氧化亚铁硫杆菌浸铜研究及胞外多聚物的作用

为了获得氧化亚铁硫杆菌(Acidithiobacillus ferrooxidans,A.f)以及胞外多聚物(extracellular polymeric sub-stances,EPS)对铜浸出的作用结果,进行了透析袋实验,设置2个处理,2者的浸出液均为成熟菌液,但一个将铜片装入透析袋中以隔离A.f及EPS与铜的直接接触。结果表明:(1)菌液的处理和加透析袋的处理中铜都得到了浸出,240 h铜的浸出浓度分别为6 796 mg/L和1 366 mg/L,可知A.f及EPS与铜片直接接触能促进铜的浸出;(2)透析袋的处理中Fe3+保持较高浓度,说明Fe3+与EPS络合后被阻挡在透析袋外面从而不能与铜反应,可知EPS在A.f浸铜中起了媒介载体的作用;(3)2者的SEM图表明无透析袋的处理A.f与铜在实验初期发生了吸附,实验后期则无,实验初期铜快速浸出是由于传质距离短,而后期速度变缓是由于传质距离增大。

Bioleaching of copper with Acidithiobacillus ferrooxidans and role of its extracellular polymeric substances

In order to obtain the roles of Acidithiobacillus ferrooxidans (ab. A.f.) and extracellular polymeric substances (EPS) in the bioleaching of copper, the experiment with two controls which were both imerged in the same solution with A.f. but one of them with the copper putting into the dialysis bag to stop the direct contact between A.f. and copper was carried out. The experimental results show that: (1) copper has been leached in both of the two processings, and the concentration of copper leached in the solution without and with the dialysis bag are 6 796 mg/L and 1 366 mg/L respectively after leaching for 240 h, so the direct contact between A.f. and copper promoting the bioleaching of copper can be inferred; (2) EPS is important in the bioleaching of copper with A.f. The EPS combined with Fe³⁺ and mediated the reaction between Fe³⁺ and copper; (3) the SEM graphs of copper in the two processing show that A.f. adsorption to copper only occurred in the initial stages of the experiment, the rapid leaching of copper in the initial experiment may due to the short mass transfer distance, while the leaching of copper slowing down may due to the increasing mass transfer distance.