The purpose of this study was to evaluate photodegradabilities of the following new low-nitrogen chelating agents: N-bis[(carboxymethoxy)ethyl]glycine (compound 1), N-bis[(1,2-dicarboxyethoxy)ethyl]glycine (compound 2) and N-bis[(1,2-dicarboxyethoxy)ethyl]aspartic acid (compound 3). At first photodegradation of these chelating agents as uncomplexed Na-compound 1–3 and Cu(II) complexes were tested, both in lake and distilled water, by exposing them to near-UV region radiation at the range of 315–400 nm. Uncomplexed Na-compounds 2 and 3 were selected to sunlight exposure experiments carried out in lake and distilled water. Compound 3 was also tested in sunlight as Cu and Ca complexes in both solutions. Photodegradation of Na6-compound 3 in distilled water was studied by exposing it to radiation at the wavelength of 253.7 nm. Photodegradation products were analysed by means of GC-MS (gas chromatography with mass selective detector).
The results demonstrated that compound 1 was quite photostable even as Cu complex while compounds 2 and 3 were found to be photodegradable. Over 90% reduction of compound 3 was achieved during one week and 80% reduction of compound 2 in two weeks' time when they were added as Na salt to lake water and exposed to sunlight. Compound 3 as Cu complex degraded totally in the sunlight in less than one week. In the case of compound 3, the degradation rate decreased depending on the counter cation in the order Cu > Na Ca. The study demonstrated that photodegradation of Na6-compound 3 does not result in total mineralization of the compound. A photodegradation pathway for Na6-compound 3 is proposed. 相似文献
Summary. HPLC analysis of secondary metabolites represents an efficient tool for the studying of plant chemical diversity under different
aspects: chemotaxonomy, metabolomics, adaptative responses to ecological factors, etc. Statistical analyses of HPLC databases,
e.g. correlation analysis between HPLC peaks, can reliably provide information on the similarity/dissimilarity degrees between
the chemical compounds. The similarities, corresponding to positive correlations, can be interpreted in terms of analogies
between chemical structures, synchronic metabolisms or co-evolution of two compounds under certain environment conditions,
etc. . In terms of metabolism, positive correlations can translate precursor-product relationships between compounds; negative
correlations can be indicative of competitive processes between two compounds for a common precursor(s), enzyme(s) or substrate(s).
Furthermore, the correlation analysis under a metabolic aspect can help to understand the biochemical origins of an observed
polymorphism in a plant species. With the aim of showing this, we present a new approach based on a simplex mixture design,
Scheffé matrix, which provides a correlation network making it possible to graphically visualise and to numerically model
the metabolic trends between HPLC peaks. The principle of the approach consisted in mixing individual HPLC profiles representative
of different phenotypes, then from a complete mixture set, a series of average profiles were calculated to provide a new database
with a small variability. Several iterations of the mixture design provided a smoothed final database from which the relationships
between the secondary metabolites were graphically and numerically analysed. These relationships were scale-dependent, namely
either deterministic or systematic: the first consisted of a monotonic global trend covering the whole variation field of
each metabolites’ pair; the second consisted of repetitive monotonic variations which gradually attenuated or intensified
along a global trend. This new metabolomic approach was illustrated from 404 individual plants of Astragalus caprinus (Leguminoseae), belonging to four chemical phenotypes (chemotypes) on the basis of flavonoids analysed in their leaves. After
smoothing, the relationships between flavonoids were numerically fitted using linear or polynomial models; therefore the co-response
coefficients were easily interpreted in terms of metabolic affinities or competitions between flavonoids which would be responsible
of the observed chemical polymorphism (the four chemotypes). The statistical validation of the approach was carried out by
comparing Pearson correlations to Spearman correlations calculated from the smoothed and the crude HPLC database, respectively.
Moreover, the signs of the smoothed relationships were finely supported by analogies and differences between the chemical
structures of flavonoids, leading to fluent interpretation in relation to the pathway architecture. 相似文献
ZnBiYO4 was synthesized by a solid-state reaction method for the first time. The structural and photocatalytic properties of ZnBiYO4 were characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy and UV–Vis diffuse reflectance.ZnBiYO4 crystallized with a tetragonal spinel structure with space group I41/A. The lattice parameters for ZnBiYO4 were a = b = 11.176479 and c = 10.014323 . The band gap of ZnBiYO4 was estimated to be 1.58 e V. The photocatalytic activity of ZnBiYO4 was assessed by photodegradation of methyl orange under visible light irradiation. The results showed that ZnBiYO4 had higher catalytic activity compared with N-doped Ti O2 under the same experimental conditions using visible light irradiation. The photocatalytic degradation of methyl orange with ZnBiYO4 or N-doped Ti O2 as catalyst followed first-order reaction kinetics, and the first-order rate constant was 0.01575 and 0.00416 min-1for ZnBiYO4 and N-doped Ti O2, respectively. After visible light irradiation for 220 min with ZnBiYO4 as catalyst, complete removal and mineralization of methyl orange were observed. The reduction of total organic carbon, formation of inorganic products, SO2-4and NO-3, and evolution of CO2 revealed the continuous mineralization of methyl orange during the photocatalytic process. The intermediate products were identified using liquid chromatography–mass spectrometry. The ZnBiYO4/(visible light) photocatalysis system was found to be suitable for textile industry wastewater treatment and could be used to solve other environmental chemical pollution problems. 相似文献