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Your search keyword '"Kah, Melanie"' showing total 9 results
Start Over Author "Kah, Melanie" Publisher royal society of chemistry
9 results on '"Kah, Melanie"'

3. Tebuconazole and terbuthylazine encapsulated in nanocarriers: preparation, characterization and release kinetics

Author

López-Cabeza, Rocio, Kah, Melanie, Grillo, Renato, Koutný, Marek, Salač, Jan, Bílková, Zuzana, Eghbalinejad, Mahleh, Hofman, Jakub, López-Cabeza, Rocio, Kah, Melanie, Grillo, Renato, Koutný, Marek, Salač, Jan, Bílková, Zuzana, Eghbalinejad, Mahleh, and Hofman, Jakub

Abstract

In this work, tebuconazole and terbuthylazine were encapsulated in nanocarriers prepared from the polymers poly-epsilon-caprolactone, poly(3-hydroxybutyrate) and poly(acrylic acid)/polylactide, and in a nanostructured lipid carrier. The release kinetics of the prepared nanoformulations was assessed by the dialysis method and the results obtained from these release experiments were related to the durability of the nanoformulations. The outcomes suggested that the release of the active ingredients in these nanoformulations depended mainly on the interaction between the nanocarrier materials and the pesticides. In addition, it was found that the durability of the complex formed by tebuconazole encapsulated in poly(3-hydroxybutyrate) was affected by its dilution, the durability being shorter with the increase of dilution factor. The findings in this work could help the design of pesticide nanoformulations with certain durability according to the pesticide doses required in the field by selecting the appropriate nanocarrier material. Likewise, the results indicate the need to evaluate the release kinetics of the active ingredients under dilution of the nanoformulations, since the dilution in the mixing tank before application or in the soil during irrigation or rainfall events could influence the durability of the nanoformulations and as a consequence, their environmental risk assessment.

Published
2022

4. Environmental fate of nanopesticides: durability, sorption and photodegradation of nanoformulated clothianidin† †Electronic supplementary information (ESI) available. See DOI: 10.1039/c8en00038g

Author

Kah, Melanie, Walch, Helene, and Hofmann, Thilo

Subjects
Chemistry
Abstract

A lot of research efforts are currently dedicated to the development of nano-enabled agrochemicals. It is thus urgent to develop suitable strategies for their ecological assessment., A lot of research efforts are currently dedicated to the development of nano-enabled agrochemicals. Knowledge about their environmental behaviour is however scarce, which impedes the assessment of the new risk and benefits relative to currently used agrochemicals. With the aim to advance our understanding of the fate of nanopesticides in the environment and support the development of robust exposure assessment procedures, the main objectives of the study were to (i) investigate the extent to which three nanoformulations can affect the photodegradation and sorption of the insecticide clothianidin, and (ii) evaluate various approaches to estimate durability, a key parameter for the exposure assessment of nanopesticides. The nanoformulations increased the photodegradation half-life in water by a maximum of 21% relative to the conventional formulation. Sorption to soil was investigated by two methods and over time, and results show that sorption was increased by up to 51% and 10%, relative to unformulated clothianidin and the commercial formulation, respectively. Our results generally indicate that nanoformulations may have a greater impact on the fate of pesticide active ingredients than commercial formulations. It is important to note however that differences in fate parameters were generally very moderate, including in realistic worst-case conditions (high pesticide concentration and ionic strength). Our results collectively suggest that clothianidin was rapidly released from the nanocarrier systems and that the durability of the three nanoformulations would be short in water as well as in soil environments (including under realistic soil to solution ratio). The durability of nanoformulations after their application in the environment is an essential parameter that needs to be characterised for the development as well as for the evaluation of nano-enabled agrochemicals. This study illustrates how performances of nano-enabled products can be critically benchmarked against existing products to support an objective assessment of new environmental risks and benefits. In this context, the fate of the nanocarrier system is of great interest and should be the topic of further research.

Published
2018

9. Effect of ageing on the properties and polycyclic aromatic hydrocarbon composition of biochar.

Author

Sigmund, Gabriel, Bucheli, Thomas D., Hilber, Isabel, Micić, Vesna, Kah, Melanie, and Hofmann, Thilo

Abstract

The influence of ageing on biochar properties has been investigated by comparing three fresh biochars with biochars artificially aged by either H2O2 thermal oxidation or horseradish peroxidase enzymatic oxidation. In addition, a field-aged counterpart for one of the biochars was recovered from an agricultural field site, four years after application. Biochar properties, including surface areas and pore volumes (derived by N2 and CO2 physisorption) and elemental compositions, showed only minor changes following both artificial and field ageing, indicating high biochar stability. Concentrations of the 16 US EPA PAHs were measured in all of the biochars and a contaminant trap was used to investigate the effect of ageing on their bioaccessibility. The concentrations of total and bioaccessible PAHs ranged from 4.4 to 22.6 mg kg−1 and 0.0 to 9.7 mg kg−1, respectively. Concentrations of the 16 US EPA PAHs decreased following field ageing, but the proportion of low molecular weight PAHs increased. The observed changes in PAH composition with field ageing can be explained by uptake from the surrounding soil and intra-biochar transfer processes. To better understand changes in PAH composition with ageing, an additional broad range of alkylated PAHs was also analyzed in selected samples. Our results show that the tested artificial ageing protocols are unable to approximate the changes in PAH composition resulting from field ageing. Nevertheless, total and bioaccessible PAH concentrations decreased for both artificially and field-aged biochars, indicating that biochars release PAHs when they are freshly produced and that the risk of PAH release decreases with ageing. [ABSTRACT FROM AUTHOR]

Published
2017
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