Hydrothermal Dissolution of Technical Grade Vitreous Silica in NaOH Solutions to Liquid Water Glasses with Higher SiO 2 :Na 2 O Ratios

Technical grade vitreous silica was dissolved hydrothermally in NaOH lyes. Liquid sodium water glasses with silica concentrations of up to 26.4 wt % and molar SiO 2 :Na 2 O ratios of up to 3.5 were obtained. The dissolution behavior showed two temperature regimes: up to 130 °C the SiO 2 content appr...

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Bibliographic Details
Published in:Chemie ingenieur technik 2021-03, Vol.93 (3), p.473-481
Main Authors: Pfeiffer, Thomas, Enke, Dirk, Roggendorf, Hans
Format: Article
Language:English
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Summary:Technical grade vitreous silica was dissolved hydrothermally in NaOH lyes. Liquid sodium water glasses with silica concentrations of up to 26.4 wt % and molar SiO 2 :Na 2 O ratios of up to 3.5 were obtained. The dissolution behavior showed two temperature regimes: up to 130 °C the SiO 2 content approached a final solubility limit controlled by cristobalite crystallization. Above 130 °C, crystallization of low quartz restricted solubility. The dissolution kinetics were governed by surface area reduction and saturation control according to the Noyce‐Whitney law.
ISSN:0009-286X
1522-2640
DOI:10.1002/cite.202000107