Improved ZnS nanoparticle properties through sequential NanoFermentation
Sequential NanoFermentation (SNF) is a novel process which entails sparging microbially produced gas containing H2S from a primary reactor through a concentrated metal-acetate solution contained in a secondary reactor, thereby precipitating metallic sulfide nanoparticles (e.g., ZnS, CuS, or SnS). SNF holds an advantage over single reactor nanoparticle synthesis strategies, because it avoids exposing the microorganisms to high concentrations of toxic metal and sulfide ions. Also, by segregating the nanoparticle products from biological materials, SNF avoids coating nanoparticles with bioproducts that alter their desired properties. Herein, we report the properties of ZnS nanoparticles formed from SNF as compared with ones produced directly in a primary reactor (i.e., conventional NanoFermentation, or “CNF”), commercially available ZnS, and ZnS chemically synthesized by bubbling H2S gas through a Zn-acetate solution. The ZnS nanoparticles produced by SNF provided improved optical properties due to their smaller crystallite size, smaller overall particle sizes, reduced biotic surface coatings, and reduced structural defects. SNF still maintained the advantages of NanoFermentation technology over chemical synthesis including scalability, reproducibility, and lower hazardous waste burden.
KeywordsSparging H2S-bearing gas Metal sulfide formation Average crystallite size Particle size Optical property
The authors gratefully acknowledge support from the US Department of Energy (DOE), Office of Energy Efficiency & Renewable Energy’s Advanced Manufacturing Office, Low Temperature Material Synthesis Program (CPS 24762) of the Manufacturing Demonstration Facility. Part of this research was conducted at the Center for Nanophase Materials Sciences, which is sponsored by the ORNL Scientific User Facilities Division and DOE Office of Basic Research Sciences. EM characterization (JRE and EMP) was supported by the Office of Biological and Environmental Research (BER), Office of Science, DOE as part of the Mercury Science Focus Area at ORNL. The authors thank Deanne Brice for C&N analysis. FTIR work by M K was supported by the US DOE, Office of Science, Basic Energy Sciences under Award ERKCC96. ORNL is managed by UT-Battelle, LLC, for DOE under contract DE-AC05-00OR22725.
Mention of brand name products does not constitute an endorsement by the U.S. Geological Survey. The data in this manuscript represent the entirety of the experimental work conducted.
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Conflict of interest
Portions of this work may be subject to United States Application No. 62/359,356 filed on July 7, 2016 and WO2018009739A1 published on January 11, 2018 issued to inventors including coauthors JWM, TJP, RSO, DEG, INI, CBJ, GGJ, MKK, PCJ, and BLA. This article does not contain any studies with human participants or animals.
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