Manganese and cobalt redox cycling in laterites; Biogeochemical and bioprocessing implications
Manganese and cobalt redox cycling in laterites; Biogeochemical and bioprocessing implications
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DOI：
10.1016/j.chemgeo.2019.119330
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发表时间：
2020-01
期刊：
影响因子：
3.9
通讯作者：
L. Newsome;Agustín Solano Arguedas;V. Coker;C. Boothman;J. Lloyd
中科院分区：
文献类型：
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作者：
L. Newsome;Agustín Solano Arguedas;V. Coker;C. Boothman;J. Lloyd
钴对于支撑我们经济脱碳的现代技术至关重要，但其供应有限，导致其被指定为关键金属。人们对钴的地球化学性质知之甚少，但了解地球化学循环如何影响钴的行为，有助于开发从矿石中回收钴的新技术，从而提高供应的安全性。红土是钴的重要来源，它们主要使用能源或化学密集型工艺加工镍，钴作为副产品回收。金属还原条件刺激红土沉积物的微观世界中，通过添加简单和廉价的有机底物（醋酸盐或葡萄糖）。在实验结束时，容易回收的钴（水溶性或用乙酸提取的）的量从< 1%增加到高达64%，这密切反映了锰的行为，而只有一小部分铁转化为容易回收的相。微生物群落的测序表明，有机底物的加入刺激了与已知的锰（IV）/铁（III）还原剂密切相关的土著原核生物的生长，特别是从梭菌目，并确定了被分配给青霉菌属的真菌，该真菌已知产生有利于从红土中浸出钴和镍的有机酸。总体而言，结果表明，红土中钴的环境行为可能是由微生物锰的地球化学循环控制。这些结果是令人信服的，因为在来自不同大陆的四种红土（Acoje，AlaldaExpense，Piauí和Shevchenko）中观察到了类似的行为。提出了一种新的生物处理策略，即红土用有机基质处理以产生金属还原条件，然后用乙酸冲洗以除去钴。有机基质不仅是环境友好的，而且可能来自废弃的碳基质，最少量的氧化铁被调动，因此产生的废物更少。
Cobalt is essential for the modern technology that underpins the decarbonisation of our economies, but its supply is limited leading to its designation as a critical metal. Cobalt biogeochemistry is poorly understood, yet knowledge of how biogeochemical cycling impacts cobalt behaviour could assist the development of new techniques to recover cobalt from ores, and so improve the security of supply. Laterites are an important source of cobalt, they are primarily processed for nickel using energy or chemical intensive processes, with cobalt recovered as a by-product. Metal-reducing conditions were stimulated in laterite sediment microcosms by the addition of simple and cheaply available organic substrates (acetate or glucose). At the end of the experiment the amount of easily recoverable cobalt (aqueous or extractable with acetic acid) increased from < 1% to up to 64%, which closely mirrored the behaviour of manganese, while only a small proportion of iron was transformed into an easily recoverable phase. Sequencing of the microbial community showed that the addition of organic substrates stimulated the growth of indigenous prokaryotes closely related to known manganese(IV)/iron(III)-reducers, particularly from the Clostridiales, and that fungi assigned toPenicillium,known to produce organic acids beneficial for leaching cobalt and nickel from laterites, were identified. Overall, the results indicate that the environmental behaviour of cobalt in laterites is likely to be controlled by manganese biogeochemical cycling by microorganisms. These results are compelling given that similar behaviour was observed in four laterites (Acoje, Çaldağ, Piauí and Shevchenko) from different continents. A new bioprocessing strategy is proposed whereby laterites are treated with an organic substrate to generate metal-reducing conditions, then rinsed with acetic acid to remove the cobalt. Not only are organic substrates environmentally-friendly and potentially sourced from waste carbon substrates, a minimal amount of iron oxides was mobilised and consequently less waste generated.