Aeration, effect, degradation

Aeration, effect, degradation In water-soil system, 59t Aerial pesticide applicators, volume and characteristics of wastewater, 154t,196 Aerobic pathway, trlfluralln degradation, 39... 

Table I Summary of the Effect of Ambient Conditions, Aeration at 1 L/min, Peptone Nutrient at 0.1 Wt. %, Concentration, and the Presence of 5 Other Pesticides (Mix) on the Degradation of Six Pesticides and Two Decomposition Products... 

The effects of all combinations of aeration and nutrients are easily discernable on the right hand YES count column. The increase from 10 to 14 degradation units on a scale of 0 to 32 when aeration was incorporated must be weighed carefully against the cost of adding aeration to the containers. Nutrients had an inhibitory, if any, effect on pesticide degradation in general. 

When PCP solution (Id4 M) under continuous air bubbling is subjected to ultrasound effects, the characteristic absorption bands decrease and the treatment leads to a complex mixture of products. Carbon-chlorine bonds are rapidly cleaved, and after a 150-min sonication time, 90% of the chlorine is recovered in the solution as chloride ions. PCP transformation in aerated solution occurs together with nitrite and nitrate formation. Carbon dioxide is a product of PCP degradation, and it has long been recognized as an inhibitor for sonochemical reactions. 

The effect of the halogen substituent (fluoro, chloro, bromo and iodo) on the yield and mechanism of 4-halophenol photolysis was investigated by Durand et al. [24], Transient spectroscopy in aerated aqueous solutions indicated the formation of p-benzoquinone O-oxide from each derivative except 4-iodophenol for which no transients were detected p-benzoquinone and hydroquinone were found as photoproducts for all four compounds. It was concluded that the carbene mechanism was valid for the whole series. Under continuous irradiation, the 4-halophenol degradation quantum yields were determined to be

fluorescence lifetimes decreased in the same order, from 2.1 ns for 4-fluorophenol to 0.4 ns for 4-chlorophenol and < 0.1 ns for 4-bromophenol. 

---