ABSTRACT
The migration of excitation energy of a number of psoralen compounds has been studied. For this, the methods of induced absorption spectroscopy, stationary electron spectroscopy, fluorescence and phosphorescence, as well as quantum chemistry were used. A comparative photostability of psoralen was achieved by exposure to a XeCl excilamp irradiation (emission wavelength λem = 308 nm) with parameters Δλ = 5-10 nm, Wpeak = 18 mW/cm2, p = 8.1 J/cm3, f = 200 kHz, pulse duration 1 µs. It was found that the singlet-triplet transition played a major role in the migration of excitation energy into triplet states. Among all tested compounds, substances with an OCH3-group in the structure have the strongest effect on the spectral-luminescent characteristics.
ABSTRACT
In this study, degradation of naphthalene and anthracene in water using ultraviolet (UV) light in the presence of polypropylene microfibers (PPM) modified with TiO2 was investigated using fluorescence analysis. KrCl (λrad = 222 nm) and XeCl (λrad = 308 nm) excilamps were used in a photoreactor. Phototransformation was studied for compounds in the presence of PPMs modified with TiO2 particles. The results indicated that the toxicants concentration was reduced by two orders of magnitude in the presence of PPMs. This reduction was due to effective adsorption of naphthalene and anthracene from water onto the surface of the PPMs. Exposure to the toxicant-water-PPM system to UV light led to the formation of fluorescent photoproducts.
Subject(s)
Hydrocarbons, Aromatic/chemistry , Polypropylenes/chemistry , Water Pollutants, Chemical/chemistry , Anthracenes/chemistry , Fluorescence , Naphthalenes/chemistry , Photolysis , Ultraviolet RaysABSTRACT
The interaction of a number of phenolic compounds, being 'model fragments' of humic acids, with cadmium ions was investigated. The fluorescence quenching method was used to determine the complexation constants of these compounds with cadmium ions. It was established that bonding of phenolic compounds by cadmium ions at ÑÐ 7 is weak and reaches a maximum value of 15% for interaction with resorcinol. It was demonstrated that modification of humic acids by the mechanoactivation method increases by three times bonding of cadmium ions, which is caused by strengthening the acid properties of carboxyl and hydroxyl groups at the aromatic ring. Copyright © 2016 John Wiley & Sons, Ltd.
Subject(s)
Cadmium/chemistry , Fluorescence , Humic Substances , Phenols/chemistry , Hydrogen-Ion Concentration , Ions/chemistry , Molecular Structure , Spectrometry, FluorescenceABSTRACT
The photolysis of humic acids and phenols in water containing humic acids was investigated. Humic acids extracted from peat (Vasuygan Bog, Tomsk Region, Russian Federation) induce the phototransformation of 4-chlorophenol at 365 and 222 nm. Humic acids were characterized by UV-, fluorescence-, IR- and EPR-spectroscopy and laser-induced fluorescence. The influence of humic acids on the phototransformation of phenols in different irradiation conditions was investigated. Comparison of the data on mercury lamp irradiation showed that the most effective phenols degradation was observed under exposure to KrCl* exilamp light (lambda = 222 nm) in the presence of humic acids.
