Bioleaching of arsenopyrite presents a great interest due to recovery of valuable metals and environmental issues. The current study aims to evaluate the arsenopyrite oxidation by Acidithiobacillus thiooxidans during 240h at different time intervals, in the presence and absence of supplementary arsenic. Chemical and electrochemical characterizations are carried out using Raman, AFM, SEM-EDS, Cyclic Voltammetry, EIS, electrophoretic and adhesion forces to comprehensively assess the surface behavior and biooxidation mechanism of this mineral. These analyses evidence the formation of pyrite-like secondary phase on abiotic control surfaces, which contrast with the formation of pyrite (FeS2)-like, orpiment (As2S3)-like and elementary sulfur and polysulfide (Sn(2-)/S(0)) phases found on biooxidized surfaces. Voltammetric results indicate a significant alteration of arsenopyrite due to (bio)oxidation. Resistive processes determined with EIS are associated with chemical and electrochemical reactions mediated by (bio)oxidation, resulting in the transformation of arsenopyrite surface and biofilm direct attachment. Charge transfer resistance is increased when (bio)oxidation is performed in the presence of supplementary arsenic, in comparison with lowered abiotic control resistances obtained in its absence; reinforcing the idea that more stable surface products are generated when As(V) is in the system. Biofilm structure is mainly comprised of micro-colonies, progressively enclosed in secondary compounds. A more compact biofilm structure with enhanced formation of secondary compounds is identified in the presence of supplementary arsenic, whereby variable arsenopyrite reactivity is linked and attributed to these secondary compounds, including Sn(2-)/S(0), pyrite-like and orpiment-like phases.
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http://dx.doi.org/10.1016/j.scitotenv.2016.05.143 | DOI Listing |
Anal Chem
November 2024
Shandong Key Laboratory of Environmental Processes and Health, School of Environmental Science and Engineering, Shandong University, Qingdao 266237, China.
Diffusive gradients in thin films (DGT) technique is renowned for passive sampling but not for rapid analysis, whereas surface-enhanced Raman spectroscopy (SERS) excels in ultrasensitive detection but is limited by substrate contamination from complex matrices. Here, a hierarchical nanostructure of silver (Ag) mirror-supported large Ag nanoparticles (∼120 nm) was grown in polyacrylamide hydrogel with a restricted pore size (PAM/Ag mirror/AgNPs) to serve as both the DGT binding phase and the SERS substrate. The substrate exhibited a maximum electric field enhancement factor of 9.
View Article and Find Full Text PDFToxicol Res
October 2024
Department of Genetic Engineering & Biotechnology, University of Dhaka, Dhaka, 1000 Bangladesh.
Environ Sci Pollut Res Int
September 2024
Transport Research Centre, Líšeňská 33a, Brno, 636 00, Czech Republic.
The present paper deals with an analysis of total arsenic concentration using ICP-MS/MS and an analysis of concentration of several arsenic species, arsenite (As), arsenate (As), monomethylarsonate (MMA), dimethylarsenite (DMA), and trimethylarsine oxide (TMAO), using HPLC-ICP-MS/MS in the PM fraction of airborne urban aerosol. The samples were collected during two campaigns, in the autumn of 2022 and in the winter of 2023, at three locations within the central European city of Brno, with the aim to evaluate the seasonal and spatial variations in the PM composition. The results confirmed only the seasonal variability in the content of the methylated arsenic species in PM influenced by biomethylation processes.
View Article and Find Full Text PDFCurr Epidemiol Rep
June 2024
National Institute of Environmental Health Sciences (NIEHS), Duram, North Carolina USA.
Food Chem Toxicol
June 2024
Department of Environmental Health Sciences, School of Public Health and Tropical Medicine, Tulane University, New Orleans, LA, USA. Electronic address:
Consumption of rice-based foods provides essential nutrients required for infants and toddlers' growth. However, they could contain toxic and excess essential elements that may affect human health. The study aims to determine the composition of rice-based baby foods in the USA and outside and conduct a multiple-life stages probabilistic exposure and risk assessment of toxic and essential elements in children.
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