Geomicrobiology Group, School of Life Sciences, University of Dundee, Dundee, Scotland, DD1 5EH, UK.
Concrete Technology Group, Department of Civil Engineering, University of Dundee, Dundee, Scotland, DD1 4HN, UK.
Appl Microbiol Biotechnol. 2019 Jan;103(2):981-993. doi: 10.1007/s00253-018-9489-0. Epub 2018 Nov 15.
Lanthanum is an important rare earth element and has many applications in modern electronics and catalyst manufacturing. However, there exist several obstacles in the recovery and cycling of this element due to a low average grade in exploitable deposits and low recovery rates by energy-intensive extraction procedures. In this work, a novel method to transform and recover La has been proposed using the geoactive properties of Aspergillus niger. La-containing crystals were formed and collected after A. niger was grown on Czapek-Dox agar medium amended with LaCl. Energy-dispersive X-ray analysis (EDXA) showed the crystals contained C, O, and La; scanning electron microscopy revealed that the crystals were of a tabular structure with terraced surfaces. X-ray diffraction identified the mineral phase of the sample as La(CO)·10HO. Thermogravimetric analysis transformed the oxalate crystals into LaO with the kinetics of thermal decomposition corresponding well with theoretical calculations. Geochemical modelling further confirmed that the crystals were lanthanum decahydrate and identified optimal conditions for their precipitation. To quantify crystal production, biomass-free fungal culture supernatants were used to precipitate La. The results showed that the precipitated lanthanum decahydrate achieved optimal yields when the concentration of La was above 15 mM and that 100% La was removed from the system at 5 mM La. Our findings provide a new aspect in the biotransformation and biorecovery of rare earth elements from solution using biomass-free fungal culture systems.
镧是一种重要的稀土元素，在现代电子学和催化剂制造中有许多应用。然而，由于可开采矿床中的平均品位较低，以及能量密集型提取工艺的回收率较低，该元素的回收和循环存在一些障碍。在这项工作中，提出了一种使用黑曲霉的地球化学性质来转化和回收镧的新方法。在添加了 LaCl 的 Czapek-Dox 琼脂培养基上生长黑曲霉后，形成并收集了含镧的晶体。能谱分析（EDXA）表明晶体含有 C、O 和 La；扫描电子显微镜显示晶体具有阶梯状表面的板状结构。X 射线衍射确定了样品的矿物相为 La(CO)·10HO。热重分析将草酸盐晶体转化为 LaO，热分解动力学与理论计算非常吻合。地球化学模拟进一步证实，这些晶体是十水合镧，确定了其沉淀的最佳条件。为了定量晶体的产量，使用无生物质的真菌培养液来沉淀 La。结果表明，当 La 的浓度高于 15 mM 时，沉淀的十水合镧达到最佳产率，而在 5 mM La 时，系统中 100%的 La 被去除。我们的研究结果为使用无生物质真菌培养系统从溶液中生物转化和生物回收稀土元素提供了一个新的方面。
