2024-03-28T11:10:46Zhttp://digital.csic.es/dspace-oai/requestoai:digital.csic.es:10261/1881992019-11-12T13:22:51Zcom_10261_39226com_10261_8col_10261_39228
Jiménez, Amalia
Astilleros, José Manuel
Fernández Díaz, Lurdes
Fernández González, Ángeles
Pérez-Garrido, Carlos
Cubillas, P.
Prieto, Manuel
2019-08-14T06:46:41Z
2019-08-14T06:46:41Z
2016-09-11
2nd European Mineralogical Conference (2016)
http://hdl.handle.net/10261/188199
Copper is present in igneous and sedimentary rocks in minor to trace amounts. Copper
participates in numerous essential to life biological processes and is considered a strategic
element for a variety of industrial and agricultural applications. Copper can be released to
the environments as a component of wastewaters, which can increase its concentration in
natural waters to reach values considered toxic for the health of organisms. Previous works
have demonstrated that the surfaces of abundant calcium bearing rock-forming minerals
like calcite, aragonite and gypsum are efficient uptakers of dissolved metals.
Understanding the mechanism involved in the interaction between these minerals and
waters bearing metals should help to develop improved strategies for the treatment of
mining wastes. In this work, we focus on waters bearing copper and study their interaction
with calcite, aragonite and gypsum combining microscopic and nanoscopic observations.
We aim to obtain information on their relative effectiveness as copper uptakers, for which
we have conducted series of batch type and AFM experiments at room temperature. The
batch type sorption experiments involved the reaction of ~1 g of 1.0-1.5 mm sized
fragments of the corresponding calcium bearing mineral with CuNO3 (1.0, 5.0 and 10mM)
in thermostat closed polypropylene vessels during increasing reaction times (between 1 and
12 days). Chemical analyses of the aqueous solution after different elapsed times evidence
that the interaction with any of the three calcium-bearing minerals results in the removal of
dissolved copper. The characterization of the interacted mineral fragments by scanning
electron microscopy (SEM) and conventional powder glancing X-ray diffraction (XRD)
shows the development of rough surfaces on the minerals accompanied by the formation of
randomly distributed malachite (Cu2CO3(OH)2) spherulites. The reaction mechanisms
involve the continuous dissolution of the primary phase followed by the precipitation of
malachite regardless the calcium-bearing primary phase. The rate of dissolution directly
relates to the initial concentration of copper in the aqueous solution in all three cases.
However, the degree of surface coverage by malachite precipitates significantly differs
depending on the substrate. Thus, while precipitates cover wide areas of aragonite surfaces,
they form isolated patches on specific areas of the surfaces of calcite and gypsum. AFM
observations confirm the strong interaction between all solid and copper-bearing aqueous
solutions, with etch pits rapidly forming and coalescing and a new, epitactic-related phase
immediately forming on the substrate. Our results once again evidence the relevance of
mineral-water interactions in controlling the fate of pollutants and the suitability of
mineral/water interaction-based strategies to control and remedy mining-related
contamination.
eng
closedAccess
Interaction of cu-bearing solutions with calcite, aragonite and gypsum: a comparative study
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