Novel low temperature synthesis of sodium silicate and ordered mesoporous silica from incineration bottom ash

JOURNAL OF CLEANER PRODUCTION

卷:211

Article

Alam, Qadeer¹  Hendrix, Yuri¹  Thijs, Luuk¹  Lazaro, Alberto¹  Schollbach, Katrin¹  Brouwers, H. J. H.¹ 

[1] Eindhoven Univ Technol, Dept Built Environm, POB 513, NL-5600 MB Eindhoven, Netherlands

关键词: Water-glass;    Mesoporous silica;    Bottom ash;    Rietveld analysis;    Sodium silicate;    MSWI;   

DOI  :  10.1016/j.jclepro.2018.11.173

来源: Elsevier

【 摘 要 】

A novel low temperature synthesis route to convert environmentally harmful silica-rich waste incineration bottom ashes into ordered mesoporous silica is reported. Bottom ash is a major by-product of municipal solid waste incineration with limited recycling options due to harmful contaminants. In this study, a low temperature alkaline dissolution process was employed to synthesize sodium silicate instead of a conventional high temperature fusion process. Moreover, the dissolution process was systematically investigated to attain fundamental insight into the hydrolysis of silica from bottom ash, which is currently lacking in the existing literature. The mineralogical composition of the ash residues before and after desilication experiments was quantified via Rietveld analysis to understand the formation of byproducts, such as geopolymeric gels and zeolites. These by-products hinder the dissolution of the silica because of the following two factors: Firstly, their formation consumes part of the soluble silicate and, secondly, the precipitation of the by-products around the etching particles of bottom ash act as a passivating layer which hinders the diffusion of soluble silica away from the particle. The optimized reaction temperature and reaction time for the silica extraction was observed to be 75 degrees C for 48 h. A sequential extraction under these conditions can successfully attain an extraction efficiency of 70% of the silica. Subsequently, the sodium silicate derived from the bottom ash was used to synthesize mesoporous silica with a high specific surface area and purity of 870 m(2)/g and 99 wt %, respectively. (C) 2018 Elsevier Ltd. All rights reserved.

【 授权许可】

Free