Finzgar Neza, Lestan Domen
Agronomy Department, Biotechnical Faculty, University of Ljubljana, Slovenia.
Chemosphere. 2006 Jun;63(10):1736-43. doi: 10.1016/j.chemosphere.2005.09.015. Epub 2005 Nov 8.
The feasibility of a novel EDTA-based soil heap leaching method with treatment and reuse of extractants in a closed process loop was evaluated on a laboratory scale. Ozone and UV irradiation were used for oxidative decomposition of EDTA-metal complexes in extractants from Pb (1243 mg kg(-1)) and Zn (1190 mg kg(-1)) contaminated soil. Released metals were absorbed in a commercial metal absorbent Slovakite. Six-consecutive additions of 2.5 mmol kg(-1) EDTA (total 15 mmol kg(-1) EDTA) removed 49.6 +/- 0.6% and 19.7 +/- 1.7% of initial total Pb and Zn from soil (4.6 kg) packed in 22 cm high columns. The efficiency of extraction was similar to small-scale simulations of heap leaching (15 0 g of soil), where EDTA used in the same manner removed 49.7 +/- 1.0% and 13.7 +/- 0.4% of Pb and Zn. The new heap leaching method produced discharge extractant with fairly low final concentrations of Pb, Zn and EDTA (1.98 +/- 2.17 mg l(-1), 4.55 +/- 2.36 mg l(-1), and 0.05 +/- 0.04 mM, respectively), which could presumably be reduced even further with continuation of treatment. The results of our study indicate that for soils contaminated primarily with Pb, treating the EDTA extractants with ozone/UV and reuse of extractants enables efficient soil heap leaching with very little or no wastewater generation, easy control over emissions, and lowers the requirements for process water.
在实验室规模上评估了一种基于乙二胺四乙酸（EDTA）的新型土壤堆浸出方法在封闭工艺回路中处理和再利用萃取剂的可行性。臭氧和紫外线辐射用于氧化分解来自铅（1243毫克/千克）和锌（1190毫克/千克）污染土壤的萃取剂中的EDTA-金属络合物。释放出的金属被一种商业金属吸附剂斯洛伐克石吸收。连续六次添加2.5毫摩尔/千克的EDTA（总计15毫摩尔/千克的EDTA）从装在22厘米高柱中的4.6千克土壤中去除了49.6±0.6%的初始总铅和19.7±1.7%的初始总锌。萃取效率与小规模堆浸模拟（150克土壤）相似，以相同方式使用的EDTA去除了49.7±1.0%的铅和13.7±0.4%的锌。这种新的堆浸出方法产生的排放萃取剂中铅、锌和EDTA的最终浓度相当低（分别为1.98±2.17毫克/升、4.55±2.36毫克/升和0.05±0.04毫摩尔/升），随着处理的继续，这些浓度可能会进一步降低。我们的研究结果表明，对于主要受铅污染的土壤，用臭氧/紫外线处理EDTA萃取剂并再利用萃取剂能够实现高效的土壤堆浸出，产生极少或不产生废水，易于控制排放，并降低对工艺用水的要求。
