废旧印刷线路板中溴代阻燃剂对微生物浸提金属铜效率的影响

研究废旧印刷线路板中溴代阻燃剂的多寡对氧化亚铁硫杆菌(Thiobacillus ferrooxidans)浸提废旧印刷线路板金属铜的浸出效率的影响。将废旧印刷线路板剪切破碎后过筛,得到不同粒度段的颗粒样品,分别测定不同颗粒样品中溴代阻燃剂的含量,以含溴量最高的40~100目的颗粒作为试验材料,探讨不同样品浓度(5g/L、15g/L和25g/L),萃取部分溴代阻燃剂与未萃取两种条件下T.ferrooxidans浸提金属铜的效率。在500mL三角瓶中接入活化后的T.ferrooxidans,待菌株培养到对数生长期后加入相应样品,摇床培养120h,每隔一定时间取上清液,分别测定上清液中Cu2+、氧化还原电位(ORP)和pH值。结果为,浸提120h后,未萃取溴代阻燃剂的5g/L、15g/L和25g/L浓度时T.ferrooxidans对铜浸出分别是79.59%、90.53%和66.37%;萃取溴代阻燃剂的5g/L、15g/L和25g/L浓度时T.ferrooxidans对铜的浸出浓度分别是90.98%、97.88%和69.05%。表明溴代阻燃剂是影响微生物浸铜效率的重要因素之一,利用CCl4作为萃取剂萃取废旧印刷线路板中溴代阻燃剂后,T.ferrooxidans对废旧印刷线路板金属铜的浸提率提高,废旧印刷线路板加入量为15g/L时浸提金属铜的效率最高。

Effects of Brominated Flame Retardants on the Bacterial Leaching of Copper from Waste Printed Circuit Boards

The aim of this study is to investigate the process of bacterial leaching of copper from waste printed circuit boards (WPCBs), and to evaluate the influence of brominated flame retardants (BFRs) on the leaching ratio of copper. The waste printed circuit boards can be used after crushed and sieved to get different-size particles, and then determine the contents of brominated flame retardants in the particle samples. 40- to 100-mesh particles contain the highest amount of bromine as experimental materials. Explore the Thiobacillus ferrooxidans leaching efficiency of copper on the samples of different concentrations (5 g/L, 15 g/L and 25 g/L) of waste printed circuit boards under the conditions of extracting and not extracting brominated flame retardants. In a 500 mL flask, the activated bacteria were inoculated and cultured until logarithmic growth phase, and then an appropriate amount of sample was added, followed by 120 h culture shaking. The supernatant was sampled, at regular intervals. The concentration of Cu²⁺, ORP value and pH value were measured. After 120 hours of bioleaching, the leaching ratios of copper would be 79.59%, 90.53% and 66.37% for the no extraction of WPCBs concentrations of 5 g/L, 15 g/L and 25 g/L, respectively, the leaching ratios were 90.98%, 97.88% and 69.05% for the extraction of WPCBs. BFRs showed that was one of the important factors affecting the efficiency of microbial leaching of copper. After CCl₄ was used as the extraction solvent to extract waste BFRs in printed circuit boards, the extraction rate of T. ferrooxidans for copper from printed circuit boards increased to a certain extent. When the added optimal amount of W PCBs was 15 g/L, the leaching efficiency of copper would be best.