and morphology of the samples. Before any chemical treatment, the presence of impurities with a compact unfibrillated structure on the surfaces of chènevotte samples was found. Data indicated an increase in the crystallinity index and significant changes in the chemical composition of each sample after treatment as well as in surface morphology and roughness. The most significant changes were observed in alkaline-treated samples, especially those treated with KOH.

Per- and polyfluoroalkyl substances, known as ‘forever pollutants’ due to their very high stability in ecosystems, are industrial contaminants of emerging health concern commonly found in water. Remediation is particularly challenging because existing water and wastewater treatment plants are not designed to remove these pollutants. Here we review methods for the removal of per- and polyfluoroalkyl substances, with focus on the use of cyclodextrins, the cage molecules that can capture smaller substances. We present classical methods and adsorbents such as granular activated carbons, ion exchange resins, advanced oxidation processes, electrochemical degradation, metal–organic frameworks, and membrane filtration. Cyclodextrin-based materials include cross-linked compounds, molecularly imprinted polymers, covalent organic frameworks, and silica hybrids. We describe the complex formed by inclusion of a per- and polyfluoroalkyl substance into a cyclodextrin. We compare the use of cyclodextrins with other removal methods. Cyclodextrins are cyclic oligosaccharides used to prepare polyfunctional materials by cross-linking, immobilization, coating, or self-assembly. Cyclodextrins-based materials are much more efficient for the remediation of per- and polyfluoroalkyl substances, because these cage molecules can be designed to recognize specifically pollutants. As a consequence, cyclodextrins-based materials display much higher adsorption coefficients, in the range of 10 ⁴ —10 ⁶ L per Kg, compared to less than 10 ⁴ L per Kg for activated carbon.

Trifluoroacetic acid (TFA), often referred to as the simplest “Forever Chemical,” is a highly persistent environmental contaminant. Despite increasing concern about its potential toxicity, analytical data on its occurrence in drinking water remain limited. In this study, TFA was quantified in 63 household tap water samples from Besançon (France) and 71 bottled water samples purchased in France, Italy, and Romania. The 26 participating French households were recruited on a voluntary basis, and samples were collected randomly over a six-month period. TFA was detected in 100% of the tap water samples, with concentrations ranging from 540 to 3800 ng/L (mean: 1164 ± 594 ng/L; median: 1000 ng/L). In bottled water, TFA was also detected in all French samples, though at lower levels (mean: 297 ± 268 ng/L; median: 280 ng/L). Concentrations in Italian and Romanian bottled water ranged from below the detection limit to a maximum of 400 ng/L. These findings highlight the widespread presence of TFA in drinking water, with higher concentrations in tap water compared to bottled water, except for one outlier brand. The results support the need for further monitoring and assessment of TFA as an emerging contaminant in European water systems. Graphical abstract