title: Ultrasound based AOP for emerging pollutants: from degradation to mechanism.
abstract: Ultrasound is known to degrade organic compounds by pyrolysis and by the reaction of free radicals. In this work, sonolytic degradation of an identified water pollutant, coomassie brilliant blue (CBB), has been carried out in pure water as well as in river water. In the case of pure water, 90 % degradation was obtained after 30 min of sonication (350 kHz frequency, 60 W power), whereas in river water, the same efficiency was achieved only after 90 min. The degradation was also performed in the presence of varying concentration of (10-100 mg L-1) inorganic ions such as chloride, sulfate, nitrate, bicarbonate, and carbonate ions which were detected in the river water sample. Higher concentration of chloride enhanced the degradation due to the salting out mechanism. The enhancement of degradation in the presence of nitrate is mainly due to the change in the surface potential at the interface of the cavitating bubble. Bicarbonate ion and carbonate ion enhanced the degradation due to the involvement of carbonate radicals. A possible degradation mechanism is proposed based on the product profile determined by LC-Q-ToF-MS. The low efficiency of degradation in river water compared to that in pure water is likely due to the increased rate of bubble dissolution or escape of bubbles (degassing effect), and the scavenging of•OH by the organic content (high chemical oxygen demand (COD)).
authors.affiliation: School of Environmental Sciences, Mahatma Gandhi University, Kottayam, 686560, Kerala, India.
authors.forename: Manoj P
authors.initials: MP
authors.lastname: Rayaroth
authors.affiliation: Advanced Centre of Environmental Studies and Sustainable Development, Mahatma Gandhi University, Kottayam, 686560, Kerala, India.
authors.forename: Usha K
authors.initials: UK
authors.lastname: Aravind
authors.affiliation: School of Environmental Sciences, Mahatma Gandhi University, Kottayam, 686560, Kerala, India. cta@mgu.ac.in.|Inter University Instrumentation Centre, Mahatma Gandhi University, Kottayam, 686560, Kerala, India. cta@mgu.ac.in.
authors.forename: Charuvila T
authors.initials: CT
authors.lastname: Aravindakumar
mesh_terms: D057919:Biological Oxygen Demand Analysis; D002254:Carbonates / Q000737:chemistry; D002712:Chlorides / Q000737:chemistry; D009566:Nitrates / Q000737:chemistry; D010084:Oxidation-Reduction; D045483:Rivers / Q000737:chemistry; D012394:Rosaniline Dyes / Q000737:chemistry* / Q000302:isolation & purification; D013010:Sonication; D013431:Sulfates / Q000737:chemistry; D000069453:Ultrasonic Waves; D014867:Water / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000737:chemistry* / Q000302:isolation & purification; D018508:Water Purification
chemical_list: D002254:Carbonates; D002712:Chlorides; D009566:Nitrates; D012394:Rosaniline Dyes; D013431:Sulfates; D014874:Water Pollutants, Chemical; D014867:Water; C004692:coomassie Brilliant Blue
keywords: Advanced oxidation processes; COD reduction; Cavitation; Degradation pathway; Inorganic ions; Triphenylmethane dyes; Ultrasound