Refinement of industrial kaolin by microbial removal of iron-bearing impurities
Refinement of industrial kaolin by microbial removal of iron-bearing impurities
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DOI：
10.1016/j.clay.2013.08.041
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发表时间：
2013-12
影响因子：
5.6
通讯作者：
A. Zegeye;S. Yahaya;C. Fialips;M. White;N. Gray;D. Manning
中科院分区：
文献类型：
--
作者：
A. Zegeye;S. Yahaya;C. Fialips;M. White;N. Gray;D. Manning
高岭土原材料的商业价值受到含铁杂质的存在和含量的极大影响，这可能对制造产品的白度和耐火度产生不利影响。由于目前用于去除这些杂质的技术的高成本和环境影响，现在一些努力的目标是开发替代方法，如生物方法。本文报道了一系列厌氧微宇宙实验，以评价希瓦氏菌属（S. algaBrY，S. oneidensisMR-1、S.腐败菌CN 32和S.腐殖酸CIP 8040），在生物浸出含铁杂质从原高岭土。所有测试的细菌菌株都能够还原和浸出高岭土中存在的三价铁，从而显著改善其颜色特性。在所检测的细菌中，S. putrefaciensCIP 8040产生了最大的改进，在30 °C下5天内ISO亮度和白度分别从74%增加到79%和从54%增加到66%。X射线衍射和红外光谱分析均未观察到高岭石的次生矿物和晶体化学蚀变。通过扫描电子显微镜观察生物处理的高岭土表明，原来的六边形形状的粘土颗粒变得不那么规则。进一步的研究和开发现在应侧重于优化生物沥滤过程的速度和程度，然后再进行更大规模的试验或工业规模应用。特别是，进一步的研究应评估环境和经济效益相比，目前使用的方法，如化学漂白与连二亚硫酸钠。
The commercial value of kaolin raw materials is greatly affected by the presence and content of iron-bearing impurities, which can have a detrimental effect on the whiteness and refractoriness of manufactured products. Because of the high cost and environmental impact of techniques currently used to remove these impurities, some effort is now targeted toward the development of alternative methods, such as biological processes. This paper reports a series of anaerobic microcosm experiments conducted to evaluate the suitability of iron-respiring bacteria (IRB) of theShewanellaspecies (S. algaBrY,S. oneidensisMR-1,S. putrefaciensCN32, andS. putrefaciensCIP 8040), in bioleaching iron-bearing impurities from raw kaolin. All tested bacterial strains were able to reduce and leach ferric iron present in the kaolin, thereby substantially improving its color properties. Among the tested bacteria,S. putrefaciensCIP8040 produced the greatest improvements, with increases in ISO brightness and whiteness from 74% to 79% and from 54% to 66%, respectively, in 5 days at 30 °C. Neither secondary mineral nor crystal-chemical alteration of the kaolinite was observed by X-ray diffraction and infrared spectroscopy. Observations of the biotreated kaolins by scanning electron microscopy showed that the original hexagonal shape of the clay particles became less regular. Further research and development should now focus on optimising the rate and extent of the bioleaching process before its application at a larger pilot or industrial scale. In particular, further studies should evaluate the environmental and economical benefits compared to currently used approaches, such as the chemical bleaching with sodium hydrosulfite.