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Research fields

Solid foams derived from tannins

 


These foams are the natural counterparts of commercial phenolic foams, but are ecological, cheap and easily produced. Many formulations have been successfully developed in order to obtain several generations of materials: rigid foams, formaldehyde-free, with controlled porosity, semi-rigid or fully elastic, comprising vegetable proteins or not, etc. They are non flammable and auto extinguishable. Applications are : thermal insulation, shock mitigation, sound absorption, heavy metals adsorption, cores of lightweight sandwich panels, etc. (Figures 2 and 3, video 1).

 

                                   

 

Porous monoliths derived from tannins

 


Porous monoliths having very diverse structures were also obtained, not by foaming but hardening of tannin-based emulsions (polyHIPE). Solvent washing then allowed to create a fully interconnect porosity. Tuning the numerous adjustable parameters of the process leads to a broad family of porous materials. Not using oil is even possible by whipping tannin solutions containing surfactants until stiff, giving rise to extremely light foams. Applications are: phonic insulation, catalysis, chromatography, adsorption, floral foams, etc. (Figures 4 and 5).

 

                   

                                            

 

Cellular carbons derived from tannins

 


These are the pyrolysis products of the aforementioned foams and porous monoliths. They present a high electrical conductivity, an improved mechanical, thermal and chemical resistance, and have a surface which can be chemically modified in order to increase significantly their surface area. Applications are: electrochemistry, electrosorption, heterogeneous catalysis, filtration of corrosive fluids or molten metals, absorption of electromagnetic waves, etc. (Figures 6 and 7).

 

      

 

Organic gels

 


These are chemical or physical (thermoreversible) gels derived from vegetable polyphenols (tannins and lignins), also comprising synthetic molecules (phenol, resorcinol) or proteins. After subcritical, supercritical (in various solvents) or freeze-drying, xerogels, aerogels and cryogels with controlled porosity, respectively, are obtained. Applications are: catalysis, adsorption, thermal insulation, etc. (Figure 8).

                                    

Carbon gels

 


After pyrolysis of the aforementioned gels, highly porous materials having a highly developed surface area are obtained. Applications are: electrochimistry, catalysis, adsorption, high-temperature thermal insulation, etc. (Figures 9 and 10).

                                 

                                 

Activated carbons

 


This topic remains a very important valorisation route of agricultural wastes. The difficulty consists in optimizing the performances of the products for a minimal production cost, each vegetable biomass having its own peculiarities. The idea thus consists in using local under valorised resources and treating them in order to get activated carbons that are adapted to the treatment of local contaminations. Examples are: development of adsorbents of arsenic derived from Mexican agave bagasse for the treatment of groundwater in Mexico ; development of adsorbents of phenols derived from rice straws grown in Nile delta for the treatment of Egyptian waters; development of gas concentrators for miniaturized systems of race detection. (Figures 11 to 13).

                               

Materials for hydrogen storage

 


Chemical activation of natural anthracites allowed obtaining hydrogen storage capacities among the highest ever reported so far in the open literature: 6.6 wt.% at 77K and 4 MPa. Such performances may be improved by doping with heretoelements, metallic or not. Doping is carries out in supercritical or hydrothermal conditions. (Figure 14).

Hydrothermal carbons

 


Hydrothermal treatment of biomass leads to a broad family of porous materials, from monodisperse powders to aggregates and gels. It also allows stabilizing volatile elements in the carbonaceous matrix. Hydrothermal carbonization of polyphenols and chitin in various solvents more or less mineralized gives rise to carbons having original porous texture, enriched in heteroelements. Applications are: adsorption, catalysis, electrochemistry, etc. (Figure 15).

Reaserch Topics

Solid foams derived from tannins

 

These foams are the natural counterparts of commercial phenolic foams, but are ecological, cheap and easily produced. Many formulations have been successfully developed in order to obtain several generations of materials: rigid foams, formaldehyde-free, with controlled porosity, semi-rigid or fully elastic, comprising vegetable proteins or not, etc. They are non flammable and auto extinguishable. Applications are : thermal insulation, shock mitigation, sound absorption, heavy metals adsorption, cores of lightweight sandwich panels, etc.

Porous monoliths derived from tannins

 

Porous monoliths having very diverse structures were also obtained, not by foaming but hardening of tannin-based emulsions (polyHIPE). Solvent washing then allowed to create a fully interconnect porosity. Tuning the numerous adjustable parameters of the process leads to a broad family of porous materials. Not using oil is even possible by whipping tannin solutions containing surfactants until stiff, giving rise to extremely light foams. Applications are: phonic insulation, catalysis, chromatography, adsorption, floral foams, etc.

 

Cellular carbons derived from tannins

 

These are the pyrolysis products of the aforementioned foams and porous monoliths. They present a high electrical conductivity, an improved mechanical, thermal and chemical resistance, and have a surface which can be chemically modified in order to increase significantly their surface area. Applications are: electrochemistry, electrosorption, heterogeneous catalysis, filtration of corrosive fluids or molten metals, absorption of electromagnetic waves, etc.

 

Organic gels

 

These are chemical or physical (thermoreversible) gels derived from vegetable polyphenols (tannins and lignins), also comprising synthetic molecules (phenol, resorcinol) or proteins. After subcritical, supercritical (in various solvents) or freeze-drying, xerogels, aerogels and cryogels with controlled porosity, respectively, are obtained. Applications are: catalysis, adsorption, thermal insulation, etc.

Carbon gels

 

After pyrolysis of the aforementioned gels, highly porous materials having a highly developed surface area are obtained. Applications are: electrochimistry, catalysis, adsorption, high-temperature thermal insulation, etc.

 

 

 

Activated carbons

 

This topic remains a very important valorisation route of agricultural wastes. The difficulty consists in optimizing the performances of the products for a minimal production cost, each vegetable biomass having its own peculiarities. The idea thus consists in using local under valorised resources and treating them in order to get activated carbons that are adapted to the treatment of local contaminations. Examples are: development of adsorbents of arsenic derived from Mexican agave bagasse for the treatment of groundwater in Mexico ; development of adsorbents of phenols derived from rice straws grown in Nile delta for the treatment of Egyptian waters; development of gas concentrators for miniaturized systems of race detection.

Materials for hydrogen storage

 

Chemical activation of natural anthracites allowed obtaining hydrogen storage capacities among the highest ever reported so far in the open literature: 6.6 wt.% at 77K and 4 MPa. Such performances may be improved by doping with heretoelements, metallic or not. Doping is carries out in supercritical or hydrothermal conditions.

Hydrothermal carbons

 

Hydrothermal treatment of biomass leads to a broad family of porous materials, from monodisperse powders to aggregates and gels. It also allows stabilizing volatile elements in the carbonaceous matrix. Hydrothermal carbonization of polyphenols and chitin in various solvents more or less mineralized gives rise to carbons having original porous texture, enriched in heteroelements. Applications are: adsorption, catalysis, electrochemistry, etc