研究目的
To investigate the ultrasound-assisted photocatalytic degradation pathway of the herbicide Isoproturon in wastewater, comparing nanometric and micrometric TiO2 catalysts, and to identify degradation by-products and their ecotoxicity.
研究成果
Sonophotocatalysis with ultrasound power of 50 W cm?2 degrades 100% of Isoproturon in less than 1 hour, with Kronos 1077 being a valid alternative to P25 due to reduced health risks. The degradation pathway differs between photocatalysis and sonophotocatalysis, with the latter producing lower molecular weight by-products. However, coupling ultrasound with UV without a catalyst was detrimental, requiring further investigation. Future studies should explore catalyst reusability and the effects of dissolved salts.
研究不足
The study did not optimize the UV to ultrasound energy ratio, which could affect degradation efficiency. The use of tap water introduced matrix effects that were not fully characterized. pH was not controlled, which might influence degradation pathways. The reusability and stability of the catalysts were not investigated, and some by-product structures remained unidentified.
1：Experimental Design and Method Selection:
The study employed batch experiments in a thermostatic glass reactor to compare photolysis, sonolysis, sonophotolysis, and sonophotocatalysis. The rationale was to assess individual and combined effects of UV light and ultrasound on pollutant degradation, using different catalyst types and concentrations.
2：Sample Selection and Data Sources:
Synthetic wastewater solutions of Isoproturon (20 ppm) in distilled and tap water were used. Tap water from Milan was included to evaluate matrix effects.
3：List of Experimental Equipment and Materials:
Equipment included a thermostatic glass reactor, UVA lamp (Jelosil HG 500 W quartz with halides lamp), ultrasonic processor (VibraCell VCX 500, Sonics and Materials), HPLC-UV system (Agilent Technologies Microsorb MV 100–5 C18 column, Varian ProStar workstation), and LC-MS/MS system (Thermo Scientific Accela 600 HPLC coupled to Orbitrap LTQ XL mass spectrometer). Materials included Isoproturon (Sigma Aldrich PESTANALTM), TiO2 catalysts (Kronos 1077 and Degussa P25), HPLC-grade water and acetonitrile (Fischer Scientific).
4：Experimental Procedures and Operational Workflow:
For photocatalytic tests, 100 mL of IPU solution was irradiated with UVA light at 160 W m?2, with catalyst concentrations varied (0.05, 0.1, 0.2 g L?1). For ultrasonic tests, the ultrasonic probe was immersed 1 cm into the solution, with powers of 15, 25, and 50 W cm?2. Combined sonophotocatalytic tests were conducted similarly. Samples were taken periodically and analyzed.
5：05, 1, 2 g L?1). For ultrasonic tests, the ultrasonic probe was immersed 1 cm into the solution, with powers of 15, 25, and 50 W cm?Combined sonophotocatalytic tests were conducted similarly. Samples were taken periodically and analyzed.
Data Analysis Methods:
5. Data Analysis Methods: IPU degradation was monitored via HPLC-UV, and by-products were identified using LC-MS/MS. Data were processed with Thermo Xcalibur and MZmine 2 software, assuming first-order kinetics for degradation rates.
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