Experimental Study of CO2 Mineralization in Ca2+-Rich Aqueous Solutions Using Tributylamine as an Enhancing Medium

The feasibility of using tributylamine as a pH regulator to enhance CO2 mineralization in Ca2+-rich aqueous solutions was demonstrated. The influencing factors, such as the makeup of the extraction system and the operating parameters, were investigated experimentally. With N-butyl alcohol as the diluent of tributylamine, the mineralization ratio could reach approximately 93% for an initial concentration of 3.4 g/L when the dilution ratio was 2:1 and the ratio of organic to water was 4:1. A stirring speed of 500 rpm was observed to be sufficient to ensure good mixing of organic and water phases. A rise in the reaction temperature results in a lowering of the mineralization ratio. Characterization using X-ray diffraction (XRD) and scanning electron microscopy (SEM) indicated that the precipitation product is pure CaCO3 that is sufficiently good for use in commercial filling agents. Moreover, it was determined that Ca(OH)(2) powder acted as an excellent regenerant to turn N(C4H9)(3). H+ in the organic phase back into tributylamine. The extraction system exhibited stable performance for acting as the enhancing medium for CO2 mineralization reactions in Ca2+-rich aqueous solutions, after 11 rounds of regeneration cycles. The results of this study provide information that is relevant for practical application of this CO2 fixation concept.