Journal
GEOMICROBIOLOGY JOURNAL
Volume 33, Issue 10, Pages 948-953Publisher
TAYLOR & FRANCIS INC
DOI: 10.1080/01490451.2015.1137660
Keywords
Biomineralization; bioremediation; guyanaite; grimaldiite; nanosheets; organo-Cr(III)
Funding
- National Basic Research Program of China (973 Program) [2014CB846003]
- National Natural Science Foundation of China [41372346, 21477129]
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Remediation of heavy-metal contamination by biomineralization has become an environmentally very important issue in the last two decades. Here we describe the transformation of amorphous organo-Cr(III) to chromium hydroxide oxide (guyanaite/grimaldiite) by hydrothermal treatment (HTT). First, glycine-Cr(III) was synthesized to serve as a simple model for exploring the conditions favoring HTT. Cell-bound Cr(III) was obtained by the reduction of hexavalent chromium [Cr(VI)] to trivalent chromium [Cr(III)] by Bacillus cereus. Then the reduced Cr(III) was chelated by ligands at the cell surface, forming cell-bound Cr(III). Subsequently, HTT was applied to treat cell-bound Cr(III) at different temperatures and for different lengths of time. The results showed that, by this treatment at 200 degrees C for 7days or at 250 degrees C for 1day, glycine-Cr(III) was converted to trivalent chromium mineral (guyanaite/grimaldiite), having the form of nanosheets with a length of 10 approximate to 20nm and a width of 3 approximate to 5nm under the described conditions. Cell-bound Cr(III) could also be converted to guyanaite/grimaldiite at 250 degrees C for 9days if it was bound by an organic compound more complex than glycine. Our finding showed that organo-Cr(III) could be transformed into minerals by an appropriate hydrothermal process, which is applicable to bioremediation of heavy-metal pollution. Our findings also suggest that organo-Cr(III) may play an important rolein the biogeochemistry of chromium.
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