Jérémy Causse

Facile one-pot synthesis of copper hexacyanoferrate nanoparticle functionalised silica monoliths for the selective entrapment of 137Cs

In this study, hexacyanoferrate nanoparticle (NP) functionalised silica monoliths were used to selectively remove Cs+ from aqueous solutions which also contained large concentrations of Na+. Various NP loading levels were examined from 0.2 wt% up to 5.1 wt% producing different 133Cs and 137Cs sorption results.

Effect of aging and alkali activator on the porous structure of a geopolymer

Nitrogen sorption and small- and wide-angle X-ray and neutron scattering techniques were used to study the porous structure of geopolymers, inorganic polymers synthesized by reaction of a strongly alkaline solution and an aluminosilicate source (metakaolin). The effects of aging and the use of alkali activators (Na+, K+) of different sizes were investigated at room temperature. The influence of aging time on the microstructure of both geopolymer matrixes was verified in terms of pore volume and specific surface area. The results suggested a refinement of the porosity and therefore a reduction in the pore volume over time. Regardless of the age considered, some characteristics of the porous network such as pore size, shape and distribution depend on the alkali activator used. Whatever the technique considered, the potassium geopolymer has a greater specific surface area than the sodium geopolymer. According to the scattering results, the refinement of the porosity can be associated with, first, a densification of the solid network and, secondly, a partial closure of the porosity at the nanometre scale. The kinetics are much slower for the sodium geopolymer than for the potassium geopolymer in the six months of observation.

Effect of the chemical nature of different transition metal ferrocyanides to entrap Cs

Transition metal ferrocyanides are used since many years to selectively entrap radio-cesium from nuclear contaminated effluents. We investigate the cesium sorption properties on a series of ferrocyanides containing different transition metal ions (Ni2+, Co2+ and Cu2+) and outline the role of the chemical nature of the bivalent metal ion, the iron oxidation state, the presence of K+ in the structure and the grain size of the powders on the equilibrium time and efficiency of the Cs+ sorption.

Synthesis of poly(diallyldimethylammonium) capped copper hexacyanoferrate (CuHCF) nanoparticles: An efficient stabiliser for Pickering emulsions

Poly(diallyldimethylammonium chloride) (PDDA) capped copper hexacyanoferrate nanoparticles (CuHCF NPs) with the controlled size are prepared following a precipitation method. While PDDA and CuHCF are not active at the cyclohexane/water interface, PDDA capped CuHCF NPs present synergistic property permitting them to stabilise oil-in-water emulsions for weeks. These latter can be considered as promising precursors for the development of new porous materials considering the fact that the NPs present some interests in the field of nuclear decontamination.

Copper hexacyanoferrate functionalized single-walled carbon nanotubes for selective cesium extraction

Single-walled carbon nanotubes (SWCNTs) are functionalized with copper hexacyanoferrate (CuHCF) nanoparticles and therefore constitutes promising solid substrates for the sorption of Cs+ ions from liquid effluents. The high mechanical resistance and large electrical conductivity of SWCNTs are associated to the ability of CuHCF nanoparticles to selectively complex Cs+ ions in order to achieve membrane-like buckypapers presenting high loading capacity of cesium. The materials are thoroughly characterized using electron microscopy, Raman scattering, X-ray photoelectron spectroscopy and thermogravimetric analyses. Cs sorption isotherms are plotted after liquid phase ionic chromatography of the Cs solutions before and after exposure to the materials. It is found that the total sorption capacity of the material reaches 230 mg.g-1, and that one third of the sorbed Cs (80 mg.g-1) is selectively complexed in the CuHCF nanoparticles grafted on SWCNTs. These high values open interesting perspectives in the integration of such materials in electrically driven devices for the controlled sorption and desorption of these ions.