Sonochemical substrate selectivity and reaction pathway of systematically substituted azo compounds.
The sonochemical degradation of the systematically substituted azo compound 2,7-dihydroxy-1-phenylazonaphthaline-3,6-disulfonic acid was investigated using a frequency of 850 kHz and an acoustic input power of 61 W. All derivatives were degraded completely within 6h by the ultrasonic treatment. Trifluoromethyl substituted azo compounds exhibited 2-3-fold higher degradation rates in comparison to the reference hydrogen substituted azo compound (k=0.54 h(-1)). In contrast to enzymatic processes (azoreductase or laccase), the ultrasonic treatment for these ortho-, meta-, and para-substituted azo compound showed 1.5-50-fold higher degradation rates. Additionally the ultrasound treatment was characterized by shorter reaction times. As a result of the detection and identification of specific intermediates using LC-MS a reaction pathway of the sonochemical degradation of the analysed azo compound is proposed indicating the formation of cyclohexadienone and naphthalene quinone derivatives.
Rehorek
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A
University of Applied Sciences Cologne, Faculty 09, Institute of Chemical Engineering and Plant Design, Betzdorfer Strasse 2, D-50679 Cologne, Germany. astrid.rehorek@fh-koeln.de <astrid.rehorek@fh-koeln.de>
Hoffmann
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P
Kandelbauer
A
A
Gübitz
G M
GM
D001391:Azo Compounds / Q000737:chemistry*; D007220:Industrial Waste / Q000032:analysis*; D009282:Naphthalenesulfonates / Q000737:chemistry*; D013010:Sonication; D014465:Ultrasonics
D001391:Azo Compounds; D007220:Industrial Waste; D009282:Naphthalenesulfonates