Yin Lu, Yang Hong-Ying, Tong Lin-Lin, Ma Peng-Cheng, Zhang Qin, Zhao Miao-Miao
Key Laboratory for Ecological Metallurgy of Multimetallic Mineral (Ministry of Education), Northeastern University, Shenyang, China.
School of Metallurgy, Northeastern University, Shenyang, China.
Front Microbiol. 2020 Aug 4;11:1773. doi: 10.3389/fmicb.2020.01773. eCollection 2020.
In arsenopyrite bioleaching, the interfacial reaction between mineral and cells is one of the most important factors. The energy of the interface is influenced by the mineralogical and microbiological characteristics. In this paper, the interfacial energy was calculated, and the surface of arsenopyrite during the bioleaching process was characterized by 3D laser microscopy, scanning electron microscopy with energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy, in order to assess the dissolution and oxidation behavior of arsenopyrite during bioleaching. The results showed that the contact angles of arsenopyrite were 22 ± 2° when covered with biofilms, but the reaction surface of arsenopyrite turned 103 ± 2°. However, the angle was 45-50° when covered by passive layer, which was half as that of arsenopyrite surface. The interfacial energy of arsenopyrite without biofilms increased from 45 to 62 mJ/m, while it decreased to 5 ± 1 mJ/m when covered by biofilms during the leaching process. The surface was separated into fresh surface, oxidized surface, and (corrosion) pits. The interfacial energy was influenced by the fresh and oxidized surfaces. Surface roughness increased from 0.03 ± 0.01 to 5.89 ± 1.97 μm, and dissolution volume increased from 6.31 ± 0.47 × 10 to 2.72 ± 0.49 × 10 μm. The dissolution kinetics of arsenopyrite followed the model of K = lnX, and the dissolution mechanisms were mixed controlled: surface reaction control and diffusion through sulfur layer. On the surface of arsenopyrite crystal, the oxidation steps of each element can be described as: for Fe, Fe(II)-(AsS)→Fe(III)-(AsS)→Fe(III)-OH or Fe(III)-SO; for S, As-S(-1) or Fe-S(-1)→polysulfide S→intermediate S-O→sulfate; and for As, As-S→As→As-O→As-O→As-O.
在毒砂生物浸出过程中，矿物与细胞之间的界面反应是最重要的因素之一。界面能受矿物学和微生物学特性的影响。本文计算了界面能，并通过三维激光显微镜、能量色散X射线光谱扫描电子显微镜和X射线光电子能谱对生物浸出过程中毒砂的表面进行了表征，以评估毒砂在生物浸出过程中的溶解和氧化行为。结果表明，毒砂表面覆盖生物膜时接触角为22±2°，但毒砂的反应表面变为103±2°。然而，当被钝化层覆盖时，该角度为45 - 50°，是毒砂表面角度的一半。未覆盖生物膜的毒砂界面能从45增加到62 mJ/m，而在浸出过程中被生物膜覆盖时，界面能降至5±1 mJ/m。表面分为新鲜表面、氧化表面和（腐蚀）坑。界面能受新鲜表面和氧化表面的影响。表面粗糙度从0.03±0.01增加到5.89±1.97μm，溶解体积从6.31±0.47×10增加到2.72±0.49×10μm。毒砂的溶解动力学遵循K = lnX模型，溶解机制为混合控制：表面反应控制和通过硫层的扩散。在毒砂晶体表面，各元素的氧化步骤可描述为：对于Fe，Fe(II)-(AsS)→Fe(III)-(AsS)→Fe(III)-OH或Fe(III)-SO；对于S，As-S(-1)或Fe-S(-1)→多硫化物S→中间产物S-O→硫酸盐；对于As，As-S→As→As-O→As-O→As-O。
