溴代阻燃剂对氧化亚铁硫杆菌浸提废旧电脑主板覆层铜的影响

以破碎至10~20目(0.84~2.00 mm)的废旧电脑主板颗粒为试验材料,分为未处理(未去除溴代阻燃剂的主板颗粒)、处理(去除30%溴代阻燃剂的主板颗粒)、加萃取物(处理主板颗粒和萃取物)、对照4组. 以CCl₄作为萃取剂,采用固液萃取技术,分析了在微生物作用下不同处理组中ρ(Cu²⁺)、ρ(Fe³⁺)、Eh(氧化还原电位)和pH的变化,以考察溴代阻燃剂对氧化亚铁硫杆菌(Thiobacillus ferrooxidans)浸Cu率的影响. 结果表明:随着浸提时间的增加,氧化亚铁硫杆菌对未处理、处理和加萃取物3组的浸Cu率不同,其中处理组最好,加萃取物组最差. 浸提过程中,ρ(Fe³⁺)、Eh和pH与微生物活性、浸Cu率显著相关,表现为微生物活性越好,ρ(Cu²⁺)和pH越大,ρ(Fe³⁺)和Eh越小. 浸提24和168 h,处理组的浸Cu率比未处理组分别提高了14.11%和17.37%； 而加萃取物组的浸Cu率比未处理组分别降低了27.69%和21.67%. 表明废旧电脑主板中的溴代阻燃剂是影响微生物浸Cu率的重要因素之一. 为进一步提高浸Cu率,必须考虑溴代阻燃剂对微生物生长的影响.

Study on the Influence of Brominated Flame Retardants on the Bio-Leaching of Copper from Waste Computer Motherboards

The influence of brominated flame retardants on the bio-leaching of copper from waste computer motherboards by Thiobacillus ferrooxidans was studied. After the powder with mesh size 0.84-2.00 mm was collected, different kinds of samples were added into the solution to obtain four series with the raw waste computer motherboards:untreated waste computer motherboards, treated waste computer motherboards, treated waste computer motherboards and extractant, and the control group (without waste computer motherboards). Solid-liquid extraction with CCl₄ as the extractant was employed to remove the brominated substances on the waste computer motherboards. After each time interval, Fe ions and Cu ions were sampled and determined. ORP(E_h) and pH were also recorded. The results showed that the leaching efficiency of copper from the raw waste computer motherboards, the treated ones and the extractant groups were different during leaching. The treatment group had the best performance, while the extractant one had the worst. The content of Fe ions and the values of E_h and pH showed a relationship with microbial activity and the content of Cu ions during the leaching process. The larger the microbial activity was, the greater the content of Cu ions and the value of pH were, while the trend of the other two indexes were opposite. Otherwise, the content of Cu ions and values of pH were small, while the content of Fe ions and the value of E_h were large. After leaching for 24 hours, as compared with the untreated group, the Cu leaching efficiency of the treated group was 14.11% higher, while the efficiency of the extractant treated group was lower by 27.69%. After leaching for 168 hours, as compared with the untreated group, the Cu leaching efficiency of the treated group was 17.37% higher, while the efficiency of the extractant treated group was lower by 21.67%. The experimental results showed that the use of brominated flame retardants on waste computer motherboards was one of the important factors affecting copper leaching efficiency. In order to further improve the copper leaching efficiency, we must consider the effect of the brominated flame retardants on the growth of microorganisms.