Photocatalytic degradation of molinate in aqueous solutions

• Published in: Environmental science and pollution research international 2014-11, Vol.21 (21), p.12294-12304
• Main Authors: Bizani, E., Lambropoulou, D., Fytianos, K., Poulios, I.
• Format: Article
• Language: English
• Subjects: Aliivibrio fischeri; Aquatic Pollution; Aqueous solutions; Atmospheric Protection/Air Quality Control/Air Pollution; Azepines - chemistry; Bacteria; By products; Byproducts; Catalysis; Chemistry; Chromatography, Liquid; Degradation; Detoxification; Dissolved organic carbon; Earth and Environmental Science; Ecotoxicology; Efficiency; Environment; Environmental Chemistry; Environmental Health; Environmental science; Herbicides; Herbicides - chemistry; Hydrogen peroxide; Hydrogen Peroxide - chemistry; Iron - chemistry; Kinetics; Mineralization; Molinate; Oxidation; Pesticides; Photocatalysis; Photodegradation; Photolysis; Pollution; Research Article; Semiconductors; Studies; Tandem Mass Spectrometry; Thiocarbamates - chemistry; Titanium - chemistry; Titanium dioxide; Toxicity; Vibrio fischeri; Waste Water Technology; Water Management; Water Pollutants, Chemical - chemistry; Water Pollution Control; Water Purification - methods
• ISSN: 0944-1344; 1614-7499
• DOI: 10.1007/s11356-014-3086-2

In this study, the degradation of molinate through heterogeneous photocatalysis, using two different types of the semiconductor TiO 2 as photocatalyst, as well as through homogeneous treatment, applying the photo-Fenton reaction, has been investigated. As far as heterogeneous photocatalysis is concerned, the degradation of the pesticide follows apparent first-order kinetics, while the type of the catalyst and the pH value of the solution affect the degradation rate. The effect of the addition of electron scavengers (H 2 O 2 and K 2 S 2 O 8 ) was also studied. In the case of photo-Fenton-assisted system, the degradation also follows pseudo-first-order kinetics. Parameters such as iron’s and electron scavenger’s concentration and inorganic ions strongly affect the degradation rate. The extent of pesticide mineralization was investigated using dissolved organic carbon (DOC) measurements. The toxicity of the treated solution was evaluated using the Microtox test based on the luminescent bacteria Vibrio fischeri . The detoxification and mineralization efficiency was found to be dependent on the system studied, and although it did not follow the rate of pesticide disappearance, it took place in considerable extent. The study of the photodegradation treatment was completed by the determination of the intermediate by-products formed during the process, which was carried out using LC-MS/MS technique and led to similar compounds with both processes.