The effect of UV radiation on the efficiency phototransformation BPA in water in the presence of polypropylene superfine microfibers. The absorption and fluorescence spectra of the investigated substance with three types of PPM of various properties were obtained. After excitation with an excilamp, the main photoproduct BPA fluoresces in the region of 405 ÷410 nm. With an increase in the irradiation time from 0 to 10 minutes, an increase in the fluorescence intensity of this BPA photoproduct was recorded. This indicates that in the course of irradiation, effective photodegradation of the initial toxicant occurs and a photoproduct is formed. In the course of irradiation, the degradation of the resulting photoproducts occurs, which is associated with their adsorption on the surface of the PPM.
The study of short-lived induced (singlet-singlet) and long-lived induced (in particular, triplet-triplet) absorption capacity of crystal violet (CV) in various solvents was carried out by the pump-probe method. Water, dimethyl sulfoxide, isopropyl alcohol, and ethyl alcohol were selected as solvents. The formation of triplet states in various CV solvents was revealed upon excitation by nanosecond radiation of the 4th harmonic of a Nd: YAG laser (wavelength 266 nm, average power – 25.5 mV, repetition frequency – 3 Hz, pulse duration – 10 ns, peak power – 10-12 MW/cm2). It is shown that the spectrum of the induced CV absorption in ethanol contains two closely spaced bands at 400 and 485 nm. Short-lived and long-lived induced CV absorption in isopropanol at room temperature (λmax=400 nm) was recorded. Keywords: crystal violet (CV), induced absorption spectra, spectroscopy, pump-probe method.
The influence of irradiation wavelength on the degradation of Bisphenol A (BPA) in water under the action of KrCl and XeBr excilamp radiation in a photoreactor is investigated. Fluorescent photoproducts of photodegradation of the investigated molecule is constructed. In the work fluorescent photoproducts are defined. In an excited state BPA exists in a dimeric form at a concentration above 0.1 mM. After excitation by an excilamp the main BPA photoproduct fluoresces in the region of 420 nm. This behavior is explained by the fact that the action of 222 nm radiation leads to accumulation of a stable photoproduct. This product is destroyed as well as BPA after 120 minutes of exposure. Under the action of XeBr excilamp radiation a very stable product is formed with fluorescence at 380 nm. In order to establish the mechanism of BPA photolysis the product using chromatomass spectrometryfurther research is needed.
Results of theoretical research for two psoralen molecules: 8-methoxypsoralen and khellin are presented. Schemes of photophysical processes in psoralens based on quantum chemical calculation by the INDO method are analyzed. The rate constants of intersystem and internal conversions are calculated. We obtained rather high intersystem conversion constant that influences on the fluorescent yield of 8-methoxypsoralen (107 s-1) and an insignificant constant of intersystem conversion for khellin (103 s-1).
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