Erik Bonjour’s research while affiliated with Claude Bernard University Lyon 1 and other places

The Asian tiger mosquito Aedes albopictus is well adapted to urban environments and takes advantage of the artificial containers that proliferate in anthropized landscapes. Little is known about the physicochemical, pollutant and microbiota compositions of Ae. albopictus-colonized aquatic habitats and whether these properties differ with noncolonized habitats. We specifically addressed this question in French community gardens by investigating whether pollution gradients (characterized either by water physicochemical properties combined with pollution variables or by the presence of organic molecules in water) influence water microbial composition and then the presence/absence of Ae. albopictus mosquitoes. Interestingly, we showed that the physicochemical and microbial compositions of noncolonized and colonized waters did not significantly differ, with the exception of N2O and CH4 concentrations, which were higher in noncolonized water samples. Moreover, the microbial composition of larval habitats covaried differentially along the pollution gradients according to colonization status. This study opens new avenues on the impact of pollution on mosquito habitats in urban areas and raises questions on the influence of biotic and abiotic interactions on adult life history traits and their ability to transmit pathogens to humans.

The involvement of meteoric water in orogens dynamics through surface processes is well known as for example in the Himalayas where erosion, resulting of the interplay between climate and tectonics shapes the most spectacular landscapes on the planet. But what about more internal and deepest surface fluid infiltration? Here we report analysis of the δ 18 O (water) and δD (water) of extracted water from fluid inclusions hosted into Cenozoic quartz veins sampled in the core of the Himalayan range, near the Main Central Thrust and the South Tibetan Detachment. Isotopic and microthermometric values suggest a meteoric origin for the fluids trapped in the quartz of syn-to post-kinematic veins formed between 10 to 20 km depth. Moreover, the isotopic compositions obtained in this study on quartz fluid inclusions water collected along a transect across the Himalayan range evolved with the topography in a similar manner than the modern meteoric water. Considering the age of formation of the quartz veins between 18 and 12 Ma, we deduce that the morphology of the Himalayan topographic front was already shaped during the Miocene but located further north.

This study focuses on the valorization of biomass waste from the fragrance industry in Provence, France. Adsorbents enriched with oxygen surface groups were produced from Lavandin (Lavandula genus) using the hydrothermal carbonization (HTC) process followed by further NaOH surface treatment. The original Lavandin hydrochar (LH) and NaOH surface treated Lavandin hydrochar (NaOH-LH) were systematically characterized by SEM, FTIR, elemental analysis, zeta potential, and Boehm titration. Specifically, the NaOH surface treatment scavenged the heterogeneous fragments adhering to the surface, increased the number of oxygen surface groups and optimized the ratio of these groups without damaging the hydrochar skeleton structure. Batch adsorption tests for the representative contaminant methylene blue (MB) showed that the adsorption process can be well described by the pseudo-second-order kinetic model and the Langmuir thermodynamic model. In neutral aqueous solution, the three tested adsorbents LH, 0.1%NaOH-LH, and 4%NaOH-LH had adsorption capacities of 52 mg·g⁻¹, 137 mg·g⁻¹, and 306 mg·g⁻¹ for MB. Adsorption experiments allowed us to elucidate that the adsorption mechanism was dominated by electrostatic attractions, supplemented by hydrogen bonds, π-π interactions, and n-π interactions. At some conditions, these capacities overcame the surface density of available adsorption sites, which was attributed to the steric hindrance between stacked adsorbed MB molecules, as the main mechanism governing the maximal surface density of the adsorbed monolayer. This study proves that the combination of the HTC process with NaOH surface treatment method converts Lavandin biomass waste into an efficient adsorbent for MB, providing an economic and ecological alternative for its valorization.

The aim of this work was to investigate the use of biorefinery industry by-products such as humins as adsorbents for methylene blue (MB). After thermal treatment, these by-products are called biochars. Three biochars were used as adsorbents for MB removal: (i) a biochar obtained after thermal treatment of humins (called raw biochar), (ii) a biochar obtained after NaOH treatment of the biochar from (i) (called biochar-OH), (iii) a biochar obtained after mixing humins with lignin, this mixture being then submitted to the same thermal treatment than (i) (called humins-lignin biochar). Structural characterization was done using ATR-FTIR, BET surface area analysis, and scanning electron microscopy (SEM). An elemental analysis was conducted to determine C, H, N, S, and O content in samples. Adsorption experiments were carried out as a function of time, pH, different background electrolytes (NaNO3 and CaCl2), and initial MB concentration. Kinetics data showed a good compatibility of all adsorbents with the pseudo-second-order model. The affinity of MB for biochar increased noticeably with the increase in pH, particularly for biochar-OH and humins-lignin biochar. Both the NaNO3 and CaCl2 background electrolytes had a negative effect on adsorption processes, and Ca²⁺ and Na⁺ acted as competitor ions with MB on the surface. The Langmuir model was more suitable for biochar-OH and humins-lignin biochar, whereas neither the Langmuir nor the Freundlich isotherms fitted experimental results for raw biochar due to its very low adsorption capacity. The maximum adsorption capacity predicted by the Langmuir model allowed us to establish the following classification of biochars: biochar-OH > humins-lignin biochar > > > raw biochar. Modifications of the surface had a positive impact on the adsorption capacity due to the additional available functional groups incorporated into the surface through lignin enrichment and the clean-up of blocked pores through NaOH treatment. Furthermore, formation of macropores on biochar-OH through the NaOH treatment created additional adsorption sites and probably promoted the adsorption of MB via a pore-filling mechanism.

Hydrochars obtained by hydrothermal carbonization (HTC) of Lavandula straws have been studied as an eco-friendly and economical valorization route of residual biomass from cosmetic industry into solid fuels. HTC process has been performed in a temperature range from 180 to 260 °C and retention time ranging from 1 to 20 h. The two key parameters (time and temperature) were normalized to severity factor (SF) ranging from 4.74 to 7.79, in order to compare the fuel characteristics of hydrochars according to the thermal treatment conditions. Proximate and ultimate analysis and microscopy and thermal analysis were used to characterize hydrochar surface, combustion behavior, and kinetics as a function of SF, and to compare them with those of the raw lavandin sample. Results showed that after HTC, hydrochar properties were close to sub-bituminous coal and lignite, and SF was a relevant optimization parameter for solid fuel application. In the case of Lavandula, SF = 6 was the optimal value for the HTC process. Nevertheless, in addition to SF, it is important to consider that HTC-temperature is a more influencing parameter than HTC-retention time for the fuel properties of the resulting hydrochars.

Bulk (Mo2N) and supported molybdenum nitride (Mo2N/TiO2, Mo2N/CeO2) were synthesized by reduction-nitridation of bulk and supported MoO3 under a mixture of N2/H2. We investigated the mechanism of formation of molybdenum nitrides by coupling elemental analysis, in situ and ex situ XRD, Raman spectroscopy, in situ XPS/UPS spectroscopy and DFT calculation. We showed that it is possible to control the crystallographic phase and degree of nitridation (i.e. nitrogen vacancies) by adjusting the parameters of the synthesis, including the heating rate and final temperature, the nature, composition and flow of gas during reduction/nitridation and cooling. We demonstrated that β-Mo2N and γ-Mo2N go through the same intermediates: molybdenum bronze, MoO2 and Mo. The final crystallographic phase of the nitride depends mainly on the temperature rate and gas hourly space velocity employed during the synthesis, as they impact the crystallite size of the intermediates and the kinetics of reduction and nitridation. Molybdenum nitride clusters (< 0.5 nm) are formed on TiO2.

Lavandin hydrochars obtained by hydrothermal carbonization (HTC) of Lavandula distilled straw (LDS) have been studied as an eco-friendly and economical valorization route of residual biomass from cosmetic industry into solid fuels. The critical parameters of the HTC process (temperature and retention time) were normalized to severity factor (SF). Proximate and ultimate analysis, microscopy and thermal analysis were used to characterize hydrochars surface, combustion behavior and kinetics as a function of SF, and to compare them with those of the raw lavandin sample. Results showed that preparation of lavandin hydrochars in temperature and retention time conditions providing SF close to 6 seemed to be the best compromise since under these conditions, the combustion performance of the hydrochar was close to the bituminous coal and lignite.

Parts made by metal additive manufacturing processes assisted by sintering suffer from embrittlement due to binder/powders interactions. Using a core-shell approach, we modelled the diffusion of carbon and oxygen from the binder into the metallic powders. The model was assessed by measuring the interstitials content upon various debinding/sintering steps. The diffusion/precipitation phenomena during these non-isothermal treatments lead to either a saturated solid solution or the precipitation of titanium carbides. The consequences on the mechanical behavior of single 3D printed filaments were quantified by bending tests, highlighting a transition from brittle to ductile fracture depending on the debinding parameters. This approach can be applied to understand the role of fast diffusing interstitial elements into various powders systems in order to optimise the chemical composition and the mechanical properties of 3D printed metallic parts.