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- Aktivkohle (4)
- Thermogravimetrie (4)
- Adsorption (3)
- Microplastic (2)
- Powdered activated carbon (2)
- TED-GC/MS (2)
- AIS QD (1)
- Adsorbtion (1)
- Advanced wastewater treatment (1)
- Belebtschlamm (1)
Organisationseinheit der BAM
In diesem Beitrag wird der Einfluss des Aktivkohleprodukts auf die Adsorption von Spurenstoffen aus Kläranlagenablauf gezeigt und diskutiert. Im zweiten Teil wird das Material Aktivkohle analytisch charakterisiert und die Eigenschaften systematisiert. Die gewonnenen Erkenntnisse werden mit Bezug zu Praxislösungen zusammengefasst.
Water treatment with activated carbon (AC) is an established method for the removal of organic micropollutants and natu ral organic matter. However, it is not yet possible to predict the removal of individual pollutants. An appropriate material characterization, matching adsorption processes in water, might be the missing piece in the puzzle. To this end, this study examined 25 diferent commercially available ACs to evaluate their material properties. Frequently reported analyses, including N2 adsorption/desorption, CHNS(O), point of zero charge (PZC) analysis, and X-ray photoelectron spectroscopy, were conducted on a selected subset of powdered ACs. Inorganic elements examined using X-ray fuorescence and X-ray difraction spectroscopy revealed that relative elemental contents were distinctive to the individual AC’s raw material and activation procedure. This study also is the frst to use thermogravimetric analysis (TGA) coupled to Fourier-transform infrared spectroscopy (FTIR) to conduct quantitative analyses of functional surface oxygen groups (SOGs: carboxylic acid, anhydride, lactone, phenol, carbonyl, and pyrone groups) on such a large number of ACs. The comparably economical TGA method was found to provide good surrogates for the PZC by pyrolytic mass loss up to 600 ◦C (ML600), for the oxygen content by ML1000 and for the carbon content by oxidation. Mass loss profles depict the AC’s chemistry like fngerprints. Furthermore, we found that SOG contents determined by TGA-FTIR covered a wide individual range and depended on the raw material and production process of the AC. TGA and TGA-FTIR might therefore be used to identify the suitability of a particular AC for a variety of target substances in diferent target waters. This can help practitioners to control AC use in waterworks or wastewater treatment plants.
The occurrence of small particles consisting of organic polymers, so-called microplastic (MP), in aquatic Environments attracts increasing interest in both public and science. Recent sampling campaigns in surface Waters revealed substantial numbers of particles in the size range from a few micrometers to a few millimeters. In order to validate sample preparation, identification and quantification and to investigate the behavior of MP particles and potential toxic effects on organisms, defined MP model particles are needed. Many studies use spherical compounds that probably behave differently compared to irregularly shaped MP found in environmental samples.
However, preparation and handling of MP particles are challenging tasks and have been systematically investigated in the present study. Polystyrene (PS) as a commonly found polymer with a density slightly above that of water was selected as polymer type for milling and fractionation studies. A cryogenic ball mill proved to be practical and effective to produce particles in the size range from 1 to 200 μm. The yield of small particles increased with increasing pre-cooling and milling durations. Depending on the concentration and the size, PS particles do not completely disperse in water and particles partly creep vertically up along glass walls. Stabilized MP suspensions without use of surfactants that might harm organisms are needed for toxicological studies. The stabilization of PS particle suspensions with ozone treatment reduced the wall effect and increased the number of dispersed PS particles but increased the dissolved organic carbon concentration and changed the size Distribution of the particles.