Sorption

Résumé

vignette|redresse=1.5|Illustration de la différence entre absorption et adsorption. La sorption est le processus par lequel une substance est adsorbée ou absorbée (par un « sorbant ») sur ou dans une autre substance. Elle résulte de l'action de molécules de gaz ou de liquide mises en contact avec un matériau solide, et qui adhèrent à sa surface (adsorption) ou s'incorporent dans la totalité de son volume (absorption). Dans les deux cas, les molécules fixées ne sont plus présentes dans le solvant. La désorption est la transformation inverse de la sorption, par laquelle les molécules sorbées se détachent du substrat. Applications La sorption, en particulier l'adsorption, ainsi que la désorption, jouent un rôle crucial dans le comportement des substances toxiques, par exemple pour les substances organiques dans l'air (fixation des particules d'aérosol). Les substances toxiques peuvent également se fixer durablement à des particules du sol. La sorption est utilisée pour la c

Source officielle

https://fr.wikipedia.org/wiki/Sorption

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Many studies have reported that hydrophobic organic contaminants have the ability to sorb on microplastics in aquatic ecosystem via different mechanisms of sorption. However, a lack of studies investigating desorption of such contaminants in organism fluids has been disclaimed. The bioavailability of potential risk-compounds for aquatic organisms has to be assessed. It has been largely reported that adsorption onto microplastics is directly linked with hydrophobicity property of contaminants; the more hydrophobic the pollutant, the higher the sorption capacity. However, it is expected that the least hydrophobic molecules desorb more easily from microplastics. In our study, steroid hormones with different hydrophobicities, namely progesterone and testosterone, are used and their respective desorption from different types of microplastics is investigated in gastric and gut fluids. The idea is to discern if the ingestion of microplastics by organisms might promote desorption of potential sorbed micropollutants and therefore their bioavailability for such species. By using more complex composition of gastric and intestinal fluids separately and then sequentially, the purposes are to reproduce realistic digestive conditions and furthermore determine the organ which is the most prompt to enhance bioavailability of pollutants. Our results show that a higher desorption efficiency (58.6-73.0%, depending on plastic types) is reached in intestinal fluid than in freshwater (31.1-53.6%) or in gastric fluid (18.7-43.9%). Bile salts in intestinal fluid form micelles able to promote the solubilization of pollutants. Adsorption of pepsin onto microplastics has also been revealed, suggesting a competition between pollutant and pepsin for sorption sites and a potent reduction of pollutant solubilization. Our results indicate that progesterone daily intake via microplastics exposure is equal to 16.0μg/kg/day upon intestinal digestion, which represents about 13% of daily intake via water exposure. This observation suggests that ingestion is an additional route of exposure of pollutants and therefore emphasizes pollutants bioavailability for aquatic organisms.

2020

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Adsorption of progesterone onto microplastics and its desorption in simulated gastric and intestinal fluids

Florian Frédéric Vincent Breider, Dominique Grandjean, Yang Liu, Thibault Béranger Masset, Cécilia Laetitia Carla Siri

The sorption of Hydrophobic Organic Compound (HOC) onto microplastics is relatively well reported in the literature, while their desorption remains poorly investigated, and especially in biological ﬂuids. The present study investigated the sorption and desorption of progesterone on polyethylene (PE), polypropylene (PP) and polystyrene (PS) microplastics. The sorption experiments showed that the equilibrium was reached in a few hours for all plastics. A sorption efﬁciency of 357.1 µg/g was found for PE and PS and 322.6µg/g for PP. Sorption experiments indicated that adsorption would happen certainly via surface sorption and potentially pore-ﬁlling mechanism. The desorption was carried out in Simulated Gastric Fluid (SGF) and Simulated Intestinal Fluid (SIF), whose formulations were more complex than similar models reported so far. It has been found that the desorption was higher in SIF compared to SGF, surely due to micelle formation in SIF promoting the pollutant solubilization. Sorption of pepsin onto microplastics has also been revealed, suggesting a competition between pollutant and pepsin for sorption sites and a potent reduction of pollutant solubilization. This study indicates that microplastics ingestion could be considered as as additional route of exposure of pollutants and therefore emphasizes pollutants bioavailability for aquatic organisms.

2021

Chargement

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The sorption of hydrophobic organic compounds onto microplastics is relatively well reported in the literature, while their desorption remains poorly investigated, especially in biological fluids. The present study investigated the sorption and desorption of progesterone on polyethylene (PE), polypropylene (PP), and polystyrene (PS) microplastics. A sorption efficiency of 357.1 mg g-1 was found for PE and PS, and 322.6mg g-1 for PP. Sorption experiments indicated that adsorption would certainly happen via surface sorption and a potentially pore-filling mechanism. The desorption was carried out in Simulated Gastric Fluid (SGF) and Simulated Intestinal Fluid (SIF). It has been found that the desorption was higher in SIF as compared to SGF, due to micelle formation in SIF promoting the pollutant solubilization. This study indicates that the ingestion of microplastics could be considered as an additional route of exposure to pollutants and therefore emphasizes pollutant bioavailability for aquatic organisms.

2022

Chargement

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2020