Technische Universität Darmstadt

Abstract: The transition to sustainable hydrogen and carbon economies is essential for addressing critical global issues such as climate change, resource depletion, and waste management.A vital strategy for low-carbon sustainability in the energy and chem. sectors is the chem. conversion of greenhouse gas into fuels and platform chems.Effective waste management, including waste-to-energy conversion and recycling, plays a crucial role in reducing emissions and promoting a circular economy.A key aspect of this transition is the development of innovative technologies that can transform waste into valuable resources while minimizing environmental impacts.Plasma-based recycling presents a promising solution, offering remarkable versatility for applications like waste upcycling and greenhouse gas conversion.These processes play a crucial role in advancing the development of sustainable carbon and hydrogen economies.

Persistent and mobile trace organic contaminants (TrOCs) in urban stormwater are difficult to remove through sedimentation- or sorption-based treatment and pose a risk to aquatic ecosystems and drinking water supplies. We demonstrate that the chemical oxidant peroxydisulfate (PDS) can be activated by shrimp shell biochar at pH 7 to form reactive species that selectively react with widespread stormwater contaminants. Of 11 TrOCs tested, oxidative transformation was observed for 1,3-diphenylguanidine, 2-hydroxybenzothiazole, 1H-benzotriazole, 5-methyl-benzotriazole, and diuron during water treatment with biochar and PDS. Laboratory batch experiments conducted with street runoff and a synthetic water showed that the water matrix, containing up to 7.5 mg L^-1 dissolved organic carbon and 100 mM chloride, had a minor effect on the formation of reactive species and contaminant transformation. Using a set of scavengers and probe compounds, we provide evidence for singlet oxygen (¹O₂) as the predominant reactive species in the biochar/PDS system, which is in agreement with the selectivity of the process to oxidize electron-rich organic contaminants. The results of our study inform new strategies for stormwater treatment using heterogeneous oxidation processes for the abatement of persistent and mobile organic contaminants.

The dynamics of nanoparticle-laden droplets, from dripping to impact, have remained a subject of intense debate due to conflicting reports in the literature. Here, we address this controversy by systematically investigating the breakup, impact, spreading, and splashing behavior of fully characterized additive-free silica nanosuspensions synthesized via the Stöber process. In the absence of additives, we find that nanoparticles exert negligible influence on the fluid viscosity and dynamic behavior of droplets during break up, spreading, and splashing - even in suspensions with a high loading concentration (15 wt.%). This work highlights the pivotal role of additives, dispersants, and interparticle interactions in governing droplet behavior. Our findings offer crucial insights for a wide range of fields, including inkjet printing and spray coating.