search
for
 About Bioline  All Journals  Testimonials  Membership  News  Donations


International Journal of Environment Science and Technology
Center for Environment and Energy Research and Studies (CEERS)
ISSN: 1735-1472
EISSN: 1735-2630
Vol. 12, No. 6, 2015, pp. 1945-1956
Bioline Code: st15181
Full paper language: English
Document type: Research Article
Document available free of charge

International Journal of Environment Science and Technology, Vol. 12, No. 6, 2015, pp. 1945-1956

 en Understanding abiotic ferrihydrite re-mineralization by ferrous ions
Raghav, M.; Sáez, A. E. & Ela, W. P.

Abstract

In this work, we study the abiotic re-mineralization of ferrihydrite under reducing conditions, obtained by adding zero-valent iron (ZVI) to a suspension of ferrihydrite particles. Under similar conditions, the system (ferrihydrite and ZVI) proceeded along two different transformation pathways differentiated by whether a magnetic stirrer or an overhead stirrer was used for mixing. X-ray diffraction characterization of the solid products showed that magnetite was the sole product of ferrihydrite transformation when a magnetic stirrer was used, whereas both goethite and magnetite were formed when an overhead stirrer was used. The system also behaved differently in terms of transformation kinetics and amount of magnetite formed. The quantification of magnetite generated was performed using a procedure developed in this study. The role of four mechanisms was investigated to explain these observed differences, namely—(1) presence/absence of high local Fe2+ concentrations, (2) mechanical abrasion, (3) presence/absence of a magnetic field, and (4) presence/ absence of a crystalline ZVI surface. Ferrous ions are expected to be concentrated near the magnetic bead on the magnetic stirrer as opposed to a more dispersed distribution with the overhead stirrer. This mechanistic study concluded that the presence of high local Fe2+ concentrations in the system leads to magnetite formation and the absence of the same leads to mixed goethite/magnetite or magnetite-free systems. These findings have significant implications for the mobilization of arsenic from iron (III) hydroxides as the conditions move from oxidizing to reducing, such as often occurs in engineered landfills and natural carbon-rich sediments.

Keywords
Arsenic; Iron compounds; Phase transformation; Water treatment; Landfills

 
© Copyright 2015 - International Journal of Environment Science and Technology
Alternative site location: http://www.ijest.org

Home Faq Resources Email Bioline
© Bioline International, 1989 - 2017, Site last up-dated on 05-Dec-2017.
Site created and maintained by the Reference Center on Environmental Information, CRIA, Brazil
System hosted by the Internet Data Center of Rede Nacional de Ensino e Pesquisa, RNP, Brazil