Geopolymer foams obtained by the saponification/peroxide/gelcasting combined route using different soap foam precursors

Abstract

This work investigates the influence of eight different vegetable and animal sources of fatty acids as soap foam precursors in the processing of highly porous geopolymers. Four sources rich in saturated chains (coconut and babassu oils, palm stearin and beef tallow), two sources rich in monounsaturated chains (olive and castor oils) and two sources rich in polyunsaturated chains (sunflower oil and soybean biodiesel) were selected. For all soap precursors, bodies treated at 300°C possessed a very high total porosity (84-88 vol%), open porosity (79-85 vol%) and relatively high specific surface area (35.1-63.5 m 2 /g), but rather low compressive strength (0.2-0.4 MPa). The increase in the thermal treatment temperature caused a slight decrease in porosity but a substantial increase in compressive strength and decrease in specific surface area due to sintering and formation of crystalline phases. The Darcian permeability coefficients of all bodies (0.6-10.6910 À10 m 2 ) were typical of gelcasted foams, aerosol filters and fibrous mats.The morphology of pores could be well-associated to the features of lathers produced by the respective soap precursors.

Study on the effect of emulsifiers on the pore structures of geopolymer prepared by emulsion templating

“…The pore structure parameters of geopolymer were obtained from the SEM images using Image-Pro Plus (IPP) software (usually 300∼500 pores were measured per sample), and the effective pore-size (D sphere ) was determined by the stereological equation D sphere =D circle /0.785 according to ASTM D3576-98 [7,19,25], the D circle was defined as the pore size which exported from the IPP software.…”

“…pore size and distribution, can be effectively regulated by changing the types of template and emulsifier [10,15,16]. In recent years, emulsion templating method was introduced into the preparation of porous geopolymers [17][18][19][20]. Template droplets are homogeneously dispersed and stabilized by the aluminosilicate particles with certain hydrophilicity in the geopolymer paste, and Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.…”

Synergistic effect of animal oil or butter and hydrogen peroxide on physical and mechanical properties of porous alumino-siliceous materials

“…A typical representation of fatty acid compositions is C x: y in which x is the number of carbons, y is the number of double bonds. Generally, C 16:0 (Palmitic acid) is the most common saturated fatty acid in animals, plants, and microorganisms, and C 18:1 (Oleic acid) is the most common monounsaturated fatty acid in plants, animals and microorganisms [26].…”

3D structure of oil droplets in hardened geopolymer emulsions

“…Composite materials made of geopolymer (GP) cement and organic liquids (oils) have been proposed recently for the synthesis of porosity‐controlled media, for example, as thermal insulating foams or filtration supports, for the management of radioactive organic liquid waste, and as phase change materials (PCM)…”

“…Another technique has been proposed, which is based on saponification of reactive vegetal oil and peroxide. The obtained porous solids have spherical macropores of 40 to 490 μm size, potentially percolating depending on the amounts of oil and peroxide …”