Wang Lei, Zhang Yuying, Chen Liang, Guo Binglin, Tan Yongshan, Sasaki Keiko, Tsang Daniel C W
Institute of Construction Materials, Technische Universität Dresden, 01062 Dresden, Germany.
Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China.
J Hazard Mater. 2022 Feb 5;423(Pt A):127025. doi: 10.1016/j.jhazmat.2021.127025. Epub 2021 Aug 25.
Municipal solid waste incineration (MSWI) fly ash is a typical hazardous waste worldwide. In this study, an innovative magnesium oxysulfate cement (MOSC) binder was designed for stabilization/solidification (S/S) of MSWI fly ash, focusing on the interactions between MOSC binder and typical metallic cations (Pb)/oxyanions (AsO). Experimental results showed that Pb and As slightly inhibited the reaction of high-sulfate 5MS system but significantly suppressed the reaction process of low-sulfate 10MS system. The 5MS binder system exhibited excellent immobilization efficiencies (99.8%) for both Pb and As. The extended X-ray absorption fine structure spectra suggested that Pb coordinated with SO/OH in the MOSC system and substituted Mg ion sites in the internal structure of 5Mg(OH)·MgSO.7HO (5-1-7) phase. In contrast, the AsO substituted SO sites with the formation of inner-sphere complexes with Mg in the large interlayer space of the 5-1-7 structure. Subsequent MSWI fly ash S/S experiments showed that a small amount of reactive Si in MSWI fly ash interfered with the MOSC reaction and adversely influenced the immobilization efficiencies of Pb, As, and other elements. Through the use of 33 wt% tailored MOSC binder for MSWI fly ash treatment, a satisfying S/S performance could be achieved.
城市固体垃圾焚烧（MSWI）飞灰是全球典型的危险废物。本研究设计了一种创新的硫酸镁水泥（MOSC）粘结剂用于MSWI飞灰的稳定化/固化（S/S），重点关注MOSC粘结剂与典型金属阳离子（Pb）/阴离子（AsO）之间的相互作用。实验结果表明，Pb和As对高硫酸盐5MS体系的反应有轻微抑制作用，但显著抑制了低硫酸盐10MS体系的反应过程。5MS粘结剂体系对Pb和As均表现出优异的固定效率（99.8%）。扩展X射线吸收精细结构光谱表明，Pb在MOSC体系中与SO/OH配位，并取代了5Mg(OH)·MgSO.7HO（5-1-7）相内部结构中的Mg离子位点。相比之下，AsO在5-1-7结构的大层间空间中取代SO位点并与Mg形成内球络合物。随后的MSWI飞灰S/S实验表明，MSWI飞灰中少量的活性Si干扰了MOSC反应，并对Pb、As和其他元素的固定效率产生不利影响。通过使用33 wt%定制的MOSC粘结剂处理MSWI飞灰，可以实现令人满意的S/S性能。
