Pedersen Anne Juul, Ottosen Lisbeth M, Villumsen Arne
Department of Civil Engineering, Technical University of Denmark, Kemitorvet, Building 204, DK-2800 Kgs., Lyngby, Denmark.
J Hazard Mater. 2003 Jun 27;100(1-3):65-78. doi: 10.1016/s0304-3894(03)00064-5.
Electrodialytic remediation, an electrochemically assisted extraction method, has recently been suggested as a potential method for removal of heavy metals from fly ashes. In this work, electrodialytic remediation of three different fly ashes, i.e. two municipal solid waste incinerator (MSWI) fly ashes and one wood combustion fly ash was studied in lab scale, and the results were discussed in relation to the expected heavy metal speciation in the ashes. The pH-dependent desorption characteristics for Cr differed between the two MSWI ashes but were similar for Cd, Pb, Zn and Cu. Thus, it was expected that the speciation of Cd, Pb, Zn and Cu was similar in the two ashes. However, in succeeding electrodialytic remediation experiments significant differences in removal efficiencies were observed, especially for Pb and Zn. In analogous electrodialytic remediation experiments, 8% Pb and 73% Zn was removed from one of the MSWI ashes, but only 2.5% Pb and 24% Zn from the other. These differences are probably due to variations in pH and heavy metal speciation between the different ashes. Cd, the sole heavy metal of environmental concern in the wood ash, was found more tightly bonded in this ash than in the two MSWI ashes. Approximately 70% Cd was removed from both types of ashes during 3 weeks of electrodialytic remediation, although the total concentration was a factor of 10 lower in the wood ash. It was suggested that complex Cd-silicates are likely phases in the wood ash whereas more soluble, condensed phases are dominating in the MSWI ashes.
电渗析修复作为一种电化学辅助提取方法，最近被认为是从飞灰中去除重金属的一种潜在方法。在本研究中，对三种不同的飞灰进行了实验室规模的电渗析修复研究，即两种城市固体废物焚烧炉（MSWI）飞灰和一种木材燃烧飞灰，并结合飞灰中预期的重金属形态对结果进行了讨论。两种MSWI飞灰中Cr的pH依赖解吸特性不同，但Cd、Pb、Zn和Cu的相似。因此，预计两种飞灰中Cd、Pb、Zn和Cu的形态相似。然而，在后续的电渗析修复实验中，观察到去除效率存在显著差异，尤其是Pb和Zn。在类似的电渗析修复实验中，从一种MSWI飞灰中去除了8%的Pb和73%的Zn，但从另一种飞灰中仅去除了2.5%的Pb和24%的Zn。这些差异可能是由于不同飞灰之间pH值和重金属形态的变化所致。木材飞灰中唯一受环境关注的重金属Cd，在这种飞灰中的结合比在两种MSWI飞灰中更紧密。在3周的电渗析修复过程中，两种飞灰中约70%的Cd被去除，尽管木材飞灰中的总浓度低了10倍。有人认为，Cd-硅酸盐络合物可能是木材飞灰中的主要相，而更易溶的凝聚相在MSWI飞灰中占主导地位。
