title: Photocatalysis of S-metolachlor in aqueous suspension of magnetic cerium-doped mTiO2core-shell under simulated solar light.
abstract: Magnetic cerium-doped mesoporous titanium dioxide was synthesized by combining sol-gel method and calcination using tetrabutanate and ammonium cerium nitrate as precursors and Pluronic P123 as a template coating on iron oxide covered with carbon in ethanol. The magnetic Ce-doped catalyst showed only anatase structure with a slight increase in lattice parameters compared to the undoped catalyst. The Ce LIII-edge X-ray absorption near-edge spectroscopy (XANES) spectra showed Ce3+, and the cerium substitution doping into titanium dioxide was proposed. Degradation of S-metolachlor in aqueous magnetic photocatalyst suspension followed (pseudo) first-order kinetics in the presence of 0.5 g L-1of γ-Fe2O3@C@0.16 mol% Ce-mTiO2with a half-life of 55.18 ± 1.63 min. Fifteen degradation products were identified, and their transformation routes of the photocatalytic degradation were then proposed. Complementary toxicity assessment of the treated S-metolachlor solution was undertaken with Environment Canada's algal microplate assay measuring growth inhibition (72-h IC50) in the freshwater chlorophyte Pseudokirchneriella subcapitata. This test method revealed a significant decrease in toxicity (1.7-fold reduction after 180 min of irradiation treatment), thereby confirming that the by-products formed following photocatalysis would be less harmful from an environmental point of view. Photocatalytic degradation of S-metolachlor thus appears to hold promise as a cost-effective treatment technology to diminish the presence of this herbicide in aquatic systems.
authors.affiliation: Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science, Kasetsart University, Bangkok, 10903, Thailand.
authors.forename: J
authors.initials: J
authors.lastname: Mermana
authors.affiliation: Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science, Kasetsart University, Bangkok, 10903, Thailand. fscipws@ku.ac.th.
authors.forename: P
authors.initials: P
authors.lastname: Sutthivaiyakit
authors.affiliation: Centre Saint-Laurent, Water Science and Technology Directorate, Environment Canada, 105 McGill, Montréal, Québec, H2Y 2E7, Canada.
authors.forename: C
authors.initials: C
authors.lastname: Blaise
authors.affiliation: Centre Saint-Laurent, Water Science and Technology Directorate, Environment Canada, 105 McGill, Montréal, Québec, H2Y 2E7, Canada.
authors.forename: F
authors.initials: F
authors.lastname: Gagné
authors.affiliation: Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science, Kasetsart University, Bangkok, 10903, Thailand.
authors.forename: S
authors.initials: S
authors.lastname: Charnsethikul
authors.affiliation: Synchrotron Light Research Institute (Public Organization), 111 University Avenue, Muang District, Nakhon Ratchasima, 30000, Thailand.
authors.forename: P
authors.initials: P
authors.lastname: Kidkhunthod
authors.affiliation: Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science, Ramkhamhaeng University, Bangkok, 10240, Thailand.
authors.forename: S
authors.initials: S
authors.lastname: Sutthivaiyakit
mesh_terms: D000081:Acetamides / Q000737:chemistry*; D002384:Catalysis; D002563:Cerium / Q000737:chemistry*; D006207:Half-Life; D008027:Light; D060526:Magnetic Fields; D055668:Photochemical Processes; D014025:Titanium / Q000737:chemistry*
chemical_list: D000081:Acetamides; C009495:titanium dioxide; D002563:Cerium; D014025:Titanium; C051786:metolachlor
keywords: Algal toxicity; Magnetic cerium-doped mesoporous titanium dioxide; Photocatalysis; Pseudokirchneriella subcapitata; S-metolachlor