Sanitär- und Kommunaltechnik; Umwelttechnik
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n order to determine the relevance of microplastic particles in various environmental media, comprehensive investigations are needed. However, no analytical method exists for fast identification and quantification. At present, optical spectroscopy methods like IR and RAMAN imaging are used. Due to their time consuming procedures and uncertain extrapolation, reliable monitoring is difficult. For analyzing polymers Py-GC-MS is a standard method. However, due to a limited sample amount of about 0.5 mg it is not suited for analysis of complex sample mixtures like environmental samples. Therefore, we developed a new thermoanalytical method as a first step for identifying microplastics in environmental samples. A sample amount of about 20 mg, which assures the homogeneity of the sample, is subjected to complete thermal decomposition. The specific degradation products of the respective polymer are adsorbed on a solid-phase adsorber and subsequently analyzed by thermal desorption gas chromatography mass spectrometry. For certain identification, the specific degradation products for the respective polymer were selected first. Afterwards real environmental samples from the aquatic (three different rivers) and the terrestrial (bio gas plant) systems were screened for microplastics. Mainly polypropylene (PP), polyethylene (PE) and polystyrene (PS) were identified for the samples from the bio gas plant and PE and PS from the rivers. However, this was only the first step and quantification measurements will follow.
In order to determine the relevance of microplastic particles in various environmental media, comprehensive investigations are needed. However, no analytical method exists for fast identification and quantification. At present, optical spectroscopy methods like IR and RAMAN imaging are used. Due to their time consuming procedures and uncertain extrapolation, reliable monitoring is difficult. For analyzing polymers Py-GC-MS is a standard method. However, due to a limited sample amount of about 0.5 mg it is not suited for analysis of complex sample mixtures like environmental samples. Therefore, we developed a new thermoanalytical method as a first step for identifying microplastics in environmental samples. A sample amount of about 20 mg, which assures the homogeneity of the sample, is subjected to complete thermal decomposition. The specific degradation products of the respective polymer are adsorbed on a solid-Phase adsorber and subsequently analyzed by thermal Desorption gas chromatography mass spectrometry. For certain identification, the specific degradation products for the respective polymer were selected first. Afterwards real environmental samples from the aquatic (three different rivers) and the terrestrial (bio gas plant) systems were screened for microplastics. Mainly polypropylene (PP), polyethylene (PE) and polystyrene (PS) were identified for the samples from the bio gas plant and PE and PS from the rivers. However, this was only the first step and quantification measurements will follow.
Waste disposal of carbon nanotube (CNT) containing products is expected to be the most important pathway for release of CNTs into the environment. In the present work, the use of radiolabelled CNTs (14C-CNT) for polycarbonate polymer nanocomposites with 1 wt% 14C-CNT content allowed for the first time to quantify and differentiate the CNT release according to the type of impact along the materials' ageing history. After an initial exposure of the nanocomposite by solar-like irradiation, further environmental impacts were applied to composite material. They aimed at mimicking disposal site conditions that may induce further ageing effects and CNT release. This study included shaking in water, rapid temperature changes, soaking in humic acid solution as well as waste water effluent, and, finally, gentle mechanical abrasion. All ageing impacts were applied sequentially, both on pristine (control) and on solar-irradiated nanocomposites. All experiments were accompanied by absolute quantification of radioactive release as well as chemical and morphological analyses of the nanocomposite surfaces using infra-red (IR) spectroscopy, X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). The morphological analysis showed that spectral irradiation can uncover CNT networks on the outer nanocomposite surface layers by polymer degradation. After having subjected the solar-irradiated nanocomposite to all studied disposal site effect, the total radioactive release was quantified to amount to 64 mg CNT/m2, whereas only 0.8 mg CNT/m2 were found for the un-irradiated control sample. Solar degradation of polymers was thus found to significantly increase the propensity of the studied polymer nanocomposites to release CNTs during ageing effects at the product's end-of-life typical for disposal sites.
Monitoring the ingestion of microplastics is challenging and suitable detection techniques are insufficiently used. Thus, misidentifying natural for synthetic microfibres cannot be avoided. As part of a framework to monitor the ingestion of microplastics in eelpout, this short report addresses the accurate identification of microfibres. We show that, following visual inspections, putatively synthetic microfibres are indeed of natural origin, as ascertained by spectrometric analyses. Consequently, we call for an inclusion of spectroscopic techniques in standardized microplastic monitoring schemes.