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- Difenoconazole (1)
- Dynamic scanning calorimetry (1)
- Environment (1)
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A first pilot study on the sorption of environmental pollutants on various microplastic materials
(2017)
With the drastic increase in plastic production, the input of plastic particles into the environment has become a recognised problem.
Xenobiotics are able to sorb to polymer materials, and this process is further enhanced where they Encounter microplastics (plastic fragments <5 mm). In this work we studied the sorption of metformin, a type-2 diabetes drug, and difenoconazole, a fungicide, onto the virgin polymer materials polyamide (PA), polypropylene (PP), and polystyrene (PS). Additionally, PP was cryo-milled and PA was treated with acid to investigate the influence of an increase in surface area and chemical modification. The material properties were also studied by dynamic scanning calorimetry (DSC), gel permeation chromatography (GPC) and Fourier transform infrared spectroscopy (FTIR). Sorption experiments were performed on the basis of a full factorial design examining the effect of agitation, pH value, and salinity. Experimental results showed that difenoconazole sorbs readily to all microplastics, whereas the more polar analyte metformin did not show any affinity to the materials used. For difenoconazole the governing factor in all cases is agitation, while both pH and salinity exhibited only a slight influence. The modification of polymers leads to enhanced sorption, indicating that an increase in surface area (cryo-milled PP) or inner volume (acid-treated PA) strongly favours adsorption. Moreover, long-term experiments demonstrated that the time until equilibrium is reached depends strongly on the particle size.
Plastics are a diverse group of materials used in packaging, construction, medical applications, and many more. Due to their favourable properties their production and consequently their input into natural systems has increased drastically over the last decades. In the environment (photo-)oxidation processes and mechanical abrasion may then lead to the decomposition of the plastics. During this process microplastics (<5 mm) are formed. It has been noted that xenobiotics which are present in the same compartments can sorb to microplastics. However, knowledge on this topic is still limited. The work presented here aimed to investigate the sorption of the type 2 diabetes drug metformin and the triazole fungicide difenoconazole to virgin polyamide (PA), polypropylene (PP), and polystyrene (PS). Additionally, sorption to cryo-milled PP and acid-treated PA was studied. The latter was also characterised by Fourier transform infrared spectroscopy (FTIR), gel permeation chromatography (GPC), and dynamic scanning calorimetry (DSC). Sorption experiments were planned on the basis of a full factorial design with agitation, salinity, and pH value as parameters. Results of the study revealed that metformin did not show any affinity towards the tested materials. Difenoconazole however, sorbed to all microplastics. Data analysis showed that agitation is the main influencing factor, whereas salinity and the pH value held little to no significance. Mechanical and chemical treatment of the polymers led to enhanced sorption of difenoconazole. Long-term sorption experiments confirmed the hypothesis that particle size strongly influences the time until sorption-desorption equilibrium is reached.