Soda-lime Borosilicate Glass Research Articles

Influence of zirconium on the structure of pristine and leached soda-lime borosilicate glasses: Towards a quantitative approach by 17O MQMAS NMR

17O MQMAS NMR was used to characterize the influence of zirconium on the structural organization of soda-lime borosilicate glasses. A new method of quantitative analysis of the 17O MQMAS spectra is presented, by a direct fit of the two-dimensional MQMAS spectrum which provides the resolution of all the structural groups in glasses containing up to five oxides. Additional data were also obtained from the quantitative deconvolution of the 11B MAS NMR spectra, with the help of the direct fit of MQMAS data as well. Excess of non-bridging oxygen is clearly identified in these glasses. Sixfolded zirconium is preferentially compensated rather than the tetrahedral boron and calcium only partially compensate the tetrahedral boron. Alteration gels arising from glass leaching were probed by oxygen-17 supplied by the alteration solution. Most of the zirconium is inserted in the silicate network forming Si–O–Zr bonds with the same configuration in the glass and in the gel. During leaching, calcium clearly remains in the alteration gel, either near non-bridging oxygen or as a zirconium charge compensator. This quantitative approach applied to 17O MQMAS spectra demonstrates its potential for investigating the structure of increasingly complex glass and gel compositions.

Incorporation of Galvanic Waste (Cr, Ni, Cu, Zn, Pb) in a Soda–Lime–Borosilicate Glass

In the present investigation, a glassing process for galvanic waste (GW) incorporation with a high chemical stability is presented. Glasses with up to 50 wt% of galvanic solid waste by modifications in the basic composition of soda–lime–borosilicate glasses were prepared. After fusing at temperatures up to 1300°C, the glasses were characterized by inductively coupled plasma, scanning electron microscopy/energy‐dispersive X‐ray spectroscopy, high‐temperature microscopy, transmission and reflected light microscopy, nuclear magnetic resonance, X‐ray photoelectron spectroscopy, and X‐ray diffraction methods. The chemical stability was evaluated by hydrolytic attack assays. Glasses containing up to 40 wt% of GW with a very high chemical stability, similar to bottle glasses, were obtained.

Extraction of heavy metal ions from waste colored glass through phase separation

A new method utilizing phase separation phenomena for the extraction of heavy metal ions used as colorants in colored glass is proposed. Colored soda-lime–silica glass containing Co or Cr as a colorant was remelted with B 2O 3 to yield soda-lime–borosilicate glass. The soda-lime–borosilicate glass thus obtained was leached in 1 M nitric acid at 90 °C to dissolve the borate phase. All cations (Na, Ca, Cr and Co) concentrated in the borate phase are successfully leached out with the dissolution of the borate phase, when the amount of the B 2O 3 added to the glass and heat treatment conditions are properly chosen. Porous silicate glass powders with high SiO 2 purity are obtained as the result of the leaching. Porous glass can also be formed as bulk material by controlling the composition of additives during the remelting.

Enthalpies of Chromium Oxide Solution in Soda Lime Borosilicate Glass Systems

Chromium oxide (Cr2O3) solubility was measured in soda lime borosilicate glass from 1400 to 1500 K. The temperature dependence of the solubility increased with increased sodium oxide concentration. The enthalpies of solution for the equilibrium phases were calculated from the solubility data in the temperature range from 1400 to 1500 K. The enthalpy of fusion for Cr2O3 at 1450 K was calculated to be 108.0 kJ·mol−1. This value was less than our measured values for enthalpy of solution, 111.0 ± 0.5 and 158.4 ± 0.3 kJ·mol−1, indicating that all enthalpies of mixing were positive; that is, the mixing process was endothermic. This characterized the interaction between solute and solvent as repulsive.