Surface and porous textural properties of silica–wollastonite composites prepared by sol–gel process

• Published in: Journal of sol-gel science and technology 2019-04, Vol.90 (1), p.113-125
• Main Authors: Larreal de Hernandez, Lismarihen, Anez-Borges, Liz, Woignier, Thierry, Hafidi Alaoui, Adil, Calas-Etienne, Sylvie, Despetis, Florence, Bonnet, Laurent, Colaiocco, Bruno, Tahir, Saïd, Dieudonné-George, Philippe
• Format: Article
• Language: English
• Subjects: Carbon sequestration; Carbonation; Ceramics; Chemical Sciences; Chemistry and Materials Science; Composite materials; Composites; Drying; Fillers; Gels; Glass; Inorganic Chemistry; Ludox (trademark); Macroporosity; Material chemistry; Materials Science; Multilayers; Nanotechnology; Natural Materials; Optical and Electronic Materials; Original Paper: Sol–gel and hybrid materials with surface modification for applications; Porous materials; Precursors; Silica gel; Silicon dioxide; Sol-gel processes; Wollastonite
• ISSN: 0928-0707; 1573-4846
• DOI: 10.1007/s10971-018-4874-9

Silica–wollastonite xerogel composites (xerocomposites) with different wollastonite filler content were obtained after classical drying of silica–wollastonite gels. Two different silica precursors were used, TEOS and colloidal LUDOX, for composites named TW and LW, respectively. We utilized SAXS experiments, N 2 adsorption–desorption, and SEM techniques to determine the textural and structural properties of these porous materials. For both the TW and LW composites, it was shown that a macroporosity and a mesoporosity coexist. We argue that the proportion of macroporosity directly depends on the proportion of wollastonite fillers in the composite. We propose a unique two-stage drying mechanism to explain the formation of macropores. We additionally found that the surface of wollastonite fillers was covered by a dense multilayer packing of silica colloids in LUDOX LW xerocomposites. We believe that these surface-modified wollastonite fillers could improve the carbonation kinetics of wollastonite when used as a precursor for aqueous mineral carbonation, a promising route for safe and durable carbon sequestration. SEM image of wollastonite fillers covered by silica in a LUDOX–wollastonite composite (left), and schematic representation of the dense coating of colloidal silica particles at the surface of wollastonite fillers in LUDOX–wollastonite composites (right) Highlights Silica–wollastonite xerogel-composites (xerocomposites) were prepared. TEOS–wollastonite and LUDOX–wollastonite xerogels show porosity at two different scales, a macroporosity and a mesoporosity as confirmed from macroscopic and N 2 adsorption–desorption measurements. SAXS, SEM, and N 2 adsorption–desorption measurements reveal that the wollastonite filler surface is covered by a dense coating of silica colloidal particles in LUDOX–wollastonite xerocomposites.