Unveiling New Degradation Intermediates/Pathways from the Photocatalytic Degradation of Microcystin-LR

Antoniou, Maria G.; Shoemaker, Jody A.; Cruz, Armah A. de la; Dionysiou, Dionysios D.

doi:10.1021/es801637z

Cited by 163 publications

(123 citation statements)

References 41 publications

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“…Consequently the removal of these toxins during water treatment is a key concern. The photocatalytic destruction of cyanotoxins using TiO2, particularly microcystin-LR, has been studied in detail and reported to be a very effective process for removal of these toxins from water [1][2][3][4][5][6][7][8][9].…”

Section: Introductionmentioning

confidence: 99%

Photocatalytic degradation of eleven microcystin variants and nodularin by TiO2 coated glass microspheres

Pestana

Edwards

Prabhu

et al. 2015

Journal of Hazardous Materials

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Microcystins and nodularin are toxic cyanobacterial secondary metabolites produced by cyanobacteria that pose a threat to human health in drinking water. Conventional water treatment methods often fail to remove these toxins. Advanced oxidation processes such as TiO2 photocatalysis have been shown to effectively degrade these compounds. A particular issue that has limited the widespread application of TiO2 photocatalysis for water treatment has been the separation of the nanoparticulate power from the treated water. A novel catalyst format, TiO2 coated hollow glass spheres (Photospheres™), is far more easily separated from treated water due to its buoyancy. This paper reports the photocatalytic degradation of eleven microcystin variants and nodularin in water using Photospheres™. It was found that the Photospheres™ successfully decomposed all compounds in 5 minutes or less. This was found to be comparable to the rate of degradation observed using a Degussa P25 material, which has been previously reported to be the most efficient TiO2 for photocatalytic degradation of microcystins in water.Furthermore, it was observed that the degree of initial catalyst adsorption of the cyanotoxins depended on the amino acid in the variable positions of the microcystin molecule. The fastest degradation (2 minutes) was observed for the hydrophobic variants (microcystin-LY, -LW, -LF). Suitability of UV-LEDs as an alternative low energy light source was also evaluated.

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Section: Introductionmentioning

confidence: 99%

Photocatalytic degradation of eleven microcystin variants and nodularin by TiO2 coated glass microspheres

Pestana

Edwards

Prabhu

et al. 2015

Journal of Hazardous Materials

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“…This suggests that H 2 O 2 may be selective for cyanobacteria in mixed phytoplankton assemblages (Barrington and Ghadouani, 2008;Barroin and Feuillade, 1986). Hydrogen peroxide also forms hydroxyl and hydroperoxyl radicals which destroy the toxicity of cyanotoxins, such as microcystins, by inducing oxidative cleavage (Antoniou et al, 2008).…”

Section: Introductionmentioning

confidence: 99%

Cyanobacterial and microcystins dynamics following the application of hydrogen peroxide to waste stabilisation ponds

Barrington

Ghadouani

Ivey

2013

Hydrol. Earth Syst. Sci.

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Abstract. Cyanobacteria and cyanotoxins are a risk to human and ecological health, and a hindrance to biological wastewater treatment. This study investigated the use of hydrogen peroxide (H 2 O 2 ) for the removal of cyanobacteria and cyanotoxins from within waste stabilization ponds (WSPs). The daily dynamics of cyanobacteria and microcystins (commonly occurring cyanotoxins) were examined following the addition of H 2 O 2 to wastewater within both the laboratory and at the full scale within a maturation WSP, the final pond in a wastewater treatment plant. Hydrogen peroxide treatment at concentrations ≥ 0.1 mg H 2 O 2 µg −1 total phytoplankton chlorophyll a led to the lysis of cyanobacteria, in turn releasing intracellular microcystins to the dissolved state. In the full-scale trial, dissolved microcystins were then degraded to negligible concentrations by H 2 O 2 and environmental processes within five days. A shift in the phytoplankton assemblage towards beneficial Chlorophyta species was also observed within days of H 2 O 2 addition. However, within weeks, the Chlorophyta population was significantly reduced by the re-establishment of toxic cyanobacterial species. This re-establishment was likely due to the inflow of cyanobacteria from ponds earlier in the treatment train, suggesting that whilst H 2 O 2 may be a suitable short-term management technique, it must be coupled with control over inflows if it is to improve WSP performance in the longer term.

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“…Atrazine, methyl tert-butyl ether (MTBE), 1,4-dioxane, cis-dichlorethene (DCE) and 1,1,1-trichlorethane) (Table A1) were chosen as model compounds because they exhibit different susceptibilities to photolysis and AOPs. Atrazine and cis-DCE can both be photolysed and they are targets for selective oxidation by sulfate radicals, due to their π-electrons in their double bonds (Antoniou et al, 2008;Antoniou et al, 2010b;Waldemer et al, 2007). MTBE and 1,4 dioxane are typically difficult treatment targets for most conventional water treatment methods and therefore are typically mentioned as target chemicals for UVC/H 2 O 2 (Burbano et al, 2002;Stefan and Bolton, 1998), while 1,1,1-trichlorethane is known to be resilient to chemical oxidation (Li et al, 2013;Nelson et al, 1990).…”

Section: The Low Selectivity Of Homentioning

confidence: 99%

“…Free radicals are atoms or molecules that have unpaired valance electrons (odd number of electrons), which makes them particularly reactive. They can be stabilized by taking electrons from nearby compounds through e -abstraction, and reactions of addition, substitution, oxidation, and bond cleavage (Antoniou et al, 2008;Antoniou et al, 2010b;Li et al, 2013;Stefan and Bolton, 1998). Hydroxyl radicals (HO • ) are the most commonly used radicals in drinking water treatment because of their low selectivity and high reactivity with organic compounds (Buxton et al, 1988).…”

Section: Introductionmentioning

confidence: 99%

“…• as the primary or secondary oxidizing specie including light and heat activation of hydrogen peroxide (H 2 O 2 ), TiO 2 photocatalysis, sonication, and ozonolysis (Antoniou et al, 2008;Buxton et al, 1988). Commercial applications of the UV/ H 2 O 2 system such as the ones found at PWN, Netherlands and the Aurora Reservoir of the Orange Country, CA, USA, ran at 5-6 mg/L H 2 O 2 and around 0.7 to 0.8 kWh/m 3 -water-treated used for UV light (Kruithof et al, 2007;Linden and Rosenfeldt, 2011).…”

Section: Introductionmentioning

confidence: 99%

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Comparison of UVC/S2O82− with UVC/H2O2 in terms of efficiency and cost for the removal of micropollutants from groundwater

Antoniou

Andersen

2015

Chemosphere

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Highlights Cost comparison of UVC/HP and UVC/PS for groundwater treatment.  UVC/PS performed better for atrazine removal in Milli-Q water.  UVC/HP had a better overall performance for the removal of the mixture of contaminants.  Results from the collimated beam apparatus were comparable to the flow-through system.  UVC/PS is economically feasible for special matrices where selective oxidation is required. Graphical Abstract 2 AbstractThis study compared the UVC/S 2 O 8 2-system with the more commonly used AOP in water industry, UVC/H 2 O 2 , and examined whether the first one can be an economically feasible alternative technology. Atrazine and 4 volatile compounds (methyl tert-butyl ether, cisdichlorethen, 1,4-dioxane and 1,1,1-trichloroethane) were chosen as model contaminants because they exhibit different susceptibility to UVC photolysis and AOPs. A collimated beam apparatus was utilized for the majority of the experiments (controlled environment, without mass transfer phenomena), while selected experiments were performed in a flow-through reactor to simulate industrial applications. Initial experiments on the activation of oxidants with a LP lamp indicated that S 2 O 8 2-is photolysed about 2.3 times faster than H 2 O 2 and that the applied treatment times were not sufficient to utilize the majority of the oxidant. The effect of oxidants' concentrations were tested with atrazine alone and in the micropollutants' mixture and it was decided to use 11.8 mg/L S 2 O 8 2-and 14.9 mg/L H 2 O 2 for further testing since is closer to industrial applications and to minimize the residual oxidant concentration. Changes of the matrix composition of the treated water were investigated with the addition of chloride, bicarbonate and humic acids at concentrations relevant to a well-water-sample, the results showed that the system least affected was UVC/H 2 O 2 . Only when bicarbonate was used, UVC/S 2 O 8 2-performed better. Overall, testing these systems with the mixture of micropollutants gave better insights to their efficiency than atrazine alone and UVC/S 2 O 8 2-is recommended for selective oxidation of challenging matrices.

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Unveiling New Degradation Intermediates/Pathways from the Photocatalytic Degradation of Microcystin-LR

Cited by 163 publications

References 41 publications

Photocatalytic degradation of eleven microcystin variants and nodularin by TiO2 coated glass microspheres

Photocatalytic degradation of eleven microcystin variants and nodularin by TiO2 coated glass microspheres

Cyanobacterial and microcystins dynamics following the application of hydrogen peroxide to waste stabilisation ponds

Comparison of UVC/S2O82− with UVC/H2O2 in terms of efficiency and cost for the removal of micropollutants from groundwater

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