Experimental Study of CO2 Mineralization in Ca2+-Rich Aqueous Solutions Using Tributylamine as an Enhancing Medium
2014
Liu, Xin | Wang, Wenlong | Wang, Man | Wang, Peng
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.
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