title: Photocatalytic degradation of eleven microcystin variants and nodularin by TiO2 coated glass microspheres.
abstract: 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 powder 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 min 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 min) was observed for the hydrophobic variants (microcystin-LY, -LW, -LF). Suitability of UV-LEDs as an alternative low energy light source was also evaluated.
authors.affiliation: Innovation, Design and Sustainability (IDeaS) Research Institute, Robert Gordon University, Riverside East, Garthdee Road, Aberdeen AB10 7GJ, UK.
authors.forename: Carlos J
authors.initials: CJ
authors.lastname: Pestana
authors.affiliation: Innovation, Design and Sustainability (IDeaS) Research Institute, Robert Gordon University, Riverside East, Garthdee Road, Aberdeen AB10 7GJ, UK.
authors.forename: Christine
authors.initials: C
authors.lastname: Edwards
authors.affiliation: Innovation, Design and Sustainability (IDeaS) Research Institute, Robert Gordon University, Riverside East, Garthdee Road, Aberdeen AB10 7GJ, UK.
authors.forename: Radhakrishna
authors.initials: R
authors.lastname: Prabhu
authors.affiliation: Centre for the Theory and Application of Catalysis (CenTACat), School of Chemistry and Chemical Engineering, Queen's University Belfast, David Keir Building, Stranmillis Road, Belfast BT9 5AG, UK. Electronic address: p.robertson@qub.ac.uk.
authors.forename: Peter K J
authors.initials: PKJ
authors.lastname: Robertson
authors.affiliation: Innovation, Design and Sustainability (IDeaS) Research Institute, Robert Gordon University, Riverside East, Garthdee Road, Aberdeen AB10 7GJ, UK.
authors.forename: Linda A
authors.initials: LA
authors.lastname: Lawton
mesh_terms: D002384:Catalysis; D000458:Cyanobacteria; D005898:Glass; D052998:Microcystins / Q000737:chemistry*; D008863:Microspheres; D010316:Particle Size; D010456:Peptides, Cyclic / Q000737:chemistry*; D055668:Photochemical Processes; D013056:Spectrophotometry, Ultraviolet; D014025:Titanium / Q000737:chemistry*; D014874:Water Pollutants, Chemical; D018508:Water Purification / Q000379:methods
chemical_list: D052998:Microcystins; D010456:Peptides, Cyclic; D014874:Water Pollutants, Chemical; C063998:nodularin; C009495:titanium dioxide; C078588:microcystin; D014025:Titanium
keywords: Blue–green algae; Cyanotoxins; Photospheres™; UV-LEDs; Water treatment