Indirect aqueous carbonation of CaSO₄·2H₂O with aspartic acid as a recyclable additive

Abstract

Aspartic acid was employed as a recyclable additive during the indirect aqueous carbonation of CaSO4·2H2O. The multiple roles of aspartic acid were found to be Ca2+ leaching agent, CO2 absorbent, and CaCO3 polymorph regulator.

Progress in the Preparation of Calcium Carbonate by Indirect Mineralization of Industrial By-Product Gypsum

“…Next, CO 2 was passed through the calcium-rich solution to form calcium carbonate and complete the CO 2 sequestration. Finally, the leaching agent was regenerated and recycled [53][54][55]. The technical process is shown in Figure 2, corresponding to reaction Equations ( 1)-(3).…”

“…Gong et al [55] leached and mineralized CaSO 4 •2H 2 O by exploiting the solubility difference of aspartic acid at different pH values. The results showed that the solubility of CaSO 4 •2H 2 O was 16.3 g L −1 in 7 wt.% ammonia and a liquid-to-solid ratio of 50.…”

“…The regeneration of the leaching agent is also different when the industrial by-product gypsum is indirectly mineralized via complexation. Gong et al [55] combined the dissolution characteristics of amino acids with the leaching-mineralization of desulfurized gypsum. Because amino acids are sparingly soluble at their isoelectric points, aspartic acid can be precipitated and then recycled by adjusting the pH to the isoelectric point after mineralization.…”

A Simplified Model for Shear Behavior of Mortar Using Biomimetic Carbonate Precipitation

“…The interaction between Asp molecules and calcium has been widely investigated from the perspective of surface energy [ 13 ] and kinetics [ 14 ], but the actual mechanism is still not that clear. One generally accepted fact is that there exists a complexation effect between Asp molecules and calcium ions [ 15 ], and some functional groups like -COO - could serve as potential nucleation sites for the crystallization of CaCO 3 [ 16 ]. Recent studies show that Asp may also bind to the precipitated crystals [ 17 ] and affect the morphology, phase, and crystal structure through the additional electrostatic interactions of side-chain groups with mineral surfaces [ 18 ].…”