School of Materials Engineering, Changshu Institute of Technology, 215500, China; Suzhou Key Laboratory of Functional Ceramic Materials, Changshu Institute of Technology, Changshu, 215500, China.
School of Materials Engineering, Changshu Institute of Technology, 215500, China.
Environ Pollut. 2024 Dec 1;362:124984. doi: 10.1016/j.envpol.2024.124984. Epub 2024 Sep 19.
The self-cementation characteristics of arsenic (As)-contaminated soil were comprehensively investigated in this study. Different non-thermal plasma-irradiated binary (hydro)oxides of polyvalent ferromanganese (poly-Fe-Mn) were synthesized and exploratorily dispersed to soil samples to activate solidification and stabilization during the self-cemented process. The maximum compressive strength of 56.35 MPa and the lowest leaching toxicity of 0.004 mg/L were obtained in the proof test under optimal conditions (i.e., the mass ratio of the poly-Fe-Mn to the soil sample of 0.05; the mass ratio of the composite alkali activator (NaOH + CaO) to the soil sample of 0.25; the mass ratio of CaO to NaOH of 1.5; the mass ratio of the DI water to the binder of 0.515). The composite alkaline activator primarily contributed to the strength formation of the self-cemented matrix while the poly-Fe-Mn significantly influenced the reduction of the As-leaching toxicities. The poly-Fe-Mn maintained diffusion-controlled polycondensation and strengthened the nucleation process during self-cementation. The amount of water and the dosage of poly-Fe-Mn caused an interactive influence on the self-cemented solidification of contaminated soils. The solidified samples with poly-Fe-Mn exhibited better thermal decomposition than their counterparts, reflecting the enhancement of poly-Fe-Mn to the matrix. Some minerals including C-S-H, kaolinite, gehlenite, diopside sodian, augite, and albite were matched in the samples, directly demonstrating the geopolymerization-steered self-cementation of the As soil. The employment of poly-Fe-Mn not only reinforced the immobilization of As pollutants in the matrix but also induced the self-cementation of soils by intensifying the composite alkaline-activated geopolymerization kinetics.
本研究全面考察了砷（As）污染土壤的自胶结特性。合成了不同的非热等离子体辐照的多价铁锰二元（氢）氧化物，并将其探索性地分散到土壤样品中，以在自胶结过程中激活固化和稳定化。在最佳条件下（即多价铁锰与土壤样品的质量比为 0.05；复合碱激发剂（NaOH+CaO）与土壤样品的质量比为 0.25；CaO 与 NaOH 的质量比为 1.5；水与粘结剂的质量比为 0.515）的验证试验中，获得了 56.35 MPa 的最大抗压强度和 0.004 mg/L 的最低浸出毒性。复合碱激发剂主要促进自胶结基质的强度形成，而多价铁锰显著影响降低 As 的浸出毒性。多价铁锰在自胶结过程中保持扩散控制的缩聚并加强成核过程。水的量和多价铁锰的用量对污染土壤的自胶结固化有交互影响。多价铁锰固化的样品比其对应物具有更好的热分解性能，这反映了多价铁锰对基质的增强作用。在样品中匹配了包括 C-S-H、高岭石、钙沸石、透辉石钠、辉石和钠长石在内的一些矿物，直接证明了 As 土壤的地质聚合驱动的自胶结。多价铁锰的使用不仅强化了基质中 As 污染物的固定化，而且通过强化复合碱激活的地质聚合动力学，诱导了土壤的自胶结。
