Choi Moon-Sung, Cho Kyung-Suk, Kim Dong-Su, Kim Dong-Jin
Environmental Science and Engineering, Ewha Womans University, Seoul, Korea.
J Environ Sci Health A Tox Hazard Subst Environ Eng. 2004;39(11-12):2973-82.
The bioleaching of copper contained in the printed circuit boards (PCB) of waste computers by A. ferrooxidans was studied. The Fe oxidation rates by A. ferrooxidans in the 9K medium supplemented with the leachate of PCB (0.15-0.13 g L(-1) d(-1)) were similar to that in the 9K medium without the leachate (0.15 g L(-1) d(-1)). This finding suggests that the leachate of PCB did not seriously affect the bioleaching process by this bacterium. The amount of copper leached from PCB shreds increased with the addition of ferrous ion and reached up to 5190 mg L(-1) when the initial concentration of Fe2+ ion was 7 g L(-1). As the microbial leaching progressed, pale brown precipitate was observed to form in the solution. Based on the total amount of copper, both in solution and precipitate, the optimal addition of ferrous ion for the leaching of copper was around 7 g L(-1). When citric acid was not added, only about 37 wt% of the total leached copper remained dissolved; however, the amount of dissolved copper increased to greater than 80 wt% in the presence of citric acid. This fact indicates that the addition of a complexing agent (citric acid) to the bioleaching solution can raise the solubility of the leached metal ions.
研究了氧化亚铁硫杆菌对废旧计算机印刷电路板（PCB）中含铜物质的生物浸出。在添加了PCB浸出液（0.15 - 0.13 g L(-1) d(-1)）的9K培养基中，氧化亚铁硫杆菌的铁氧化速率与未添加浸出液的9K培养基中的铁氧化速率（0.15 g L(-1) d(-1)）相似。这一发现表明，PCB浸出液不会严重影响该细菌的生物浸出过程。从PCB碎片中浸出的铜量随着亚铁离子的添加而增加，当初始Fe2+离子浓度为7 g L(-1)时，浸出量达到5190 mg L(-1)。随着微生物浸出的进行，观察到溶液中形成浅棕色沉淀。基于溶液和沉淀中的总铜量，浸出铜的亚铁离子最佳添加量约为7 g L(-1)。当不添加柠檬酸时，浸出的总铜中只有约37 wt%保持溶解状态；然而，在柠檬酸存在的情况下，溶解铜的量增加到大于80 wt%。这一事实表明，向生物浸出溶液中添加络合剂（柠檬酸）可以提高浸出金属离子的溶解度。
