The dissolution of metal sulfides, such as ZnS, plays an important role in the fate of metal contaminants in the environment. Here we examine the dissolution behavior of ZnS nanoparticles synthesized by abiogenic and biogenic methods. Biogenic ZnS were produced by reacting Zn(II) with the anaerobic, metal-reducing bacteria Thermoanaerobacter X513 in a thiosulfate-containing growth medium, whereas abiogenic ZnS was produced by mixing equimolar solutions of ZnCl2 and Na2S to make a 0.5 milimolar solution. High-resolution TEM, X-ray energy dispersive spectroscopy, and in situ liquid cell TEM were utilized to characterize the as-synthesized ZnS crystal structure, size and size distribution, defects, and aggregation behavior. Defects in the form of twinning were observed in the large (8-10 nm diameter) non-capped abiogenically produced nanostructures along the {111} sphalerite faces, while quantum dot sized (3-5 nm) nanoparticles were produced biogenically. In situ liquid cell transmission electron microscopy (LCTEM) beam induced dissolution experiments were used to assess the effect of aggregation, biologically generated capping agents, and crystal defects on the rate of dissolution. The effect of metal doping on the aggregation and dissolution behavior of biogenically produced ZnS was also investigated. These findings provide insight into abiogenic and biogenic factors that govern metal sulfide nanoparticles dissolution and bacterial production, and have implications for the fate of zinc at contaminated sites.

Formation, aggregation, and in situ dissolution behavior of abiogenically and biogenically produced ZnS nanoparticles

253rd National Meeting (2017)

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