The mineralisation of methamidophos using ionised AN air water treatment pilot system and ultraviolet irradiation.
The degradation of methamidophos in pure bi-distilled water (with initial concentration 5 mg L(-1), pH = 7 at the beginning) was studied. For the first time, 2 ionised air water treatment pilot systems (IAPS-1, -2, no additives) were set up (Figs. 1 and 2). The degradation of methamidophos was carried out with only the IAPS-2 and with two different ultraviolet (UV) lamps: high- and low-pressure mercury lamps (HP and LP, with or without H202). The kinetics of these oxidative processes was investigated. The highest rate constant was reached by the LP, 0.2% H2O2 (k = 0.7524min(-1), t 1/2 = 0.9min), followed closely by both treatments with the HP, 0.2% H202 (k = 0.6328min(-1), t 1/2 = 1.1 min) and LP, 0% H202 (k = 0.4749min(-1), t 1/2 = 1.5 min). The lowest rate constants were achieved from the HP, 0% H202 process (k = 0.0303min(-1), t 1/2 = 22.9min) and from the IAPS-2 (k = 0.0117 min(-1), t 1/2 = 59.2min). The mineralisation of methamidophos was confirmed by the determination of the anions produced including NO3-, PO4(3-) and SO4(2-) during and at the end of each experiment. The toxicity of water samples before, during and after the experiments was tested with Daphnia test.
Hung
Dang Quang
DQ
Department of Chemistry, AG Thiemann, Institute of Physical and Environmental Chemistry, University of Bremen, Germany. dang@uni-bremen.de
Wohlers
Jens
J
Thiemann
Wolfram
W
D000390:Air Ionization; D000818:Animals; D002852:Chromatography, Ion Exchange; D003621:Daphnia / Q000187:drug effects; D008401:Gas Chromatography-Mass Spectrometry; D007700:Kinetics; D008903:Minerals / Q000737:chemistry; D009946:Organothiophosphorus Compounds / Q000737:chemistry* / Q000494:pharmacology / Q000528:radiation effects*; D010084:Oxidation-Reduction; D010865:Pilot Projects; D013997:Time Factors; D014466:Ultraviolet Rays; D018508:Water Purification / Q000379:methods*
D008903:Minerals; D009946:Organothiophosphorus Compounds; C014655:methamidophos