490-79-9Relevant articles and documents
Starovoitov et al.
, (1975)
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Senhofer,Sarlay
, p. 448 (1881)
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Formation of oxygen radicals in solutions of different 7,8- dihydropterins: Quantitative structure-activity relationships
Oettl, Karl,Pfleiderer, Wolfgang,Reibnegger, Gilbert
, p. 954 - 965 (2000)
Under certain conditions, 7,8-dihydroneopterin in aqueous solution promotes hydroxyl-radical formation. Thus, we investigated the stimulation of hydroxyl-radical formation by ten different 7,8-dihydropterins (=2-amino-7,8- dihydropteridin-4(1H)-one), i.e., 6-(1'-hydroxy) derivatives 1 and 2, methyl derivatives 3-7, and 6-(1'-oxo) derivatives 8-10. All but the 6-(1'-oxo) derivatives produced hydroxyl radicals, as measured by the amount of salicylic acid hydroxylation products. This amount was dependent on the stability of the dihydropterin used. In the presence of chelated iron ions, hydroxylation was increased in every case; even 6-(1'-oxo) derivatives showed a low hydroxylation of salicylic acid. The degree of increase, however, strongly depended on the side chain of the dihydropterin. The 7,8- dihydroneopterin (2) was investigated in more detail. Iron ions influenced both, the stability of 2 and hydroxyl-radical formation. While iron ions determined the kinetics of the reaction, the amount of 2 was responsible for the amount of hydroxyl radicals formed. Our data establish that promotion of hydroxyl-radical formation by 7,8-dihydropterins depends on the oxidizability of the dihydropterins and on their iron-chelating properties.
Black TiO2 nanotube arrays decorated with Ag nanoparticles for enhanced visible-light photocatalytic oxidation of salicylic acid
Plodinec, Milivoj,Gr?i?, Ivana,Willinger, Marc G.,Hammud, Adnan,Huang, Xing,Pan?i?, Ivana,Gajovi?, Andreja
, p. 883 - 896 (2018/11/10)
Novel forms of black TiO2 nanotubes-based photocatalysts for water purification were prepared. Two features were combined: decoration of TiO2 nanotube arrays with Ag nanoparticles (sample TiO2-NT's@Ag) and further hydrogenation of this material (TiO2-NT's@Ag-HA). Obtained photocatalysts show high efficiency for degradation of salicylic acid, a typical water-borne pollutant. The photocatalysts considerably exceed the photocatalytic properties of TiO2 nanotubes and commercial TiO2 P25 taken as a reference for modeling of the photocatalytic process. The comparison of photocatalytic activities between novel photocatalyst was based on a numerical approach supported by the complex kinetic model. This model allowed a separate study of different contributions on overall degradation rate. The contributions include: salicylic acid photolysis, photocatalysis in UVB, UVA and in the visible part of applied simulated solar irradiation. The superior photocatalytic performance of the photocatalyst TiO2-NT's@Ag-HA, particularly under visible irradiation, was explained by the combined effect of a local surface plasmon resonance (LSPR) due to Ag nanoparticles and creation of additional energy levels in band-gap of TiO2 due to Ti3+ states at nanotube surfaces. The presence of Ag also positively influence charge separation of created electron-holes pairs. The synergy of several effects was quantified by a complex kinetic model through the factor of synergy, fSyn. Stability testing indicated that the catalysts were stable for at least 20 h. The novel design of catalysts, attached on Ti foils, presents a solid base for the development of more efficient photocatalytic reactors for large-scale with a long-term activity.
Evidence for the electrochemical production of persulfate at TiO2 nanotubes decorated with PbO2
Santos, José Eudes L.,Antonio Quiroz, Marco,Cerro-Lopez, Monica,De Moura, Dayanne Chianca,Martínez-Huitle, Carlos A.
, p. 5523 - 5531 (2018/04/02)
It is well known that PbO2-based electrodes are considered to be non-active anodes, producing higher concentrations of hydroxyl radicals in aqueous solutions, and consequently, favouring the electrochemical degradation of organic pollutants. However, no evidence has been reported on the production of persulfates using this kind of electrode in sulphate aqueous solutions. For this reason, the aim of this work is to prepare (by an electrochemical procedure (anodization and electrodeposition)) and characterize (by X-ray diffraction, scanning electron microscopy, and potentiodynamic measurements) Ti/TiO2-nanotubes/PbO2 disk electrodes (with a geometrical area of 65 cm2) in order to evaluate the electrochemical production of persulfate using Na2SO4 solution as the support electrolyte and applying current densities of 7.5 and 60 mA cm-2, as well as the influence of the electrosynthesis of hydroxyl radicals, in concomitance. The results clearly showed that significant production of hydroxyl radicals and persulfate is achieved at the Ti/TiO2-nanotubes/PbO2 surface, but this depends on the current density. The production of OH at the Ti/TiO2-nanotubes/PbO2 surface in Na2SO4 solution was confirmed by a RNO spin trapping reaction. The results were compared with those of a Ti/Pt electrode in order to understand the effect when a lower amount of OH is produced at the active anode surface. Based on the results, the Ti/TiO2-nanotubes/PbO2 anode could exhibit good electrocatalytic properties for environmental applications involving persulfate oxidants.
