ESNano: New Insights into the Dissimilatory Reductive Dissolution of Different Exposed Facets of Hematite
Recently, the research group of Professor Tongxu Liu from Institute of Eco-environmental and Soil Sciences, Guangdong Academy of Sciences has made new progress on the dissimilatory reductive dissolution of different exposed facets of hematite. This research was published in the journal of Environmental Science: Nano (IF = 7.683) and was selected as Outside Front Cover and Hot Article.
Microbially-mediated dissimilatory reductive dissolution of iron minerals is an important biogeochemical process in underground soils and sediments, which was considered as the important driving force of the migration and transformation of elements and pollutants. Hematite nanoparticles are widespread in the natural environment, but the exposed facets formed under different conditions were largely distinct. Previous studies of the mineral facets were mainly focused on catalysis and material chemistry. However, it is still unclear how the exposed facets of hematite affect the process of microbially-mediated dissimilatory iron reduction under anaerobic conditions.
The research team has synthesized two types of hematite with different exposed facets, including {001} crystal plane of hexagonal nanoplates and {100} crystal plane of nanorods. It was found that the reducing activity of the hematite {001} was higher than that of hematite {100}. Furthermore, the reducing activity of different exposed facets of hematite was also affected by the surface electrochemical properties and the amount of cell adhesion. First, the hematite {001} has high conductivity and low resistance, which make it easier to accept extracellular electrons from Shewanella, and thereby produce more ferrous iron. Secondly, the hematite {001} has high surface hydroxyl functional groups, zero point of charge, and redox potential, which was easily combined with the negatively charged Shewanella, and was easily reduced. Therefore, the different exposed facets of natural minerals can affect cell adhesion and biofilms formation, and further affect mineral dissolution, and potentially the pollutant migration and transformation.
This research deepens the understanding of the mineral-microbe interaction mechanism from the perspective of mineral crystal and surface structures.
Paper link: https://pubs.rsc.org/en/content/articlelanding/2020/en/d0en00555j#!divAbstract.