Investigation of mixed ionic/nonionic building blocks for the dual templating of macro-mesoporous silica.

Traditional porous monoliths Si(HIPE) (High Internal Phase Emulsion), prepared from the Tetradecyltrimethylammonium Bromide (TTAB)/dodecane/water system, offer high specific surface area, mainly due to microporosity. Aside, mesoporous materials SBA-15, prepared from Pluronic P123, have a high specific surface area, but are obtained as powder, which limits their applications. Starting from the mixed TTAB-P123 surfactant, it is expected to tune the mesoporosity of Si(HIPE), while keeping their monolithic character. The ternary TTAB/P123/water phase diagram was established by varying the weight ratio between these two surfactants. The micellar structure as well as the structural parameters of the liquid crystal domains were determined by SAXS (Small Angle X-ray Scattering). The effect of dodecane solubilization was also investigated and concentrated emulsions were formulated from the (P123/TTAB)/dodecane/water systems. After this soft matter dedicated study, the acquired knowledge was transferred toward the hierarchical porous silica generations, where the sol-gel process is involved. Mixing P123 with TTAB, macro-mesoporous monolithic silica with an enhanced contribution of the specific surface area due to mesoporosity can be prepared. The variation of the TTAB/P123 weight ratio allows controlling the porosity at the mesoscale. Moreover, the macroporosity can be tuned by changing the preparation method, by mixing either the two micellar solutions or directly the two surfactants prior the emulsification process.

Bilirubin oxidase-based silica macrocellular robust catalyst for on line dyes degradation.

We present a new heterogeneous biocatalyst based on the grafting of Bilirubin Oxidase from Bacillus pumilus into macrocellular Si(HIPE) materials dedicated to water treatment. Due to the host intrinsic high porosity and monolithic character, on-line catalytic process is reached. We thus used this biocatalyst toward uni-axial flux decolorizations of Congo Red and Remazol Brilliant Blue (RBBR) at two different pH (4 and 8.2), both in presence or absence of redox mediator. In absence of redox mediators, 40% decolorization efficiency was reached within 24 h at pH 4 for Congo Red and 80% for RBBR at pH 8.2 in 24 h. In presence of 10µM ABTS, it respectively attained 100% efficiency after 2h and 12h. We have also demonstrated that non-toxic species were generated upon dyes decolorization. These results show that unlike laccases, this new biocatalyst exhibits excellent decolorization properties over a wide range of pH. Beyond, this enzymatic-based heterogeneous catalyst can be reused during two months being simply stored at room temperature while maintaining its decolorization efficiency. This study shows that this biocatalyst is a promising and robust candidate toward wastewater treatments, both in acidic and alkaline conditions where in the latter efficient decolorization strategies were still missing.

Inorganic, Hybridized and Living Macrocellular Foams: "Out of the Box" Heterogeneous Catalysis.

With this personal account we show how the Integrative Chemistry, when combining the sol-gel process and concentrated emulsions, allows to trigger inorganic, hybrid or living materials when dedicated toward heterogeneous catalysis applications. In here we focus on 3D-macrocellular monolithic foams bearing hierarchical porosities and applications thereof toward heterogeneous catalysis where both activities and mass transport are enhanced. We thereby first depict the general background of emulsions, focusing on concentrated ones, acting as soft templates for the design of solid (HIPE) foams, HIPE being the acronym for High Internal Phase Emulsions while encompassing both sol-gel and polymer chemistry. Secondly we extend this approach toward the design of inorganic cellular materials labeled Si(HIPE) and hybrid organic-inorganic foams, labeled Organo-Si(HIPE), where heterogeneous catalysis applications are addressed considering acidic, metallic, enzymatic and bacterial-based modified Si-HIPE. Along, we will show how the fluid hydrodynamic within the macrocellular foams is offering advanced "out of the box" heterogeneous catalytic capabilities.