CO2 Utilization via Direct Aqueous Carbonation of Synthesized Concrete Fines under Atmospheric Pressure.

Hsing-Jung Ho,Takumi Endo,Hisashi Tomita,Atsushi Iizuka,Kenji Takano,Etsuro Shibata

doi:10.1021/acsomega.0c00985

Abstract

Mineral carbonation using alkaline wastes is an attractive approach to CO2 utilization. Owing to the difference between waste CO2 and feedstock CO2, developing CO2 utilization technologies without CO2 purification and pressurization is a promising concept. This study investigated a potential method for CO2 utilization via direct aqueous carbonation of synthesized concrete fines under atmospheric pressure and low CO2 concentration. The carbonation reaction with different solid–liquid ratios and different concentrations of introduced CO2 was examined in detail. Under basic conditions, a CO2 uptake of 0.19 g-CO2/g-concrete fines demonstrated that direct aqueous carbonation of concrete fines under atmospheric pressure and low CO2 concentration is effective. The CaCO3 concentration, degree of carbonation, and reaction mechanism were clarified. Furthermore, characterization of the carbonated products was used to evaluate ways of utilizing the carbonated products.

Highlights

Carbon capture and utilization (CCU) is one potential option for mitigating the problem of CO2 emissions
This study investigated CO2 utilization via mineral carbonation using synthesized concrete fines from an aggregate recycling process under atmospheric pressure, which makes possible the avoidance of the difficulties of CO2 pressurization
The results of the carbonation reaction under basic conditions showed that CO2 uptake was 3.71 g-CO2 and that almost all of the absorbed CO2 was captured as CaCO3 at the reaction starting point

Summary

Introduction

Carbon capture and utilization (CCU) is one potential option for mitigating the problem of CO2 emissions. In the CCU technology, CO2 is regarded as feedstock to be utilized in various applications, which could simultaneously yield economic income and reduce CO2 emissions. With consideration of requirements and situation, several CO2 utilization technologies have been investigated. One of the problems is the difference in CO2 purity and pressure between waste CO2 and feedstock. Most CCU technologies require high-purity and highpressure feedstock CO2, while CO2 purity is

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