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Scott Fendorf

Bio: Scott Fendorf is an academic researcher from Stanford University. The author has contributed to research in topics: Arsenic & Ferrihydrite. The author has an hindex of 79, co-authored 244 publications receiving 21035 citations. Previous affiliations of Scott Fendorf include University of California, Berkeley & Oak Ridge National Laboratory.


Papers
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Journal ArticleDOI
TL;DR: In this paper, the authors used Extended X-ray absorption fine structure (EXAFS) spectroscopy to deduce the local coordination environment of two environmental contaminants, arsenate and chromate, on the mineral goethite (α-FeOOH).
Abstract: The molecular structure of ions retained on mineral surfaces is needed to accurately model their sorption process and to determine their stability. Extended X-ray absorption fine structure (EXAFS) spectroscopy was used in this study to deduce the local coordination environment of two environmental contaminants, arsenate and chromate, on the mineral goethite (α-FeOOH). Based on the oxyanion−Fe distances, it was concluded that three different surface complexes exist on goethite for both oxyanions: a monodentate complex, a bidentate-binuclear complex, and a bidentate-mononuclear complex. At low surface coverages, the monodentate complex was favored while at higher coverages the bidentate complexes were more prevalentthe bidentate-binuclear complex appears to be in the greatest proportion at these highest surface coverages. Therefore, modeling efforts for chromate or arsenate retention on goethite need to consider a monodentate complex at very low coverages, both the monodentate and bidentate complexes at in...

992 citations

Journal ArticleDOI
28 May 2010-Science
TL;DR: In this article, the transport of arsenic and key reactants such as organic carbon that could trigger release in zones with presently low groundwater arsenic levels is investigated in rural areas throughout the major river basins draining the Himalayas.
Abstract: Over the past few decades, groundwater wells installed in rural areas throughout the major river basins draining the Himalayas have become the main source of drinking water for tens of millions of people Groundwater in this region is much less likely to contain microbial pathogens than surface water but often contains hazardous amounts of arsenic--a known carcinogen Arsenic enters groundwater naturally from rocks and sediment by coupled biogeochemical and hydrologic processes, some of which are presently affected by human activity Mitigation of the resulting health crisis in South and Southeast Asia requires an understanding of the transport of arsenic and key reactants such as organic carbon that could trigger release in zones with presently low groundwater arsenic levels

967 citations

Journal ArticleDOI
TL;DR: In this paper, the adsorption and stability of arsenite on goethite (α-FeOOH) was investigated using a combination of standard batch techniques and X-ray absorption spectroscopy (XAS).
Abstract: The adsorption and stability of arsenite [As(III)] on goethite (α-FeOOH) was investigated using a combination of standard batch techniques and X-ray absorption spectroscopy (XAS). The reactivity of As(III) with α-FeOOH at varying pH and As(III) concentration provided macroscopic evidence for strong complexation on the α-FeOOH surface. Extended X-ray absorption fine structure (EXAFS) spectroscopy gave an average As(III)−Fe interatomic distance of 3.378 ± 0.014 A, which is indicative of bidentate binuclear bridging As(III) complexes on the α-FeOOH surface and which is similar to other oxyanions which adsorb on α-FeOOH by an inner-sphere mechanism. X-ray absorption near-edge structure (XANES) analysis indicated that the As(III)−α-FeOOH surface complex is stable toward heterogeneous oxidation to As(V), as determined by the energy position of the X-ray absorption edge. The structural information from EXAFS was included in the description of As(III) adsorption on the α-FeOOH surface using a surface complexation...

785 citations

Journal ArticleDOI
01 Jun 1995-Geoderma
TL;DR: In this paper, surface reactions that influence chromium chemistry in soils are described, e.g., adsorption of Cr(III) and Cr(VI) on goethite, along with interfacial redox reactions, and the influences of organic chelates on these reactions are also detailed.

614 citations

Journal ArticleDOI
TL;DR: In this article, the authors investigated the pathways and mechanisms of secondary mineralization during dissimilatory iron reduction by a common iron-reducing bacterium, Shewanella putrefaciens (strain CN32), of 2-line ferrihydrite under advective flow conditions.

599 citations


Cited by
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TL;DR: The scale of the problem in terms of population exposed to high As concentrations is greatest in the Bengal Basin with more than 40 million people drinking water containing ‘excessive’ As as mentioned in this paper.

6,741 citations

Journal ArticleDOI
TL;DR: Strong acids and bases seem to be the best desorbing agents to produce arsenic concentrates, and some commercial adsorbents which include resins, gels, silica, treated silica tested for arsenic removal come out to be superior.

3,168 citations

Journal ArticleDOI
TL;DR: In this paper, a synthesis of the use of selected trace elements as proxies for reconstruction of paleoproductivity and paleoredox conditions is presented, and the combined used of U, V and Mo enrichments may allow suboxic environments to be distinguished from anoxic-euxinic ones.

2,708 citations

Journal ArticleDOI
TL;DR: The sorption data indicate that, under most of the chemical conditions investigated in this study, reduction of As(V) in the presence of HFO or goethite would have only minor effects on or even decrease its mobility in the environment at near-neutral pH conditions.
Abstract: Arsenic derived from natural sources occurs in groundwater in many countries, affecting the health of millions of people. The combined effects of As(V) reduction and diagenesis of iron oxide minerals on arsenic mobility are investigated in this study by comparing As(V) and As(III) sorption onto amorphous iron oxide (HFO), goethite, and magnetite at varying solution compositions. Experimental data are modeled with a diffuse double layer surface complexation model, and the extracted model parameters are used to examine the consistency of our results with those previously reported. Sorption of As(V) onto HFO and goethite is more favorable than that of As(III) below pH 5−6, whereas, above pH 7−8, As(III) has a higher affinity for the solids. The pH at which As(V) and As(III) are equally sorbed depends on the solid-to-solution ratio and type and specific surface area of the minerals and is shifted to lower pH values in the presence of phosphate, which competes for sorption sites. The sorption data indicate tha...

2,115 citations

Journal ArticleDOI
16 Jun 2010-ACS Nano
TL;DR: The magnetite-graphene hybrids show a high binding capacity for As(III) and As(V), whose presence in the drinking water in wide areas of South Asia has been a huge problem.
Abstract: Magnetite−graphene hybrids have been synthesized via a chemical reaction with a magnetite particle size of ∼10 nm. The composites are superparamagnetic at room temperature and can be separated by an external magnetic field. As compared to bare magnetite particles, the hybrids show a high binding capacity for As(III) and As(V), whose presence in the drinking water in wide areas of South Asia has been a huge problem. Their high binding capacity is due to the increased adsorption sites in the M−RGO composite which occurs by reducing the aggregation of bare magnetite. Since the composites show near complete (over 99.9%) arsenic removal within 1 ppb, they are practically usable for arsenic separation from water.

1,806 citations