Córdoba Patricia
Institute of Environmental Assessment and Water Research (IDÆA-CSIC), Spanish National Research Council, C/Jordi Girona 18-26, Barcelona 08034, Spain.
ACS Omega. 2024 Aug 7;9(33):35906-35919. doi: 10.1021/acsomega.4c04958. eCollection 2024 Aug 20.
The sequestration of carbon dioxide (CO) stands as a profoundly pivotal environmental challenge, given its potential to directly contribute to the advancement of environmental, societal, and economic objectives across a multitude of nations. In the present study, we have conducted an evaluation of the metal impurity partitioning and speciation in mineral carbonation processes conducted in laboratory using flue gas desulfurization (FGD) gypsums originating from both Spanish and two Chinese coal-fired power plants, each subject to distinct fuel sources and FGD operational conditions. Of the three resultant carbonation products, two exhibited CaCO content in the range of 81-83%, while the third registered 76.9% CaCO content-a variance attributed to the occurrence of metallic impurities within the initial FGD-gypsum. The partitioning and speciation of metal impurities at all stages of CO conversion have enabled us to proffer four potential reaction mechanisms governing carbonation efficiency: (i) conversion of metal sulfates to metal carbonate complexes, (ii) transformation of transferable elements into metal oxides and oxyhydroxide complexes, (iii) transformation of metal sulfates into diverse metal complexes, and (iv) diverse pathways of elemental transformation. Metal impurities present in FGD-gypsum lead to the formation of complexes between As and metals, thereby affecting their activity. Higher Ca/Mn, Ca/Fe, and Ca/Al ratios in one FGD-gypsum slurry enhance Ca(AsO)·8HO activity, while in another, excess Ca facilitates Mn(AsO)·8HO formation during carbonation, with coprecipitation retaining As in carbonation products. The occurrence of metallic contaminants in FGD-gypsums may exert a substantial influence on the effectiveness of CO conversion, thereby impacting the feasibility of using resultant carbonation products, with potential implications for environmental leaching and diminished reusability prospects.
鉴于二氧化碳（CO₂）有可能直接推动众多国家在环境、社会和经济目标方面的进展，其封存是一项极其关键的环境挑战。在本研究中，我们对实验室中使用源自西班牙和两家中国燃煤电厂的烟气脱硫（FGD）石膏进行的矿物碳酸化过程中的金属杂质分配和形态进行了评估，每个电厂都有不同的燃料来源和FGD运行条件。在三种生成的碳酸化产物中，两种的碳酸钙含量在81 - 83%范围内，而第三种的碳酸钙含量为76.9%——这种差异归因于初始FGD石膏中金属杂质的存在。在CO₂转化的各个阶段，金属杂质的分配和形态使我们能够提出四种控制碳酸化效率的潜在反应机制：（i）金属硫酸盐转化为金属碳酸盐络合物，（ii）可转移元素转化为金属氧化物和羟基氧化物络合物，（iii）金属硫酸盐转化为多种金属络合物，以及（iv）元素转化的多种途径。FGD石膏中存在的金属杂质导致砷与金属之间形成络合物，从而影响它们的活性。一种FGD石膏浆液中较高的钙/锰、钙/铁和钙/铝比率增强了Ca₃(AsO₄)₂·8H₂O的活性，而在另一种浆液中，过量的钙在碳酸化过程中促进了Mn₃(AsO₄)₂·8H₂O的形成，共沉淀使砷保留在碳酸化产物中。FGD石膏中金属污染物的存在可能对CO₂转化的有效性产生重大影响，从而影响使用所得碳酸化产物的可行性，对环境浸出和再利用前景降低具有潜在影响。
