Heterogeneous photocatalytic reduction of ferrate(VI) in UV‐irradiated titania suspensions: Role in enhancing destruction of nitrogen‐containing pollutants

Sharma, Virender K.; Winkelmann, Kurt; Krasnova, Yekaterina; Lee, Changyoul; Sohn, Mary

doi:10.1155/s1110662x0300031x

Cited by 19 publications

(16 citation statements)

References 42 publications

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“…Langmuir-Hinshelwood (L-H) model has been applied to describe the kinetics of heterogeneous reactions such as photocatalytic reaction in aqueous TiO 2 suspension by many researchers successfully (Alekabi et al, 1989;Turchi and Ollis, 1989;Lin et al, 1993;Ooka et al, 1999;Sharma et al, 2003). Since the photocatalytic reduction of Fe(VI) in the TiO 2 suspension is also a heterogeneous reaction, the L-H equation below would be a suitable model to describe the photocatalytic reduction of Fe(VI) in aqueous TiO 2 suspension under UV illumination:…”

Section: Resultsmentioning

confidence: 99%

Degradation of endocrine disrupting chemicals in aqueous solution by interaction of photocatalytic oxidation and ferrate (VI) oxidation

2007

Water Science and Technology

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In this study, the degradation of bisphenol A in aqueous suspension by interaction of photocatalytic oxidation and ferrate(VI) oxidation was investigated under different conditions. The results indicate that the formation of Fe(V) and Fe(IV) is in the photocatalytic reduction of Fe(VI) by electron (e cb -) on the surface of TiO 2 . The oxidation efficiency of the photocatalytic oxidation in the presence of Fe(VI) was much greater than that without. In addition, the decomposition of Fe(VI) under different conditions was also investigated. The results indicate that the Fe(VI) reduction was accelerated by photocatalytic reaction and the adsorption capacity of Fe(VI) on TiO 2 surface decreased as pH increased. The characteristics of solid potassium ferrate prepared were investigated by X-ray diffraction. It was found that the potassium ferrate solid has a tetrahedral structure with a space group of D2h (Pnma) and a = 7.705 Å, b = 5.863 Å, and c = 10.36 Å.

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Section: Resultsmentioning

confidence: 99%

Degradation of endocrine disrupting chemicals in aqueous solution by interaction of photocatalytic oxidation and ferrate (VI) oxidation

2007

Water Science and Technology

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“…A buffer solution consisting of phosphate and borate was used to maintain a solution pH of 9.0. The reduction rate of ferrate(VI) increased with increasing ferrate(VI) concentration at all ammonia concentrations and the initial rate(R) may be expressed by Eq (5) Next, the kinetic measurements of the photocatalytic reduction of ferrate(VI) in Fe(VI)-TiO 2 -UV-NCO -were carried out under anoxic conditions at pH 9.0 as a function of [NCO -], ferrate(VI), light intensity (I 0 ), and amount of TiO 2 suspensions (Sharma et al 2003;Winkelman et al 2008). The rate law can be expressed by Eq.…”

Section: Ammonia and Cyanatementioning

confidence: 99%

Ferrate(VI) enhanced photocatalytic oxidation of pollutants in aqueous TiO2 suspensions

Sharma

Graham

et al. 2009

Environ Sci Pollut Res

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Background, aim, and scope Photocatalytic oxidation using UV irradiation of TiO 2 has been studied extensively and has many potential industrial applications, including the degradation of recalcitrant contaminants in water and wastewater treatment. A limiting factor in the oxidation process is the recombination of conduction band electrons (ecb ) with electron holes (h + vb ) on the irradiated TiO 2 surface, thus in aqueous conditions the presence of an effective electron scavenger will be beneficial to the efficiency of the oxidation process. Ferrate (FeO 4 2-) has received much recent attention as a water treatment chemical since it behaves simultaneously as an oxidant and coagulant. The combination of ferrate (Fe(VI)) with UV/TiO 2 photocatalysis offers an oxidation synergism arising from the Fe(VI) scavenging of ecb and the corresponding beneficial formation of Fe(V) from the Fe(VI) reduction. This paper reviews recent studies concerning the photocatalytic oxidation of problematic pollutants with and without ferrate. Materials and methods The paper reviews the published results of laboratory experiments designed to follow the photocatalytic degradation of selected contaminants of environmental significance and the influence of the experimental conditions (eg. pH, reactant concentrations, dissolved oxygen). The specific compounds are as follows: ammonia, cyanate, formic acid, bisphenol-A, dibutyl-and dimethyl-phthalate, and microcystin-LR. The principal focus in these studies has been on the rates of reaction rather than on reaction pathways and products. Results The presence of UV/TiO 2 accelerates the chemical reduction of ferrate and the reduction rate decreases with pH owing to deprotonation of ferrate ion. For all the selected contaminant substances the photocatalytic oxidation rate was greater in the presence of ferrate and this was believed to be synergistic rather than additive. The presence of dissolved oxygen in solution reduced the degradation rate of dimethyl phthalate in the ferrate/photocatalysis system. In the study of microcystin-LR it was evident that an optimal ferrate concentration exists, whereby higher Fe(VI) concentrations above the optimum leads to a reduction in microcystin-LR degradation. In addition, the rate of microcystin-LR degradation was found to be strongly dependent on pH and was greatest at pH 6. Discussion The initial rate of photocatalytic reduction under different conditions was analysed using a Langmuirian form. Decrease in rates in the presence of dissolved oxygen may be due to competition between oxygen and ferrate as electron scavengers, and to non-productive radical species interactions. The reaction between ferrate(VI) and MCLR in the pH range of 6.0-10.0 is most likely controlled by the protonated Fe(VI) species, HFeO 4 -. Conclusions The photocatalytic oxidation of selected, recalcitrant contaminants was found to be significantly greater in the presence of ferrate, arising from the role of ferrate in inhibiting the h + vb -ecb pair recombination on TiO 2 su...

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“…It has been evaluated for water and wastewater treatment (Sharma 2004), oxidation of cyanide (Sharma et al 1998), phenols (Graham et al 2004), hydrogen sulfide (Sharma et al 1997), thiourea (Sharma et al 1999(Sharma et al , 2003, organic matter (Qu et al 2003), cyanotoxins (Xing et al 2002), surfactants (Eng et al 2005), with satisfactory results.…”

Section: (Sharmamentioning

confidence: 99%

Wastewater disinfection and organic matter removal using ferrate (VI) oxidation

Bandala

Miranda

Beltrán

et al. 2009

Journal of Water and Health

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Heterogeneous photocatalytic reduction of ferrate(VI) in UV‐irradiated titania suspensions: Role in enhancing destruction of nitrogen‐containing pollutants

Cited by 19 publications

References 42 publications

Degradation of endocrine disrupting chemicals in aqueous solution by interaction of photocatalytic oxidation and ferrate (VI) oxidation

Degradation of endocrine disrupting chemicals in aqueous solution by interaction of photocatalytic oxidation and ferrate (VI) oxidation

Ferrate(VI) enhanced photocatalytic oxidation of pollutants in aqueous TiO2 suspensions

Wastewater disinfection and organic matter removal using ferrate (VI) oxidation

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