Cyclodextrines réticulées pour traiter des eaux contaminées

International audienc

Decontamination of polluted discharge waters from surface treatment industries by pressure-driven membranes: Removal performances and environmental impact

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A Strategy to Valorize a By-Product of Pine Wood (Pinus pinaster) for Copper Removal from Aqueous Solutions

This study describes the valorization of a pine wood by-product (Pinus pinaster) in the form of individualized fibers to a complex copper or more broadly metals present in an aqueous solution using a batch process. The adsorption results show that pine fibres activated by sodium carbonate are effective in recovering copper ions from monocontaminated or polycontaminated solutions of varying concentrations in a few minutes. One gram of material captures 2.5 mg of copper present in 100 mL of solution at pH 5 in less than 10 min. The results are perfectly reproducible and independent of pH between 3 and 5. The presence of the Na+ cation at concentrations of 0.1 M has no impact on material performance, unlike that of Ca2+ ions, which competes with Cu2+ ions for active sites. The adsorption process can be considered as rapid, as most of the copper is adsorbed within the first 10 min of exposure. Investigation of modeling possibilities shows some limitations. Indeed, the Weber and Morris and Elovich models show poor possibilities to describe all the kinetic data for copper adsorption on fibres. This may prove that the mechanism is far more complex than simple physisorption, chemisorption and/or diffusion. Complexation by wood fibers can be extended to solutions containing several types of metals. The results of this study show that the field of selective metal recovery could be a new way of valorizing by-products from the wood industry

Characterization of Cyclodextrin Cross-linked Polymers Used in Environmental Applications by Solid-state NMR Spectroscopy: a Historical Review

Cross-linked cyclodextrin polymers are attracting increasing interest not only from the scientific community but also from industry. These commercial polymers, discovered in the late 1960s, have applications in many fields, from pharmaceuticals to food processing, chromatography, cosmetics, membrane materials, and the environment. More recently, this class of functional polymers have been proposed as biosorbents to treat wastewater contaminated by conventional pollutants, such as metals, polycyclic aromatic hydrocarbons, phenols, and dyes, or emerging pollutants such as hormones, antibiotics, alkylphenols, and fluorine derivatives. However, although many results have been published, many questions remain not only on the chemical structure of the macromolecular networks of these polymers but also on the biosorption mechanisms involved in their use as biosorbents to treat pollutants. Solid-state NMR spectroscopy can help to answer these questions. This chapter aims to summarize and discuss the role of solid-state NMR spectroscopy in characterizing the structure of cross-linked cyclodextrin polymers and the interactions involved in biosorption using the state of the art and our own research results obtained over 25 years

Biosorbents from plant fibers of hemp and flax for metal removal: Comparison of their biosorption properties

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

Corticosterone mediates telomere length in raptor chicks exposed to chemical mixture

Stressors experience early in life by animals may have carry over impacts on life-traits over the life cycle. Accelerated telomere attrition induced by stress during development and growth could play a role in such delayed effects. Among stressors, exposure to chemicals may modify telomere dynamic but, to date, the trends evidenced between exposure and telomere shortening remains inconsistent. Moreover, the role of corticosterone as a possible mediator of chemical impact on telomere is not yet clearly established. Here, we investigated in wild populations of Red kite whether nestling exposure to metals and pesticides was related to corticosterone concentrations in feathers and telomere length measured in 47 individuals. Lead and mercury concentrations in blood ranged from 2.3 to 59.0 µg L−1 and to 1.4 to 115.7 µg L−1, respectively, and were below the toxicity thresholds proposed for wildlife. Rodenticides were detected in 30% of the chicks. Corticosterone increased with mercury and lead in interaction, showing a synergistic effect of these 2 non-essential metals on this stress hormone. Telomere length was not linked to metals and/or rodenticide exposure while it was related negatively to corticosterone. The relationship between telomere and corticosterone was modulated by nestling’s age, which suggests that the rate of telomere shortening is higher when corticosterone increases. Our findings propose an effect of low exposure of Red Kite nestlings to mercury and lead mixture to raise baseline corticosterone in feathers. The relationships established suggest the hypothesis that telomere attrition could be an indirect consequence of metal exposure mediated by corticosterone

Bioaccessibility of metal(loid)s in soils to humans and their bioavailability to snails: A way to associate human health and ecotoxicological risk assessment?

International audienceHuman health risk assessment (HHRA) and ecotoxicological risk assessment (ERA) of contaminated soils are frequently performed separately and based on total soil concentrations without considering the concepts of mobility, bioaccessibility and bioavailability. However, some chemical and biological assays rarely used in combination can be applied to more accurately assess the exposure of organisms to metal(loid)s and thus to better estimate the links between soil contamination and effects. For humans, the unified bioaccessibility method (UBM) assesses oral bioaccessibility, while for soil fauna such as land snails, the bioaccumulation test reflects the bioavailability of contaminants. The aim of this study is to explore the relationship between oral bioaccessibility and the bioavailability of arsenic, cadmium and lead in twenty-nine contaminated soils. The results show a modulation of bioaccumulation and bioaccessibility of metal(loid)s by soil physicochemical parameters (organic matter especially). For the three metal(loid)s studied, strong relationships were modelled between the UBM and snail tests (0.77 < r²adj.<0.95), depending on the parameters of the linear regressions (contaminant and phases of the UBM test). The original models proposed demonstrate the feasibility of linking bioaccessibility to humans and bioavailability to snails and the relevance of their association for an integrative risk assessment of contaminated soils

Use of chènevotte, a valuable co-product of industrial hemp fiber, as adsorbent for copper ions: Kinetic studies and modeling

In this study, a series of hemp shives (chènevotte) with different chemical compositions and properties, namely a raw (SHI-R), a washed with water (SHI-W), three samples chemically modified with KOH (SHI-OH), Na2CO3 (SHI-C) or H3PO4 (SHI-H), and a hemp shives sample prepared by grafting of carboxylic groups (SHI-BTCA), were used as adsorbents for the removal of copper present in aqueous solutions. This article presents the abatements and kinetics obtained using batch experiments and their modeling. The results first showed that the quantity of copper removed depended on the used shives and the copper initial concentration. At the same experimental conditions, SHI-C and SHI-BTCA samples possessed similar performances which are significantly higher than those of other studied hemp shives. Copper adsorption reached equilibrium after 60 min of contact time and was independent of concentration in the range 5–150 mg/L for SHI-C and SHI-BTCA. According to the better Chi-squared values, the experimental data were better simulated by the non-linear kinetic model in the order: Lagergren &lt; Elovich &lt; Ho and McKay &lt; Weber and Morris &lt; Boyd for SHI-C and Boyd &lt; Ho and McKay &lt; Weber and Morris &lt; Lagergren &lt; Elovich for SHI-BTCA. The analysis of data indicated that chemisorption is the main mechanism for binding copper onto SHI-BTCA, while physisorption (diffusion) is the main interaction for copper adsorption onto SHI-C. The adsorption-oriented process using hemp shives could be an advantageous approach for recovering copper from metal industry effluents due to the simplicity of the process, its efficiency to treat both diluted and concentrated copper solutions, and the low-cost, non-toxic to humans and the environment, ecological character, and facile use of hemp shives

Early screening of new accumulating versus non-accumulating tree species for the phytomanagement of marginal lands

International audienceThe use of fast-growing trees producing a high quantity of biomass can bring significant practical and economic benefits to the reclamation of marginal lands. The present study aims to identify new shrub/tree species to offer a wider range of shrubs/trees useful for phytomanagement practices. We implemented three experimental sites in France of 1 ha each (Thann, Carrières-sous-Poissy and Leforest) contaminated by different potentially toxic elements (PTE) with a total of 38 different tree species. After two years of growth, the element concentrations in stem and leaf biomasses, tree survival rate and growth of plants were assessed. Although the three sites had elevated concentrations of total PTE and nutrients in their soil, the element contents in the trees strongly differed depending on the species. Alnus subcordata, Platanus orientalis, Ulmus pumila, Ostrya carpinifolia and the Acer species appeared to be well adapted to the drastic conditions of the sites and presented the lowest PTE concentrations in their aboveground biomass. Conversely, the Salix, Populus, Betula and Quercus species, especially Salix aquatica grandis, exhibited the highest accumulations of Cd, Zn and/or Mn at the three sites. Inoculation with the endomycorrhizal fungus Rhizophagus irregularis did not have a significant impact on the growth of the tree species at the three sites after two growing seasons. Overall, the present study offers two options for the phytomanagement of marginal lands. The first option is based on the production of clean biomass, which is useful for plant-based industrial processes (e.g., biomaterials, bioenergy) that could valorize this biomass. The second option is based on the production of TE-enriched biomass that could be better exploited in the eco-catalysis process