The physicochemical profiling of e-waste was done by AAS, XRD, and SEM with EDX that reveals the composition of valuable metals like Au−, Ag−, Zn−, and Cu−. Thus, the present findings provide the important resource of precious metal in the e-waste (PCBs) as pollutant in the environment and human impact. The native isolates Frankia sp. DDNSF-01 and Frankia casuarinae DDNSF-02 were subjected for bioleaching of gold and precious elements bearing e-waste under one and two-step leaching methods. The two-step bioleaching protocol was found effectual in expression with high level of metal leaching within the culture medium of Frankia metabolites and organic acids which were obtained by the leaching of metals. The presence of organic acids functional groups was determined by FT-IR spectrum and by low pH of growth medium. The AAS analysis quantified the initial concentration of metals and their significant increase brought by the leaching. The initial concentration of precious metal elements was found in the e-waste like Au−, Ag−, Cu−, and Zn− (0.04, 0.05, 0.35, 0.1 mg/g) respectively. Frankia sp. leached out precious metals like Au−, Ag−, Cu−, and Zn− (0.2, 0.14, 0.68, 0.2 mg/g) respectively. Frankia casuarinae leached out precious metals like Au−, Ag−, Cu−, and Zn− (0.25, 0.15, 0.55, and 0.2 mg/g) respectively. The precious metal gold was highly leached out by F. casuarinae than Frankia sp.. The valuable metal copper was significantly increased by Frankia sp. than F. casuarinae. Higher gold recovery, at 75%, was obtained for F. casuarinae and copper 94% recovery by Frankia sp. bioleaching of the biooxidised e-waste at 0.2% low pulp densities. The results were confirmed by XRD and SEM with EDX analysis.

中文翻译：

---

生物浸出 Frankia 从受环境污染的电子垃圾印刷电路板中回收黄金和其他贵金属资源

电子废物的物理化学分析是通过 AAS、XRD 和 SEM 与 EDX 完成的，它揭示了有价金属（如 Au-、Ag-、Zn- 和 Cu-）的组成。因此，目前的研究结果提供了电子废物（PCBs）中贵金属的重要资源，作为环境中的污染物和人类影响。本地分离出 Frankia sp。DDNSF-01 和 Frankia casuarinae DDNSF-02 在一步和两步浸出方法下对含有电子废物的黄金和贵重元素进行生物浸出。发现两步生物浸出方案在弗兰基亚代谢物和通过金属浸出获得的有机酸的培养基中以高水平金属浸出的表达是有效的。有机酸官能团的存在由 FT-IR 光谱和生长培养基的低 pH 值确定。AAS 分析量化了金属的初始浓度和浸出带来的显着增加。在电子废物中发现贵金属元素的初始浓度分别为 Au-、Ag-、Cu- 和 Zn-（0.04、0.05、0.35、0.1 毫克/克）。弗兰克亚 sp. 分别浸出 Au−、Ag−、Cu− 和 Zn− 等贵金属（0.2、0.14、0.68、0.2 毫克/克）。Frankia casuarinae 分别浸出贵金属，如 Au-、Ag-、Cu- 和 Zn-（0.25、0.15、0.55 和 0.2 mg/g）。F. casuarinae 对贵金属金的浸出率高于 Frankia sp.。Frankia sp. 显着增加了贵金属铜。比 F. casuarinae。F. casuarinae 获得了更高的金回收率，为 75%，Frankia sp. 获得了 94% 的铜回收率。以 0.2% 的低纸浆密度对生物氧化电子废物进行生物浸出。