Photoinduced Oxidation of Arsenite to Arsenate on Ferrihydrite

Bhandari, Narayan; Reeder, Richard J.; Strongin, Daniel R.

doi:10.1021/es103793y

Cited by 96 publications

(76 citation statements)

References 35 publications

(67 reference statements)

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“…The concentration of As(III) and goethite were chosen to ensure that the ratio of As to Fe (Fe/As z 100)after incubation was appropriate for the determination of the ratio of As(III) and As(V) by XANES analysis. In other studies on As(III) oxidation in the presence of iron oxides, the Fe/As ratio ranged from 5 to 580 (Ona-Nguema et al, 2005Bhandari et al, 2011Bhandari et al, , 2012. The flasks were shaken at 25 C at 150 rpm for 10 h. The adsorption reached equilibrium in 10 h. Abiotic control experiments of goethite only were also conducted.…”

Section: Effect Of Contact Order Of Bacteria and Goethite On The Oxidmentioning

confidence: 99%

The fate of arsenic adsorbed on iron oxides in the presence of arsenite-oxidizing bacteria

Zhang

Yin

et al. 2016

Chemosphere

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h i g h l i g h t sMicrobial cells lowered total As adsorption by minerals. Microbial oxidation proceeded much slowly in solid phase than in aqueous phase. Minerals with a higher affinity for As(III), hindered As(III) oxidation more. Under aerobic conditions, As(V) is the primary form in solid and aqueous phases. a b s t r a c t Arsenic (As) is a redox-active metalloid whose toxicity and mobility in soil depend on its oxidation state. Arsenite [As(III)] can be oxidized by microbes and adsorbed by minerals in the soil. However, the combined effects of these abiotic and biotic processes are not well understood. In this study, the fate of arsenic in the presence of an isolated As(III)-oxidizing bacterium (Pseudomonas sp. HN-1, 10 9 colonyforming units (CFUs)$ml À1 ) and three iron oxides (goethite, hematite, and magnetite at 1.6 g L À1 ) was determined using batch experiments. The total As adsorption by iron oxides was lower with bacteria present and was higher with iron oxides alone. The total As adsorption decreased by 78.6%, 36.0% and 79.7% for goethite, hematite and magnetite, respectively, due to the presence of bacteria. As(III) adsorbed on iron oxides could also be oxidized by Pseudomonas sp. HN-1, but the oxidation rate (1.3 mmol h À1 ) was much slower than the rate in the aqueous phase (96.2 mmol h À1 ). Therefore, the results of other studies with minerals only might overestimate the adsorptive capacity of solids in natural systems; the presence of minerals might hinder As(III) oxidation by microbes. Under aerobic conditions, in the presence of iron oxides and As(III)-oxidizing bacteria, arsenic is adsorbed onto iron oxides within the adsorption capacity, and As(V) is the primary form in the solid and aqueous phases. a r t i c l e i n f o

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Section: Effect Of Contact Order Of Bacteria and Goethite On The Oxidmentioning

confidence: 99%

The fate of arsenic adsorbed on iron oxides in the presence of arsenite-oxidizing bacteria

Zhang

Yin

et al. 2016

Chemosphere

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“…Therefore, microbial and photochemical processes are important in the environment because they can cause the reduction and/or oxidation of arsenic and iron Langner et al, 2000;Emett et al, 2001;Bhandari et al, 2011Bhandari et al, , 2012. Once iron oxide minerals are present, arsenic will adsorb onto these minerals and might undergo surface mediated reduction or oxidation reactions (Yan et al, 2008).…”

Section: Introductionmentioning

confidence: 99%

“…Abiotic oxidation of As(III) by dissolved oxygen is a possible mechanism of species transformation although the process is relatively slow (Zhao et al, 2011). Recent studies have shown that photoinduced oxidation of As(III) to As(V) can occur in the presence of nanoferrihydrite and goethite (Bhandari et al, 2011(Bhandari et al, , 2012. Bhandari et al (2011) assumed that in As(III)-ferrihydrite system, the oxidation of As(III) occurred on the ferrihydrite surface until the surface becomes saturated with As(V).…”

Section: Introductionmentioning

confidence: 99%

“…Recent studies have shown that photoinduced oxidation of As(III) to As(V) can occur in the presence of nanoferrihydrite and goethite (Bhandari et al, 2011(Bhandari et al, , 2012. Bhandari et al (2011) assumed that in As(III)-ferrihydrite system, the oxidation of As(III) occurred on the ferrihydrite surface until the surface becomes saturated with As(V). Bhandari et al (2011) also proposed that aqueous Fe (II) was formed from the reduction of Fe(III) associated with the iron oxide phases and the As(III) oxidation is similar under oxic and anoxic conditions.…”

Section: Introductionmentioning

confidence: 99%

“…Bhandari et al (2011) assumed that in As(III)-ferrihydrite system, the oxidation of As(III) occurred on the ferrihydrite surface until the surface becomes saturated with As(V). Bhandari et al (2011) also proposed that aqueous Fe (II) was formed from the reduction of Fe(III) associated with the iron oxide phases and the As(III) oxidation is similar under oxic and anoxic conditions. In the As(III)-goethite system, Bhandari et al (2012) cannot determine whether the oxidation of As (III) occurred on the goethite surface however higher amounts of As(III) oxidation is observed under oxic conditions than anoxic conditions.…”

Section: Introductionmentioning

confidence: 99%

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The Effect of Iron Oxide Nanoparticles on the Fate and Transformation of Arsenic in Aquatic Environments

Dickson¹

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A variety of dispersion techniques were investigated to disperse bare commercial IONPs. Vortex was able to disperse commercial hematite nanoparticles into unstable dispersions with particles in the micrometer size range while probe ultrasonication dispersed the particles into stable dispersions of nanometer size ranges for a prolonged period of time. Using probe ultrasonication and vortex to prepare IONPs suspensions of different particle sizes, the adsorption of arsenite and arsenate to bare hematite nanoparticles and hematite aggregates were investigated. To understand the difference in the adsorptive behavior, adsorption kinetics and isotherm parameters were determined.Both arsenite and arsenate were capable of adsorbing to hematite nanoparticles and vii hematite aggregates but the rate and capacity of adsorption is dependent upon the hematite particle size, the stability of the dispersion and the type of sorbed arsenic species.Once arsenic was adsorbed onto the hematite surface, both iron and arsenic can undergo redox transformation both microbially and photochemically and these processes can be intertwined. Arsenic speciation studies in the presence of hematite particles were performed and the effect of light on the redox process was preliminary quantified. The redox behavior of arsenite and arsenate were different depending on the hematite particle size, the stability of the suspension and the presence of environmental factors such as microbes and light. The results from this study are important and have significant environmental implications as arsenic mobility and bioavailability can be affected by its adsorption to hematite particles and by its surface mediated redox transformation.Moreover, this study furthers our understanding on how the particle size influences the interactions between IONPs and arsenic thereby clarifying the role of IONPs in the biogeochemical cycling of arsenic.

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Oxidation of Arsenite by Epoxy Group on Reduced Graphene Oxide/Metal Oxide Composite Materials

Shi

Jing

2020

Advanced Science

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Reduced graphene oxide/metal oxide (rGO/MO) hybrid has been widely used as a catalyst, while dissolved oxygen or radicals are generally recognized as the oxidant. This study finds that the adsorbed arsenite (As(III)) on rGO/MO is oxidized to arsenate (As(V)) in the absence of other oxidants or radicals. The oxidation of As(III) is observed on varying rGO/MOs, including rGO/MOs composited of different types of reduced graphene oxide (rGO) and metal oxide. The epoxy group on rGO acts as the oxidant, evidenced by the significant correlation between the consumption of epoxy group and oxidation of As(III). Meanwhile, metal oxide provides adsorption sites for As(III) during the adsorption–oxidation process. Based on a combination of spectroscopic measurements and computational calculation, a possible pathway for As(III) oxidation by rGO/MO is proposed: the oxygen atom in the epoxy group is bonded to the adsorbed As III O 3 , which is consequently oxidized to As V O 4 . Overall, this study proves the role of rGO/MO as an oxidant, which opens a new perspective on future studies using rGO/MO as a catalyst for the oxidation reaction.

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Photoinduced Oxidation of Arsenite to Arsenate on Ferrihydrite

Cited by 96 publications

References 35 publications

The fate of arsenic adsorbed on iron oxides in the presence of arsenite-oxidizing bacteria

The fate of arsenic adsorbed on iron oxides in the presence of arsenite-oxidizing bacteria

The Effect of Iron Oxide Nanoparticles on the Fate and Transformation of Arsenic in Aquatic Environments

Oxidation of Arsenite by Epoxy Group on Reduced Graphene Oxide/Metal Oxide Composite Materials

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