Preparation of porous glass from waste TV panel glasses
Juan Carlos Rendón-Angeles2,
Preparation of porous glass materials occurred employing compacted glass particles by
the Hydrothermal hot-pressing technique, the particles consisted on analogue TV
panel glass (Philips Television, Mexico). The glass TV panel was pulverized then
a sample of 5g with particle size (<38 μm) was mixed with different amounts of
the selected solvents (5 - 20 wt %) water and
Two different concentrations of the
solutions (0.1 and 0.5 M) were used as
foaming agent. The mixture was treated under hydrothermal hot pressing conditions
at a temperature of 200o
C for 2 h, with a constant loading pressure of 20 MPa.
Subsequently, the compacts were conventionally heated at 700°C for 1 h in air.
The TV glass panel particles were markedly dissolved with all the solvents employed,
the glass dissolution was controlled by the amount of the aqueous solution mixed to the
glass powder during the densification stage. The reaction between glass particles with
the solvents selected, water and
solutions; produced a new solid glass phase
incorporating water molecules and Na+
ions, respectively. After heating the
compacts, a marked expansion of the glass compacts occurred. The expansion of HHP
compacted TV-panel glass specimens was further increased on the samples prepared
solution with a concentration of 0.5 M,
the foamed glasses exhibited a
low apparent densities varying between 0.309 - 0.319 g/cm3.
The figure corresponds to the apparent density of the compacted porous glass materials.
Moreover, an important consideration in this particular type of glass is that the
densification of the TV panel glass particles was greatly influenced by the content
of the alkaline solvent, due to the presence of alkaline ions such as
in the raw waste glass composition coupled with the
incorporated with the solvent solution, this chemical interaction promoted the partial
dissolution of the glass particles during the compaction process.
Thus, the large content
of alkaline elements might slightly decrease the softening temperature of the new glass
phase, and the decomposition of these phase produces the formation of both water vapor
gas, the formation of these gases must achieve the increase
of the internal
pressure inside the soften glass bubbles, resulting on a remarkable expansion of the
pseudo-spherical pores, in consequence this process produced the maximum expansion
with the lowest apparent density for the foamed specimens.
1 Technological Institute of Saltillo, Research and Graduate Division, Saltillo 25280, México.
2 Research Institute for Advanced Studies of the NPI, Campus Saltillo, Saltillo 25900, México.
3 Research Laboratory of Hydrothermal Chemistry, Faculty of Science, Kochi University, Kochi 780-8520, Japan