Radiation-chemical Method Research Articles

Influence of annealing on the physicochemical properties of 2L ferrihydrite synthesized by radiation-chemical method from iron (III) nitrate

In this study, ferrihydrite (Fhy) nanoparticles (NPles) synthesized by the radiation chemical method (RCM) from an iron nitrate alcohol solution were annealed in air at temperatures ranging from 100 to 1200 ºC. The effects of annealing temperature on the phase transformation and basic physicochemical properties of the annealed Fhy nanopowders (NPs) were investigated. Fhy NPles annealed at 400 ºC and above can be converted to hematite NPles. The X-ray diffraction (XRD) pattern of the RCM-synthesized product corresponded to two-line (2 L) Fhy NPles, with no additional peaks, confirming their chemical purity. Up to 200 ºC, no significant phase transformation of Fhy NPles was observed; at 300 ºC, Fhy transformed into maghemite, which further transformed into hematite at 400 ºC. TEM/HRTEM analysis showed the formation of mesoporous agglomerates consisting of amorphous-crystalline NPles approximately 2 nm in size in the Fhy S95 sample annealed at 95 ºC. Selected area electron diffraction (SAED) images indicated the presence of two crystalline phases in sample S95: FeO and zero-valence Fe. The specific surface area (SSA) of mesoporous Fhy NPles varied non-monotonically between 100 and 500 ºC, peaking at 53.2 m2/g at 300 ºC. X-ray photoelectron spectroscopy (XPS) analysis revealed a minor nitrogen impurity, likely from the initial iron nitrate precursor, and a significant amount of adsorbed carbon on the developed porous surface of Fhy NPles. The phase composition of annealed Fhy samples correlated with their photoluminescent (PL) spectra. In samples S400 and S500 containing hematite, a small ferromagnetic contribution emerged, disrupting the linear magnetization-field dependence observed in samples S0-S200. Thus, the properties of 2 L Fhy nanoparticles produced by the radiation chemical method can be modified through thermal annealing while maintaining their potential biomedical applications as nanocontainers for drug delivery and contrast agents.

Cytotoxicity and antioxidant activity of iron oxide nanopowders synthesized by radiation-chemical method using different precursors

The study revealed a correlation between the cytotoxicity and antioxidant activity of iron oxide nanopowders produced by the radiation-chemical method and the choice of precursors (iron (III) nitrate or iron(II) sulfate), and the temperature of pre-annealing of the synthesized product, and also irradiation with accelerated electrons. Notably, high and lowabnormal cytotoxicity of aqueous suspensions of samples S300 and S400, respectively, annealed at temperatures of 300 and 400 °C, was observed for the first time at all concentrations (0.1–1.0 ml/mg). The likely cause of this abnormal cytotoxicity was identified as alterations in the textural and structural properties of NP after annealing.Furthermore, a significant impact of electron beam irradiation on the antibacterial and antioxidant properties of both unannealed and annealed iron oxide NP was discovered with irradiated samples exhibited lower cytotoxicity compared to non-irradiated ones. Additionally, the deposition of nanosilver on the surface of iron oxide powders was found to significantly influence their biological properties, with the survival of Vero cell cultures being dependent on the composite concentration in the aqueous suspension.A study of the oxidative stress of composites based on iron oxides coated with silver showed that they significantly increased cell viability, and at a concentration of 1 mg/ml provided complete mitigation of oxidative stress in cells.

Radiation-chemical synthesis and characterization of ferrihydrite from iron (III) nitrate

In this study, 2-line ferrihydrite (2L Fh) nanoparticles (NPles)were synthesized by radiation-chemical method from an alcoholic solution of iron (III) nitrate for the first time. The X-ray diffraction analysis confirmed that the synthetic powder exhibited the characteristic pattern of 2L Fh NPles. DSC-TG analysis conducted in air atmosphere further verified the formation of 2L Fh. SEM analysis showed the presence of mesoporous plate-like structures in the 2L Fh powder, consisting of aggregates of NPs with an average size of approximately 20 nm. The absence of impurity peaks on the X-ray diffractograms and energy dispersion spectra (EDX) confirmed the chemical purity of the produced 2L Fh NPles. Additionally, the XPS method detected the presence of nitrogen and carbon adsorbed to the developed surface of the 2L Fh plates. 2L Fh NPles, when dried in air at a temperature of 50 °C, rapidly dissolved in water. 2L Fh NPles alcohol suspensions were stabilized using surfactants polyethylenimine (PEI) and acetylacetone (AcAs). 2L Fh NPles showed good photocatalytic properties when irradiated with ultraviolet light of methyl violet (MV) dye. These 2L Fh NPles, synthesized using an environmentally friendly radiation-chemical method, have immense potential for applications in biomedicine and photocatalysis.

Effect of air annealing on properties of maghemite nanoparticles produced by radiation-chemical method

Amorphous-crystalline nanoparticles (NPles) of maghemite (γ-Fe2O3) were successfully prepared by a radiation-chemical method using a precursor-heptahydrate of iron (II) sulfate. Synthesized NPles were quasi-spherical agglomerates 200–300 nm in size with an uneven surface covered with thin, porous, randomly oriented, elongated plates of irregular shape, with sharp vertices. The amorphous component of NPles included ultra-fine NPles maghemite about 2 nm in size. Stepwise annealing of the original nanopowder (NP) in air showed a phase transformation of NPles along the following path: maghemite + amorph (RT-150 °C) →amorph (200–500 °C) →hematite (570–1050 °C). The hematite NP produced after annealing at a temperature of 575 °C showed good texture characteristics: the specific surface area (SSA) increased from 21 to 36.8 m2/g, the pore volume increased from 0.04 to 0.15 cm3/g, while maintaining the particle nanosize of not more than 38 nm. X-ray photoelectron spectroscopy (XPS) showed the presence of the following elements on the surface of the synthesized NPles –S, C, O, Fe and N (N only in the original sample S0) and increased O–Fe bond with an increase in annealing temperature. The paramagnetic properties of the studied NPles indicate the prospect of their use as contrast agents in magnetic resonance imaging (MRI).

Preparation of iron oxide nanopowders by the radiation-chemical method

Various magnetic nanopowders of iron oxide were obtained using the radiation-chemical method when irradiated with a nanosecond electron beam. The main physical and chemical characteristics of the prepared nanopowders were studied, such as structure, porosity, thermal resistance and magnetic properties. It was found that, by selecting precursors and the composition of the solution, it is possible to control not only the textural properties and yield of the obtained nanopowders (by changing the dose and dose rate intensity of the electron beam), but also to obtain crystalline or amorphous nanopowders, on which their magnetic properties depend.

Preparation of silver coated oxide nanomaterials and study of their properties

Annotation. Nanopowders of aluminum oxide silicon oxide and iron oxide with silver coating were produces by the radiation-chemical method. The dimensions of the nanoparticles were 50 to 80 nm, and the area can be changed from 2-3%, up to 40%. Was carried out the validation of antibacterial properties against E.coli and staphylococcus. Were estimated photocatalytic properties of nanopowders, which showed applications perspective as a photocatalytic agent. Cytotoxic properties were also investigated, which showed the relevance of the use of some the obtained composites for targeted drug delivery.

Preparation and properties of silver nanopowders and composites based on a radiation-chemical method

Silver nanopowders with specific surface area up to 39.1 cm2/g, as well as alumina powders coated with silver consisting of nanoparticles with sizes of 50 and 80 nm, were produced by a radiation-chemical method. The influence of the number of OH groups of polyhydric alcohols on the specific surface area of obtained silver nanopowders is shown in the first time. The coating area of the oxide base can be varied from 2-3%–40%. Antibacterial properties of the composite have been studied on wine yeast, as well as E. coli and S. aureus bacteria. The results of the study of photocatalytic properties of the composite showed its potential.

The Use of Size-Exclusion Chromatography for Determining the Sizes of Metal Nanoparticles Synthesized in Reverse Micelles

Size-exclusion chromatography has been employed to determine the sizes of palladium and silver nanoparticles synthesized by the radiation-chemical method in micellar solutions of a surfactant (AOT) at different degrees of hydration ω0 = [H2O]/[AOT]. Silver and palladium nanoparticle sizes are in the ranges of 1.5–5.3 and 1.5–3 nm. The results obtained have been compared with the data of atomic force microscopy. It has been shown that the sizes of nanoparticles synthesized in micellar solutions must be corrected with allowance for the contribution of micelle shell thickness.

Radiation-Chemical Reduction of Copper Ions in Nanoporous Matrices Based on High-Density Polyethylene

The effect of preliminary annealing of semicrsytalline high-density polyethylene films on the parameters of nanoporous structure formed during deformation of polymers in physically active liquid environments via the intercrystallite crazing has been studied. Optimal conditions providing the development of a stable open-cell polymeric materials with a high level of porosity (50%) and pore size below 10 nm have been elavorated. For the first time, the in situ reduction of copper ions into copper(0) in the pores of the highdensity polyethylene nanoporous polymer matrix has been carried out using the radiation-chemical reduction method. The reaction has led to the formation of nanoscale copper particles within the polymer, which makes it possible to produce metal-polymer nanocomposites with valuable functional properties.

Effect of counterpart metals in carbon-supported Pt-based catalysts prepared using radiation chemical method

The process of nanoparticle formation by radiation chemical synthesis in a heterogeneous system has been investigated. Carbon-supported Pt-based bimetallic nanoparticles were synthesized using a high-energy electron beam. Rh, Cu, Ru, and Sn were used as counterpart metals. The nanoparticles were characterized by inductively coupled plasma atomic emission spectrometry, transmission electron microscopy, X-ray diffraction, and X-ray absorption spectroscopy. PtRh formed a uniform random alloy nanoparticle, while Cu partially formed an alloy with Pt and the remaining Cu existed as CuO. PtRu formed an alloy structure with a composition distribution of a Pt-rich core and Ru-rich shell. No alloying was observed in PtSn, which had a Pt-SnO2 structure. The alloy and oxide formation mechanisms are discussed considering the redox potentials, the standard enthalpy of oxide formation, and the solid solubilities of Pt and the counterpart metals.

Irradiation route to aqueous synthesis of highly luminescent ZnSe quantum dots and its function as a copper ion fluorescence sensor

Size-controlled synthesis of stable ZnSe QDs with narrow distribution in aqueous environment through conventional soft chemical method still poses a challenge. The proposed radiation assisted strategy demonstrates aqueous synthesis of stable, monodisperse and luminescent ZnSe QDs capped with chelating ethylene diamine under ambient conditions and at room temperature. Radiation chemical method facilitates in slow and in-situ release of selenium ion from sodium selenosulfate. The concentrations of precursors, such as zinc salt, selenium source, ethylene diamine and absorbed radiation (7–90kGy) dose were optimized for obtaining good quality particles. Selective quenching of luminescence of as-synthesized quantum dots (QDs) by Cu2+ ions vis-à-vis other physiologically important cations provide evidence for use of ZnSe quantum dots as alternative to toxic Cd-based quantum dots to probe Cu2+ ions. The linear relation of ratio of loss in emission intensity as a function of concentration of Cu(II) indicates detection limit in nano-molar range.

Studies of adsorption of palladium nanoparticles on silicon oxide using methods of spectrophotometry and atomic force microscopy

In this work, the method of UV-VIS spectrophotometry was used to study the adsorption of palladium nanoparticles Pd NPs on silicon dioxide (silochrome S-120). Pd NPs were synthesized using a radiation-chemical method in micelle 0.15 M solutions of the AOT surfactant at different degrees of hydration ω0 = [H2O]/[AOT]. It is shown that adsorption depends on the structure of nanoparticles, conditions of synthesis in reverse micelles, including the ω0 value, which determines the NP size, as well as the chemical and physicochemical properties of the silochrome surface.

Synthesis and properties of nickel nanoparticles and their nanocomposites

For the first time, nickel nanoparticles are synthesized in reverse micelles by a radiation-chemical method. The particles are shown to be spherical with sizes of an order of magnitude of 1–100 nm. Nickel particles are oxidized by air oxygen to nickel oxide nanoparticles, retaining their shape and nanoscale dimensions. Adsorption of nickel-metal nanoparticles on silica is studied by spectrophotometry.

Involvement of proton transfer in the reductive repair of DNA guanyl radicals by aniline derivatives

The most easily oxidized sites in DNA are the guanine bases, and major intermediates produced by the direct effect of ionizing radiation (ionization of the DNA itself) are electron deficient guanine species. By means of a radiation chemical method (gamma-irradiation of aqueous thiocyanate), we are able to produce these guanyl radicals in dilute aqueous solutions of plasmid DNA where the direct effect would otherwise be negligible. Stable modified guanine products are formed from these radicals. They can be detected in the plasmid conversion to strand breaks after a post-irradiation incubation with a DNA base excision endonuclease enzyme. If aniline compounds are also present, the yield of modified guanines is strongly attenuated. The mechanism responsible for this effect is electron donation from the aniline compound to the guanyl radical, and it is possible to derive rate constants for this reaction. Aniline compounds bearing electron withdrawing groups (e.g., 4-CF3) were found to be less reactive than those bearing electron donating groups (e.g., 4-CH3). At physiological pH values, the reduction of a guanyl radical involves the transfer of a proton as well as of an electron. The mild dependence of the rate constant on the driving force suggests that the electron is not transferred before the proton. Although the source of the proton is unclear, our observations emphasize the importance of an accompanying proton transfer in the reductive repair of oxidative damage to guanine bases which are located in a biologically active double stranded plasmid DNA substrate.

INFLUENCE OF WOOD EXTRACTS ON THE UV CURING OF ACRYLATE COATINGS

ABSTRACT The effect of wood extracts on the kinetics of UV curing of an urethane diacrylate was studied by real-time FTIR spectroscopy. Whereas extracts from rose wood (Dalbergia latifolia) inhibit the reaction, curing is not significantly affected by extracts from teak wood (Tectona grandis). Data of the pendulum hardness of the coatings confirm these results. Moreover, the radical scavenging capacity of the extracts was determined relative to benzoquinone by a radiation-chemical method.

New radiation-chemical method for the removal of petroleum products from water

The possibility of water purification wih the removal of petroleum products present in the dissolved state, as an oil-in-water emulsion and as a film at the water surface by radiation-chemical treatment has been shown.

The regeneration of polluted activated carbon by radiation techniques

In this paper, the regeneration of used activated carbon from monosodium glutamate factory was experimented using radiation and acid-alkali chemical cleaning method. Results showed that the activated carbon saturated with pollutants can be wash away easily by flushing with chemical solution prior irradiation. DSC was used to monitor the change of carbon adsorption

Hydrated Electrons in a Quaternary Microemulsion System: A Pulse Radiolysis Study

Using the technique of pulse radiolysis, hydrated electrons have been produced and studied in quaternary microemulsion (sodium lauryl sulfate (NaLS)/water/cyclohexane/1-pentanol) system. Remarkably high lifetimes (∼20 μs) for hydrated electrons have been obtained. In general, these are two orders of magnitude higher than those reported earlier in reverse micelles. The water droplet sizes and location of the probes have been determined from the decay kinetics of hydrated electrons. The yields and half-lives (t1/2) of the hydrated electrons vary smoothly as the water droplet sizes are changed. We believe that these studies will be useful not only in interpreting electron transfer reactions occurring in small water pockets in biological systems but also in the production of metal nanoclusters by radiation chemical method.

Radiation-chemical method of gas purification from sulphur dioxide

The influence of high energies on a gas stream under certain conditions, may produce sulphuric acid. In this case a degree of gas purification of sulphur dioxide of up to 99% is obtained, and energy expenditure is 0.2–1.0 kW per 1 kg of final product. Describing these processes may be recommended as part of their future development and industrial and commercial realization.

Polystyrene thin film formed by synchrotron radiation chemical vapor deposition

Formation of polystyrene thin film by the synchrotron radiation chemical vapor-deposition method was investigated using a styrene monomer. Polystyrene film was deposited at the irradiated area and vicinity along the irradiated area on a Si substrate. The deposition rate depended on the monomer gas pressure, substrate temperature, and x-ray wavelength. Polystyrene film at the irradiated area was insoluble in benzene solvent, while that at the unirradiated area was easily dissolved. A patterned film deposition could be successfully performed under an irradiation of synchrotron radiation through a Ni mesh mask. The pattern profile was influenced by the gap length between the Si substrate and mask and a clear pattern was obtained after benzene treatment.