State Key Laboratory of Clean Energy Utilization, National Engineering Laboratory of Waste Incineration Technology and Equipment, Institute of Thermal Power Engineering of Zhejiang University, Hangzhou, 310027, Zhejiang, China.
MOE Key Laboratory of Environmental Remediation and Ecosystem Health, Institute of Environmental Health, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, 310058, China; Zhejiang Development & Planning Institute, Hangzhou, 310000, China.
Chemosphere. 2022 Feb;288(Pt 2):132420. doi: 10.1016/j.chemosphere.2021.132420. Epub 2021 Sep 30.
Calcium carbonate oligomers are gel-state precursors that can be crystallized by low-temperature heat treatments to form an inorganic material with a monolithic and continuous structure, this material can effectively solidify/stabilize heavy metals in municipal solid waste incineration fly ash (MSWI FA). Calcium chloride addition achieves FA stabilization/solidification by the formation and polymerization of calcium carbonate oligomers. The effects of calcium, triethylamine (TEA), and water-washing pretreatment on the solidification of heavy metals by the polymer were studied. Consequently, as more calcium was added, the solidification improved. When the ratio of TEA/Ca was increased from 2:1 to 3:1, the solidification efficiency of As and Cd increased, but it decreased when the ratio was continuously increased to 4:1. After the water-washing pre-treatment, the MSWI FA had a significantly improved solidification effect on the heavy metals, and the solidification efficiencies of zinc, copper, cadmium, chromium, lead, and arsenic were 81.9%, 90.0%, 93.5%, 91.8%, 99.6% and 95.5%, respectively. Additionally, the solidification efficiency of PCDD/Fs was 56.5%. The heavy metals and PCDD/Fs in MSWI FA solidified by physical adsorption, wrapping and chemical precipitation. The continuous calcium carbonate structure adsorbed and encased the MSWI FA, and the heavy metals in the MSWI FA were converted from a free state to carbonate precipitates through carbonation, and the carbonate precipitate was more likely to be physical solidification by calcium carbonate.
碳酸钙低聚物是凝胶态前体，可以通过低温热处理结晶形成具有整体连续结构的无机材料，该材料可以有效固化/稳定城市固体废物焚烧飞灰（MSWI FA）中的重金属。氯化钙通过碳酸钙低聚物的形成和聚合来实现 FA 的稳定/固化。研究了钙、三乙胺（TEA）和水洗预处理对聚合物固化重金属的影响。因此，随着添加的钙量增加，固化效果得到改善。当 TEA/Ca 比从 2:1 增加到 3:1 时，As 和 Cd 的固化效率增加，但当比值连续增加到 4:1 时，固化效率降低。水洗预处理后，MSWI FA 对重金属的固化效果显著提高，锌、铜、镉、铬、铅和砷的固化效率分别为 81.9%、90.0%、93.5%、91.8%、99.6%和 95.5%，PCDD/Fs 的固化效率为 56.5%。重金属和 PCDD/Fs 通过物理吸附、包裹和化学沉淀被固化在 MSWI FA 中。连续的碳酸钙结构吸附并包裹了 MSWI FA，MSWI FA 中的重金属通过碳酸化从游离态转化为碳酸盐沉淀，碳酸盐沉淀更容易通过碳酸钙进行物理固化。
