N. M. Bazhin

Bio: N. M. Bazhin is an academic researcher from Russian Academy of Sciences. The author has contributed to research in topics: Flash photolysis & Radical. The author has an hindex of 10, co-authored 22 publications receiving 333 citations. Previous affiliations of N. M. Bazhin include Novosibirsk State University.

Photolysis of sulfosalicylic acid in aqueous solutions over a wide pH range

Abstract: Nanosecond laser flash photolysis, absorption and fluorescent spectroscopy were used to study the influence of pH on the photophysical and photochemical processes of 5-sulfosalicylic acid (SSA) in aqueous solutions. Information on the excited singlet state intramolecular proton transfer (ESIPT) of the SSA ions could be deduced from the dependence of the quantum yield and the spectral maximum of SSA fluorescence on the pH of the medium. The main photochemical active form of SSA at pH < 10 is the dianion (HSSA 2− ). Excitation of this species gives rise to the HSSA 2− triplet state, to the SSA •2− radical anion and to the hydrated electron. In a neutral medium, the main decay channels of these intermediates are T–T annihilation, recombination and capture by the HSSA 2− dianion, respectively. A decrease of pH leads to an increase of the second-order rate constants of disappearance of both HSSA 2− triplet state and SSA •2− radical anion due to their protonation.

Photochemistry of Fe(III) and sulfosalicylic acid aqueous solutions

Abstract: Femtosecond and nanosecond laser flash photolysis was used to determine the photophysical and photochemical processes in aqueous solutions of Fe(III) ion and 5-sulfosalicylic acid (SSA) containing the FeSSA complex and the free ligand. Excitation of the FeSSA complex in the charge transfer band (λmax = 505 nm) is followed by an ultrafast relaxation to the ground electronic state with two characteristic times of 0.26 and 1.8 ps. The shorter time constant is ascribed to internal conversion to the vibrationally hot electronic ground state of FeSSA and the 1.8 ps time constant is assigned to the vibrational cooling of the ground state. The UV irradiation of the solution (308 nm) leads to the excitation of both the free ligand and the FeSSA complex. The latter relaxes rapidly and the free ligand undergoes intersystem crossing to the triplet state. This system undergoes an irreversible photochemical reaction originating from an electron transfer (k = (9 ± 2) × 108 M−1 s−1) from the free ligand in the triplet state to the FeSSA complex. This electron transfer is accompanied by an energy transfer between these species (k = (1.3 ± 0.2) × 109 M−1 s−1).

Mechanism of Fe(OH) 2+ (aq) photolysis in aqueous solution(Technical Report)

Abstract: Experiments on laser flash photolysis (308 nm) of Fe(OH) 2 + (aq) complex in aqueous solution with addition of nitrobenzene demonstrate the formation of hydroxyl radical in the primary photochemical process.

Pulsed laser photolysis of the PtCl62−—creatinine system in methanol

Abstract: The pulsed laser photolysis (excimer laser, XeCl; 308 nm) of the PtCl 6 2− —creatinine—methanol system was studied. The formation of an intermediate Pt III species (PtCl 5 2− cr, where cr = creatinine) was demonstrated and its decay kinetics were examined. Some kinetic and thermodynamic data of the photoinduced reaction were determined. The photolysis of the same system using stationary irradiation was also investigated allowing the end product of the reaction to be determined.

Photodegradation of tetracycline and formation of reactive oxygen species in aqueous tetracycline solution under simulated sunlight irradiation

Abstract: The photochemical kinetics and mechanism of the antibiotic compound tetracycline (TC) was investigated in aqueous solution under simulated sunlight irradiation. The study of the electron spin resonance revealed that the singlet oxygen (O-1(2)) was generated and the formation rate decreased with increasing pH in illuminated TC solution. Also, it was found that the H2O2 was produced and increased with increasing pH under the simulated sunlight irradiation. The results verified that TC could be sunlight excited and induced the formation of reactive oxygen species. Moreover, the contributions of oxidation reaction to photodegraclation of TC were clarified by the role of different radical scavengers. The kinetic model elucidated the involvement of TC photoinduced singlet oxygen on the photodegradation of TC. It was verified that the photodegradation of TC was predominantly attributed to direct photolysis. The quantum yields of direct photolysis increases with increasing pH in the range of 6.0-9.0, varying from 3.4 x 10(-4) to 1.1 x 10(-2). The indirect photolysis of TC was carried out in the presence of nitrate, bicarbonate, ferric ions and humic acid (HA), respectively. The results verified that the photodegradation of tetracycline was not obviously affected by these photosensitizers except ferric ions, indicating that the direct photolysis of TC was predominant process. (c) 2007 Elsevier B.V. All rights reserved.

Reactive photoinduced species in estuarine waters. Characterization of hydroxyl radical, singlet oxygen and dissolved organic matter triplet state in natural oxidation processes

Abstract: This paper describes the reactive photo-induced species (RPS) hydroxyl radical (HO˙), singlet oxygen (1O2) and chromophoric dissolved organic matter triplet state (3CDOM*) in fresh water (Canal Fumemorte) and estuarine water (Vaccares), sampled in the Camargue region, southern France. Experiments were conducted with a medium-pressure Hg lamp in a glass photoreactor (λ > 290 nm, 220 W m−2 irradiance between 290 and 400 nm). Steady-state concentration and initial production rate of RPS were determined for HO˙ and for 1O2. HO˙ and 1O2 were indirectly identified in the presence of benzene and furfuryl alcohol, respectively, as specific probes. The steady-state measured concentration of HO˙was (1.72 ± 0.01) × 10−16 M and (9.41 ± 0.12)×10−17 M for Vaccares and Canal waters samples, respectively, and the respective concentrations of 1O2 was (2.06 ± 0.22) × 10−13 M and (5.44 ± 0.04) × 10−14 M. The interference of 3CDOM* or other species in the determination of 1O2 with furfuryl alcohol, and of 1O2 in the quantification of 3CDOM* with 2,4,6-trimethylphenol was also quantitatively assessed. We developed a kinetic model describing the solar photo-transformation of xenobiotic organic compounds induced by the three different photooxidants HO˙, 1O2 and 3CDOM*.

Insight on the fundamentals of advanced oxidation processes. Role and review of the determination methods of reactive oxygen species

Abstract: Advanced oxidation processes (AOPs) have known increased application to treat wastewaters containing recalcitrant compounds that are hardly degraded by conventional technologies. AOPs are characterized by the formation of strong oxidants such as hydroxyl radicals, superoxide anions, hydroperoxyl radicals and singlet oxygen, which react with the contaminant, contributing to its degradation. This paper provides an overview of the determination methods of reactive oxygen species, ROS, in the application of AOPs; the methods developed in the available literature for the detection and quantification of ROS are reviewed as a first step in the assessment and detailed description of the mechanisms involved in the oxidation reactions, focusing on the critical analysis of the main strengths and weaknesses presented by the probe molecules employed in the evaluated studies. © 2015 Society of Chemical Industry

Light-Responsive Iron(III)–Polysaccharide Coordination Hydrogels for Controlled Delivery

Abstract: Visible-light responsive gels were prepared from two plant-origin polyuronic acids (PUAs), alginate and pectate, coordinated to Fe(III) ions. Comparative quantitative studies of the photochemistry of these systems revealed unexpected differences in the photoreactivity of the materials, depending on the polysaccharide and its composition. The roles that different functional groups play on the photochemistry of these biomolecules were also examined. Mannuronic-rich alginates were more photoreactive than guluronic acid-rich alginate and than pectate. The microstructure of alginates with different mannuronate-to-guluronate ratios changed with polysaccharide composition. This influenced the gel morphology and the photoreactivity. Coordination hydrogel beads were prepared from both Fe–alginate and Fe–pectate. The beads were stable carriers of molecules as diverse as the dye Congo Red, the vitamin folic acid, and the antibiotic chloramphenicol. The photoreactivity of the hydrogel beads mirrored the photoreactivi...