VTT Technical Research Centre, P.O. Box 1000, FI-02044 VTT, Finland.
J Hazard Mater. 2010 Oct 15;182(1-3):869-76. doi: 10.1016/j.jhazmat.2010.06.128. Epub 2010 Jul 7.
Removal of Cu, Cr and As from utility poles treated with chromated copper arsenate (CCA) was investigated using different one- to three-step combinations of oxalic acid extraction and electrokinetic treatment. The experiments were carried out at room temperature, using 0.8% oxalic acid and 30 V (200 V/m) of direct current (DC) or alternating current in combination (DC/AC). Six-hour extraction removed only 15%, 11% and 28% and 7-day electrokinetic treatment 57%, 0% and 17% of Cu, Cr and As from wood chips, respectively. The best combination for all the metals was a three-step process consisting of pre-extraction, electrokinetics and post-extraction steps, yielding removals of 67% for Cu, 64% for Cr and 81% for As. Oxalic acid extraction prior to electrokinetic treatment was deleterious to further removal of Cu, but it was necessary for Cr and As removal. Chemical equilibrium modelling was used to explain the differences in the behaviour of Cu, Cr and As. Due to the dissimilar nature of these metals, it appeared that even more process sequences and/or stricter control of the process conditions would be needed to obtain the >99% removals required for safe recycling of the purified wood material.
采用草酸单步及一至三步组合提取与电动处理法，研究了从经铬酸铜砷酸（CCA）处理的电线杆中去除 Cu、Cr 和 As 的情况。实验在室温下进行，采用 0.8%草酸和 30V（200V/m）直流电或交流电联合（DC/AC）。6 小时的提取仅去除了木屑中 15%、11%和 28%的 Cu、Cr 和 As，7 天的电动处理分别去除了 57%、0%和 17%的 Cu、Cr 和 As。对于所有金属而言，最佳组合是由预提取、电动处理和后提取三步组成的过程，Cu 的去除率为 67%，Cr 的去除率为 64%，As 的去除率为 81%。电动处理前的草酸提取对进一步去除 Cu 是有害的，但对于 Cr 和 As 的去除则是必要的。化学平衡模型被用于解释 Cu、Cr 和 As 行为的差异。由于这些金属性质不同，似乎需要更多的处理序列和/或更严格地控制处理条件，才能实现安全回收净化木材所需的>99%的去除率。
