Characterization and remediation of pollutants in air and water (CARE)

Manager : VERNOUX Philippe
Deputy Manager : GIROIR-FENDLER Anne

1. Measurement and identification of pollutants and their degradation products in the environment and in pollution abatement processes


Although many regulations have been implemented, the pollution of air is still a major problem in urban and suburban areas, with recognized health and climate impacts. Many emissions (gaseous and particulate) and physicochemical transformations in the atmosphere remain clearly ignored, reducing the possibilities for air quality improvement. Emissions from different transportation modes are part of these poorly quantified emissions, as well as the non-regulated emissions from new cars which are not well understood yet. Even less understood is the formation of secondary organic particles produced by photochemical reactions of volatile compounds emitted by combustion engines. CARE will devote expertise and tools to study and develop new knowledge on emissions of gaseous and particulate pollutants (metrology and analysis of aerosols and soots) as well as their behavior and fate in the atmosphere, with a specific attention for reactive oxygenated species and the formation of secondary organic aerosols.

2. Formulation of new materials and process development for the treatment of pollutants in air, water and particulate phase

  • Air treatment

Catalytic materials have to be continuously improved to comply with more stringent standards in terms of emission levels (ambient air, living and working places, environment) and longer operation, but also to anticipate the expected decline in global resources of certain assets such as precious metals. CARE has strong and specific skills to find innovative solutions to crucial problems such as lowering catalyst operating temperature and limiting, or even eliminating, the use of noble metals. The pollutants covered are nitrogen oxides, unburnt hydrocarbons, carbon monoxide, volatile organic compounds (VOCs) and particulate matter. In the field automotive pollution control, the technological key points relate to the integration of the DeNOx system inside the particulate filter and the development of self-regenerating filters.

Electrochemical promotion of catalysis

The specific interactions between an active metallic phase and an ionic conducting support (currently by oxygen ions) and their impact on the catalytic performances are studied. During the last fifteen years, research in the group focused on polarized electrochemical catalysts using thin films of catalyst deposited on a dense ionic conducting support. The electrochemical promotion of numerous reactions, especially oxidations, has been demonstrated and explained by the presence of ionic species at the surface of the metallic films. The scientific key point is to reconcile the electrochemical activation and a high dispersion of the metallic phase. These electro-activated nanoparticles should find new applications, especially in the treatment of soot particulates and the oxidation of unburnt hydrocarbons.

Coupling processes for the reduction of pollutants

(Filtration, catalysis, adsorption, catalysis, catalysis metal thin-film support)

The optimization of catalytic systems also requires  to develop specific shaping that could improve performances under real operating conditions. Important studies have been conducted to couple catalysis to filtration, separation and/or adsorption. Comparisons with conventional methods will be continued in the areas of catalytic membrane reactors, passive samplers and catalyzed filters.

  • Water treatment


The presence of various contaminants at trace levels in ground or surface water often requires the implementation of further treatments upon the production of drinking water. The adsorption process, which is easy to implement and does not require any additional chemical reagents, is certainly the most common treatment. Adsorbents, including activated carbons, must retain very different kinds of pollutants, from micro-pollutants to natural organic substances. The surface properties of the adsorbents may have a major impact on their adsorption properties. Intermittent temperature programmed desorption (ITPD, developed in our Institute) might be reliably used for this kind of study. Moreover, most studies were conducted in a static mode while real applications would most probably be operated in a continuous mode. Specific setups have to be developed to access breakthrough curves.


Air and water might also be contaminated by microbiological agents. Photocatalysis might also be used to eliminate such pollutants at room temperature, using oxygen from the air as the oxidant and UV photons, in particular solar photons. Photocatalytic disinfection is still at the very beginning. Significant efforts must be made to study the interactions between microorganisms and catalyst and also to understand the disinfection mechanisms. New materials have to be developed and compared in different advanced oxidation processes. The impact of these processes on the environment must also be considered.

Wet air oxidation of nitrogen-containing compounds

Catalysts developed until now are very active and stable in the oxidation of organic compounds (C, H, O), but also for the selective conversion of ammonia in aqueous phase into molecular nitrogen. Aromatic amines, such as aniline, may also be efficiently eliminated. However, a very strong leaching of the active metal is observed when a lone pair of electronsr is present and located on the nitrogen atom (aliphatic amines, amino acids). Thus, the use of these catalysts for the treatment of effluents containing such compounds is totally excluded at this stage. The formulation of new catalytic materials which are thermally and chemically stable is absolutely necessary. Combinations of an oxide-type active phase (pure or composite) and a meso-structured carrier are currently considered to enable (i) optimizing the support-metal interactions by a confinement effect of the oxide nanoparticles, (ii) increasing the catalyst-reactant contact area, (iii) improving the transfer of reactants towards the active surface and consequently promoting the catalytic activity

3.Understanding of macro- and micro-kinetic processes, identification of the active sites and study of basic mechanisms involved in catalytic and atmospheric processes.

Identification of the reactive oxygen species

Most processes studied in the group are oxidative treatments. The nature of the most reactive oxygen species is often a matter of debate. However, these issues are of crucial importance for both fundamental understanding and practical applications. The detection and quantification of these species, the nature of which may vary from one process to another, is a real challenge, particularly if one considers the lifetime of these species, or the difficulty to carry out analysis under realistic reaction conditions. The development of new operando tools, involving among other techniques Raman spectroscopy, may be required. The electrochemical promotion of catalysis coupled to chemisorption and isotopic exchange methods is also a useful tool to study the role of lattice oxygens within the catalyst or the catalyst carrier. This technique is particularly relevant because the oxygen ion flow from the ion conductive support towards the surface of the catalyst is controlled by the electrical polarization.

Selective catalytic reduction (SCR) of NO

Catalytic systems developed for the post-treatment of gaseous exhausts must meet stricter and stricter specifications, particularly in terms of efficiency over long time periods. To simulate aging, models have to be developed. To feed these models, kinetic data for all chemical reactions taking place in such a complex environment must be acquired. In this context, the SCR of NO by NH3 will be one of the model reactions selected to develop these macro- and micro-kinetic studies. The impact of the treatments carried out upstream or in parallel (oxidation catalysis of HC, CO, NO, and soot) on the kinetic parameters will be specifically studied.

Chemical processes in the atmosphere

The atmosphere is a complex environment that is far from being homogeneous. Indeed it contains small amounts of condensed matter (liquid or solid) that can influence both the radiative forcing and the chemical composition. The impact on the radiative forcing was the subject of numerous studies (and still is), while the identification of the chemical role of aerosols is much more recent. Indeed, the diversity of the aerosols coupled with the incredible chemical complexity of the troposphere makes new reaction paths possible. CARE activities in the field are connected to the physical chemistry and the heterogeneous (photo)chemistry in the troposphere. A major focus of our research in atmospheric chemistry is to look at the importance of aerosols in the formation of radicals and highly functionalized species (oxygenated) at the interface..