Ionic liquids (ILs) formed by multivalent cations are generally of higher thermal and electrochemical stability, which makes them attractive for use in high-temperature applications. Whereas the influence of structural elements on the physicochemical properties of dicationic ILs (DILs) is well established, such systematic investigations on their ecotoxicity and biodegradablility are still lacking. The present study investigates the influence of the dicationic structural elements on these characteristics and addresses the question whether already established structure-activity relationships of common ILs can be applied to DILs.Therefore, a set of 10 DILs with different linkage chain length, terminal alkyl side chain length, linkage chain polarity and head groups were synthesized and studied in several biodegradation and toxicity tests. The results showed that the acute toxicity was in many cases below the levels observed for monocationic ILs. However, none of the DILs could be degraded within the performed biodegradation experiments. Hence, DILs are a potential less toxic alternative to monocationic ILs, but further work on their design is necessary.

Components of natural waters (salts, NOM) mitigate negative impacts of nanomaterials via surface passivation and stabilisation against dissolution.

Many interesting applications of magnetic iron oxide nanoparticles (IONPs) have recently been developed based on their magnetic properties and promising catalytic activity. Depending on their intended use, such nanoparticles (NPs) are frequently functionalized with proteins, polymers, or other organic molecules such as meso-2,3-dimercaptosuccinic acid (DMSA) to improve their colloidal stability or biocompatibility.Although the coating strongly affects the colloidal properties and environmental behaviour of NPs, quantitative analysis of the coating is often neglected. To address this issue, we established an ion chromatographic method for the quantitative analysis of surface-bound sulfur-containing molecules such as DMSA. The method determines the amount of sulfate generated by complete oxidation of sulfur present in the molecule. Quantification of the DMSA content of DMSA-coated IONPs showed that reproducibly approximately 38% of the DMSA used in the synthesis was adsorbed on the IONPs. Tests for the biodegradability of free and NP-bound DMSA using a microbial community from a wastewater treatment plant showed that both free and NP-bound DMSA was degraded to negligible extent, suggesting long-term environmental stability of DMSA-coated IONPs.