核心提示：近日，yl7703永利晏水平教授課題組研究成果發表，研究提出了基于甘氨酸循環的粉煤灰礦化CO2制備球霰石型CaCO3的新機制，為堿性固廢增值化利用提供了新思路，助力固廢資源化及“雙碳目标”的達成。

南湖新聞網訊（通訊員 鄭璇）近日，yl7703永利晏水平教授課題組研究成果以“Glycine-mediated leaching-mineralization cycle for CO2 sequestration and CaCO3 production from coal fly ash: Dual functions of glycine as a proton donor and receptor”為題在Chemical Engineering Journal發表。

研究提出了基于甘氨酸循環的粉煤灰礦化CO2制備球霰石型CaCO3的新機制，系統闡釋了氨基酸對堿性固廢中堿土金屬離子浸提、CO2高效吸收和球霰石型碳酸鈣定向調控的三重增效機制，利用氨基酸得失質子及絡合特性，通過創新性的反應路徑設計和精确的反應條件控制，實現粉煤灰高效浸出-CO2礦化、CaCO3晶型形貌定向調控、以及氨基酸原位再生，為堿性固廢增值化利用提供了新思路，助力固廢資源化及“雙碳目标”的達成。

基于甘氨酸循環的粉煤灰浸提-CO2礦化（LMC）新機制示意圖

基于堿性固廢的CO2礦化技術是一種減廢降碳協同增效技術，不僅可降低電廠碳排放，還可促進粉煤灰資源化利用。現有直接法粉煤灰CO2礦化工藝雖然過程相對簡單、處理量更大，但是存在反應速率低和産品價值低等問題。間接法CO2礦化工藝過程相對複雜，能聯産高附加值的高純CaCO3産品，具有更好的發展前景。但間接法礦化工藝存在浸出效率較低、礦化過程CaCO3産率和CO2去除率較低、浸出劑難以再生、浸出劑循環性能衰減過快等問題有待解決。

基于甘氨酸循環的粉煤灰浸提-CO2礦化（LMC）可行性探究

針對上述問題，研究提出利用可循環的甘氨酸溶液為浸提劑，在溫和條件下對高鈣粉煤灰中的鈣基組分進行高效浸提，形成的浸提液作為一種良好的CO2吸收劑，可實現CO2脫除并制備高純球霰石型CaCO3，同時還實現甘氨酸的原位再生。

研究表明，在溫和的操作條件下，利用甘氨酸溶液，粉煤灰中Ca2+浸出率為42%，CaCO3産率為89 g/kg-粉煤灰。X射線衍射和掃描電鏡分析表明，CaCO3産品的礦物相以球霰石為主。機理探讨表明，甘氨酸在該工藝中起着多重作用：（1）在浸提過程中，甘氨酸起到質子供體和螯合劑的作用，促進了堿土金屬離子的浸出，提高了堿性礦物相的浸提容量；（2）在礦化過程中，甘氨酸起到質子受體的作用，利用其氨基官能團對CO2的親和性提升CO2吸收速率，利用羧基官能團對CaCO3生長的調控特性定向誘導球霰石型CaCO3的形成；（3）在多重浸提-礦化循環過程，利用其兩性離子可得失溶液質子的特性提供pH緩沖性能，從而實現反應過程效率的提升。五次浸出-礦化循環的試驗結果表明，氨甘氨酸溶液的浸出能力、CaCO3産量和甘氨酸損失相近，驗證了該工藝的穩定性。

我校yl7703永利博士生鄭璇為論文的第一作者，紀龍副教授和晏水平教授為論文共同通訊作者。該研究得到了國家自然科學基金、湖北省自然科學基金、中央高校基本業務經費等項目資助。

【英文摘要】

The state-of-the-art CO2 mineralization technologies involved Ca/Mg leaching and ensued mineralization still struggle with the slow reaction kinetics and frequent pH swings assisted by exogenous chemicals consumption (i.e., low pH for Ca/Mg leaching but high pH for CO2 dissolution and solid carbonates precipitation). This study proposed a glycine-mediated leaching-mineralization cycle (LMC) process, which can simultaneously achieve promising Ca/Mg leaching efficiency, high mineral carbonation efficiency, and production of high-purity CaCO3 from coal fly ash (CFA) at mild operating conditions in an in-situ recyclable amino acid solution. The technical feasibility of the process was initially investigated in individual leaching and mineral carbonation experiments in glycine (Gly0) solutions using a typical CFA. A Ca2+ leaching efficiency of 42.17% and a CaCO3 yield of 89.10 g/kg were achieved in the Gly0 solution. Mineralogy and morphology analysis revealed that the CaCO3 obtained after the carbonation reaction was mainly present as vaterite. The mechanism exploration revealed that Gly-species acted as a proton donor and chelating agent in the leaching step which enhanced the Ca2+ leaching, a proton receptor in mineralization step which accelerated CO2 mass transfer, and a crystal regulator in carbonates precipitation. In addition, the cyclic performance of the LMC process was investigated in multicycle leaching-carbonation experiments. Results showed that the leaching capacities, CaCO3 yield, and Gly0 loss were similar in five cycles of LMC experiments, verifying that the process is stable.

論文鍊接：https://www.sciencedirect.com/science/article/pii/S1385894722013985

來源：南湖新聞