1. Simultaneous productions of high-purity calcium carbonate and amorphous nanosized silica-rich gel from waste concrete powder by alkaline treatment and carbonation.
- Author
-
Liu L, Ou G, Xu L, Ogiwara N, Uchida S, Yang H, and Sakai Y
- Abstract
Simultaneous productions of high-purity CaCO
3 (calcium carbonate) and amorphous nanosized SiO2 -rich (silica-rich) gel from waste concrete powder remain quite challenging, and thus the high-value added utilization of waste concrete powder is significantly limited. A novel technology involving a combination of alkaline treatment and carbonation, has been proposed for the greatly enhanced utilization of waste concrete powder. Through alkaline treatment, CaCO3 and SiO2 -rich gel formed during carbonation of concrete powder were transformed into Ca(OH)2 (calcium hydroxide) and Na2 SiO3 (sodium metasilicate), respectively. Subsequently, Ca(OH)2 and Na2 SiO3 were separated. As a result, CaCO3 with a high purity of 98.54% and amorphous nanosized SiO2 -rich gel were obtained via carbonation, and the recovery ratio of CaCO3 was 81.46%. Furthermore, the concrete powder exhibited a high CO2 (carbon dioxide) uptake efficiency of 0.24g CO2 /g. 30.31 Mt CaCO3 and 2.77 Mt SiO2 -rich gel productions as well as 38.54 Mt CO2 emission reduction could be realized via recycling a quarter of annually generated waste concrete powder worldwide., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)- Published
- 2024
- Full Text
- View/download PDF