Hu Jun, Pincus Lauren N, Wierzbicki Dominik, Du Yonghua, Peters Catherine A
Department of Civil and Environmental Engineering, Princeton University, Princeton, New Jersey 08544, United States.
National Synchrotron Light Source II, Brookhaven National Lab, Upton, New York 11973, United States.
Environ Sci Technol. 2025 Apr 15;59(14):7366-7376. doi: 10.1021/acs.est.5c01640. Epub 2025 Apr 3.
Sulfate wastes are produced in large quantities and contain toxic heavy metals such as lead (Pb), posing environmental risks. Because of favorable solubility differences, these wastes can be repurposed for engineered carbon dioxide (CO) sequestration. Understanding the fate and mobility of heavy metals during this process is important. This study focuses on Pb and the effect of zinc (Zn) on Pb in carbon mineralization. Synthesized gypsum was treated with a carbonate-rich solution at pH 11.5 to convert the sulfates to carbonates. Aqueous solutions and mineral solids were analyzed. Synchrotron-based micro-X-ray fluorescence and a novel application of Pb M3-edge X-ray absorption near-edge structure provided detailed insights into Pb distribution and mineral forms. Results showed significant reductions in aqueous Pb and Zn concentrations, indicating effective metal sequestration. Carbon mineralization transformed Pb from soluble anglesite (PbSO) into insoluble cerussite (PbCO) and hydrocerussite (Pb(CO)(OH)). Pb primarily precipitated onto calcium carbonate surfaces through surface-mediated precipitation reactions. While the presence of Zn modified crystallization dynamics, it did not impede Pb sequestration and potentially enhanced surface reactivity, facilitating greater Pb immobilization. These findings highlight carbon mineralization as a sustainable approach to immobilize toxic metals in sulfate wastes while advancing CO sequestration efforts.
大量的硫酸盐废物被产生，并且含有铅（Pb）等有毒重金属，带来环境风险。由于有利的溶解度差异，这些废物可被重新用于工程化二氧化碳（CO）封存。了解在此过程中重金属的归宿和迁移性很重要。本研究聚焦于铅以及锌（Zn）在碳矿化过程中对铅的影响。合成石膏用pH值为11.5的富含碳酸盐的溶液处理，将硫酸盐转化为碳酸盐。对水溶液和矿物固体进行了分析。基于同步加速器的微X射线荧光以及铅M3边缘X射线吸收近边结构的一种新应用提供了关于铅分布和矿物形态的详细见解。结果显示水溶液中铅和锌的浓度显著降低，表明有效的金属封存。碳矿化将铅从可溶的白铅矿（PbSO）转化为不溶的白铅矿（PbCO）和羟铅矿（Pb(CO)(OH)）。铅主要通过表面介导的沉淀反应沉淀到碳酸钙表面。虽然锌的存在改变了结晶动力学，但它并未阻碍铅的封存，并且可能增强了表面反应性，促进了更大程度的铅固定。这些发现突出了碳矿化作为一种可持续方法，既能固定硫酸盐废物中的有毒金属，又能推进二氧化碳封存工作。
