Highly-defective nanocrystals of ZnS formed via dissimilatory bacterial sulfate reduction: A comparative study with their abiogenic analogues

Abstract

The physicochemical properties of a (nano)mineral are strongly affected by its formation processes, and thus, may indicate the (nano)mineral's formation environment and mechanism. This correlation, although relevant to a myriad of geological, environmental, and materialscience processes, has not yet been fully appreciated and systematically explored. Here, using the Zn-S system, we demonstrate that biological and abiotic processes at similar experimental conditions can produce distinctive particle size, morphology, and crystal structure in the formed ZnS. Specifically, bacterial sulfate reduction led to the formation of highly-defective nanocrystals of mixed sphalerite and wurtzite in a range of ~ 4-12 nm. By comparison, the abiotic procedures of titration-or diffusion-controlled precipitation resulted in the formation of polycrystalline aggregates that contained randomly-oriented, ultrafine crystals below ~2-3 nm. The poor crystallinity in the abiogenic samples, regardless of the sulfide addition rates, reveals

Complete removal of arsenic and zinc from a heavily contaminated acid mine drainage via an indigenous SRB consortium

“…A minor contribution from arsenite (As III -O bonding) was observed in the solids collected on filters at days 14 and 49 in the B1 experiment, and in the solids of the abiotic control. Such contribution could result from incomplete sulfidization of the large amount of arsenious acid initially present in the AMD (0.9 mmol/L,Table SI-3).Finally, EXAFS at the Zn K-edge showed that Zn was mainly present as amorphous ZnS, consistently with TEM-EDXS observation of ZnS nanoparticles (Figure SI-6) presenting shapes and sizes relevant for biogenic ZnS precipitation[45].…”

Drastic Change in Zinc Speciation during Anaerobic Digestion and Composting: Instability of Nanosized Zinc Sulfide

“…This could enhance sulfur reduction and hence the formation of nano-ZnS with the presence of sulfate reducing bacteria (SRB). [46][47][48] The second main Zn species in raw OWs was amorphous Zinc phosphate (Am-Zn-phosphate) which accounted for 22 to 84% of Zn species. This is in agreement with the high affinity of Zn for phosphate compounds.…”

“…46,51 The presence of SRB in liquid medium can also cause precipitation of nano-ZnS with crystalline defects. 47 The mechanism of SRB influence on nano-ZnS precipitation is not known and might be specific to SRB or an indirect mechanism. Indeed, organic compounds found in bacterial medium or synthesized by bacteria also influence the size of ZnS-particles.…”

Effect of nitrogen impurities on ZnS polymorphism

“…Sphalerite is a more common mineral, while wurtzite is less frequent. Sphalerite is also predominant in ZnS of biogenic origin [1,2]. Wurtzite is a high-temperature phase formed from sphalerite when heated to 1020 • C [3].…”

“…Other molecular dynamics studies show that wurtzite ZnS in vacuum is more stable in a nanoscale form [12], while wetting the surface with water leads to stabilization of sphalerite. A previous study [2] assumes that the interaction between the surface of biogenic ZnS nanoparticles with some peptides may contribute to the formation of a crystal with fewer defects due to a decrease in the polarity of the ZnS crystal surface. All these facts indicate a significant role of surface interactions in the formation of a ZnS crystalline structure of one or another type.…”