Analysis of Dibenzyltoluene Mixtures: From Fast Analysis to In-Depth Characterization of the Compounds.

The so-called dibenzyltoluene (H0-DBT) heat transfer oil contains numerous isomers of dibenzyltoluene as well as (benzyl)benzyltoluene (methyl group on the central vs. the side aromatic ring). As it is used as a liquid organic hydrogen carrier (LOHC), a detailed analysis of its composition is crucial in assessing the kinetic rate of hydrogenation for each constituent and studying the mechanism of H0-DBT hydrogenation. To identify all of the compounds in the oil, an in-depth analysis of the GC-MS spectra was performed. To confirm peak attribution, we synthesized some DBTs and characterized the pure compounds using NMR and Raman spectroscopies. Moreover, a fast-GC analysis was developed to rapidly determine the degree of hydrogenation of the mixture.

Metal oxide nanoparticles for the decontamination of toxic chemical and biological compounds.

For several years, the international context is deeply affected by the use of chemical and biological weapons. The use of CBRN (Chemical Biological Radiological Nuclear) threat agents from military stockpiles or biological civilian industry demonstrate the critical need to improve capabilities of decontamination for civilians and military. Physical decontamination systems that operate only by adsorption and displacement such as Fuller's Earth, have the drawback of not neutralizing hazardous agents, giving place to cross contaminations. Consequently, the development of a formulation based on metal oxide nanoparticles attracts considerable interest, since they offer physicochemical properties that allow them to both adsorb and degrade toxic compounds. Thus, the aim of this study is to found metal oxide nanoparticles with a versatile activity on both chemical and biological toxic agents. Therefore, several metal oxides such as MgO, TiO2, CeO2, ZnO and ZrO2 were characterized and their decontamination kinetics of less-toxic surrogate of VX, paraoxon, were studied in vitro. To determine the antimicrobial activity of these nanoparticles, simulants of biological terrorist threat were used by performing a 3-hours decontamination kinetics. This proof-of-concept study showed that MgO is the only one that exhibits both chemical and antibacterial actions but without sporicidal activity.

Shape-selective synthesis of nanoceria for degradation of paraoxon as a chemical warfare simulant.

Repeated attacks using organophosphorus compounds, in military conflicts or terrorist acts, necessitate developing inexpensive and readily available decontamination systems. Nanosized cerium oxide is a suitable candidate, acting as a heterogeneous catalyst for the degradation of organophosphorus compounds such as VX agent or sarin. However, the reaction mechanism of the phosphatase mimetic activity of CeO2 nanoparticles is not fully described. Adsorption, surface-promoted hydrolysis, and desorption cycles strongly depend on the physico-chemical characteristics of the facets. In this study, CeO2 nanoparticles with different shapes were elaborated by hydrothermal synthesis. Nano-octahedra, nanocubes, or nanorods were selectively obtained under different conditions (temperature, concentration and nature of the precursors). The degradation activity according to the crystal faces was evaluated in vitro by measuring the degradation kinetics of paraoxon organophosphate in the presence of CeO2 nanoparticles. The results show an influence of both specific surface area and crystal faces of the nanoparticles, with higher activity for {111} facets compared to {100} facets at 32 °C. The relative activity between the facets is ascribed to the adsorption probability, assuming coordination between the phosphoryl oxygen and cerium atoms, but also to the surface density of the Ce doublets with relevant spacing for phosphatase mimetic activity.

Model-based optimization of parameters for degradation reaction of an organophosphorus pesticide, paraoxon, using CeO2 nanoparticles in water media.

Degradation and body surface decontamination is vital to prevent the skin penetration of paraoxon (POX), an organophosphorus pesticide, and victims poisoning. CeO2 demonstrated a good efficacy for the degradation of POX. The aim of the study was to develop a model which includes the impact of weight of CeO2, POX and diluent volumes on the degradation kinetics. The modelling was realized with rapid and simple experiments carried out in tubes, in aqueous diluent which contained ions in order to be in accordance with in vitro skin decontamination conditions. CeO2 had degraded from 5% (in case of 7.5mmol of POX per gram of CeO2) to 100% (0.002mmol of POX per gram of CeO2) of POX. Different kinetic models were tested. Using the particle aggregation kinetic model, the simulated and experimental data were in a good accordance. It highlighted the importance of particles aggregation due to salts and consistency of the mix on the degradation efficiency of CeO2. The model worked also really well to predict the degradation efficiency of CeO2 powders during in vitro skin experiments. However, it did not correctly forecast with an aqueous decontaminant, containing CeO2.