Concentration Of Nitric Acid Solution Research Articles

Influence of Liquid Type, Filler and Coupling Agent on the Interface Resistivity Between Silicone Rubber and Fiber Reinforced Plastic

The interface between silicone rubber (SR) and fiber reinforced plastic (FRP) is a weak point in composite insulator, which is easy to be affected by moisture. However, the corresponding evaluation methods and detection means are not complete yet. Based on the newly proposed method for measuring the interface resistivity with a four-electrode system, the influence of liquid type, filler and coupling agent on the interface resistivity are studied in this paper. It is found that the interface resistivity reduced by 2-4 orders of magnitude after permeation by deionized water, saline and low concentration nitric acid, but the variation trend of interface resistivity is specific when permeated in high concentration of nitric acid solution (1 mol/L). The experimental results of samples with and without silicone coupling agent (SCA) are compared and it is found that the interface without silane coupling agent is easier to be penetrated by liquid, and the change of interface resistivity is more obvious. Besides, the influence of moisture-sensitive Alumina Tri-hydrate and SiO2 fillers, which could provide paths for water and hydrated ions to permeate, on interface resistivity are analyzed. The experimental results are of great significance for the selection of the appropriate formula system and the prevention of liquid penetration for composite insulators.

PREPARATION AND PROPERTIES OF ORGANO-MINERAL FERTILIZER WITH PROLONGED ACTION, BASED ON THE ABIES BARK

The method of preparation of organo-mineral fertilizer with increased resistance to mineral components leaching by water, based on the impregnation of support from abies bark by water solution of potassium nitrate, zinc, copper and magnesium sulphates, was proposed. The dates about composition and properties of the porous support from abies bark were provided. The potassium nitrate contents (23.5 mass.%) and concentration of nitric acid solution (0.1 N) providing high water resistance of fertilizer were determined. I t was shown, that application of treatment by 0,1 N nitric acid allows reduce delete from fertilizer by water nitrogen in 2.4 times, and other mineral components – in 1.7–1.9 times. The ability of fertilizer to slow release of mineral components by water during long time was identified, that determined effect of his prolonged action. It was shown, that after treatment fertilizer by water at room temperature during 30 days from him leaching 64.8% potassium, 66.6% nitrogen, 70.3% magnesium, 65.2% copper и 65.3% zinc from their initial contents. The growth-stimulating effect of organo-mineral fertilizer based on the abies bark was shown by experiments on germination of wheat seed variety "Novosibirskaya 15".

Enhanced visible-light-driven photocatalytic performance of porous graphitic carbon nitride

In this study, a series of porous graphitic carbon nitride (g-C3N4) materials were fabricated through a direct pyrolysis of protonated melamine by nitric acid solution. These as-prepared porous samples were characterized by a collection of analytical techniques. It was found that a proper concentration of nitric acid solution involved facilitated to generate samples in tube-like morphology with numerous pores, identified with X-ray diffraction patterns, FT-IR spectra, SEM, TEM, and BET measurements. These g-C3N4 samples were subjected to photocatalytic degradation of dye Rhodamine B (RhB) in aqueous under visible-light irradiation. Under identical conditions, those porous g-C3N4 samples showed significantly improved catalytic performance in comparison with the sample prepared without the introduction of nitric acid. In particularly, the best candidate, sample M1:1, showed an apparent reaction rate nearly 6.2 times that of the unmodified counterpart. The enhancement of photocatalytic performance could be attributed to the favorable porous structure with the enlarged specific surface area and the suitable electronic structure as well. In addition, ESR measurements were conducted for the sake of proposing a photocatalytic degradation mechanism.

Solvent extraction separation of copper and zinc from MSWI fly ash leachates

Fly ash from combustion of municipal solid waste (MSW) contains significant amounts of metals, some of which are valuable and some of which are potentially toxic. This type of ash is most often stabilized and landfilled which means that the metals will be difficult to reclaim at a later stage. In recent years efforts have been made to develop feasible methods to recover selected metals, such as Zn, from MSW fly ash. If this would be possible, a significant amount of valuable metals could be re-inserted in the industrial material loops.This paper describes the development and evaluation of a process for recovery of Cu and Zn from MSW combustion fly ash based on hydrochloric acid leaching followed by two solvent extraction processes, one for each metal. The separation of Cu from the acid leachate was done using an aldoxime extractant, LIX860N-I, in kerosene and a mixture of phosphine oxides, Cyanex 923, also in kerosene, was used for extraction of Zn from the Cu-depleted aqueous phase. The extraction of Cu was selective, but a significant amount of other metals, such as Fe and Pb, were co-extracted together with Zn. It was shown that it is possible to decrease the contamination of Fe by using a suitable concentration of nitric acid solution for stripping or by removing the contaminating metals through cementation.The suggested process was tested for two MSW combustion fly ashes in laboratory scale experiments and gave Cu yields of 69–87% and Zn yields of 75–80% based on the contents in the ash.

Segmental nitrogen doping and carboxyl functionalization of multi-walled carbon nanotubes

Partial nitrogen doping was performed during the catalytic chemical vapor deposition (CCVD) synthesis of multi-walled carbon nanotubes. A special reactor was created to facilitate the execution of syntheses with different reaction conditions. The synthesized samples were analyzed by transmission electron microscopy (TEM) in order to provide information about the tubular and nontubular morphology of particles and their deformation gained after the reaction conditions were changed. The incorporation of nitrogen into the carbon structure was studied by X-ray photoelectron spectroscopy (XPS), whereas X-ray diffraction (XRD) and Raman spectroscopy evaluations showed the degree of graphitization. The samples then were carboxyl functionalized in varied concentrations of nitric acid solutions and photosynthetic reaction center protein (RC-26) purified from purple bacteria was linked to the carboxyl groups in order to make the degree of functionalization visible. The protein-linked samples were characterized by atomic force microscopy (AFM). Our experiments indicated that the syntheses carried out in the new reactor were successful and resulted in carbon nanotubes partially doped with nitrogen. TEM studies revealed that the expected deformations are localized only in a defined segment of carbon nanotubes therefore nitrogen doping is most possibly presented there. The nitrogen content in the samples represented in atomic ratios was between 0.9% and 2.9%. The deformations facilitate the functionalization at that certain area, thus the location of carboxyl groups can be determined.

Evaluation of etching on amorphous carbon films in nitric acid

Etching on hydrogenated amorphous carbon (a-C:H) films by nitric acid was evaluated in situ using surface plasmon resonance (SPR) device with a multilayer structure consisting of an a-C:H layer on Au. A flow cell was used to introduce the nitric acid onto the a-C:H top layer of the multilayer structure. Nitric acid solutions with various concentrations were injected into the flow cell. The SPR angle was determined as the angle with minimum reflectivity. The obtained SPR angle decreased with increasing duration of nitric acid injection into the flow cell. The observed behavior of the SPR angle indicated that the a-C:H film surface was etched by nitric acid. The thickness of the film was calculated from the SPR angle, and an etching rate of 3.21nm/h was obtained in the case of using 2.0M nitric acid. The obtained shift in the SPR angle depended on the concentration of nitric acid solution. These results indicate that in situ evaluation using the SPR device with a multilayer structure can be used to detect the etching of amorphous carbon films in a liquid.

Application of factorial designs for optimisation of on-line determination of cadmium, lead and nickel in welding fumes by atomic absorption spectrometry

A flow-injection flame atomic absorption spectrometric method using diluted nitric acid and ultrasound energy to assist metals acid leaching from welding fumes was optimised. Several variables were simultaneously studied by applying a Plackett-Burman design. Results showed that the statistically significant variables (95%) were concentration of nitric acid solution for cadmium, lead and nickel, ultrasonic water-bath temperature for lead and nickel, and sonication time for nickel. Factors such as ultrasonic water-bath temperature and sonication time were finally optimised by using a central composite design. Detection limits were 0.1, 1.0 and 3.4 µg m−3, and repeatability (n = 11) were 3.2, 1.9 and 1.6%, for cadmium, lead and nickel, respectively. The proposed method was applied to the determination of cadmium, lead and nickel in welders’ workplace environments.

Determination of Trace Amounts of Zinc in Welding Fumes by Flow‐Injection Flame Atomic Absorption Spectrometry

A flow‐injection flame atomic absorption spectrometric method for the determination of zinc in welding fumes has been developed. The method is based on the continuous ultrasound‐assisted dissolution of the zinc oxide collected on the air filter. Variables such as sonication time, nature and concentration of the acid solution used as dissolving solution, dissolution temperature, flow rate of the continuous manifold, and dissolving solution volume were simultaneously studied by applying a Plackett–Burman design. Results showed that only the concentration of nitric acid solution used as dissolving solution was a statistically significant variable (confidence interval of 95%). Factors such as dissolution temperature and sonication time were finally optimized by using a central composite design. The detection limit was 1.1 µg/m3 and the repeatability of the overall method is 1.6% (n=11) for a zinc concentration of 75.4 µg/m3. The proposed method was applied to the determination of zinc in welders' workplace environments. The authors were invited to contribute this paper to a special issue of the journal entitled “Spectroscopy and Automation”. This special issue was organized by Miguel de la Guardia, Professor of Analytical Chemistry at Valencia University, Spain.

Basic study of photochemistry for application to advanced nuclear fuel cycle technology

In this study, we have accomplished for the first time the photochemical valence adjustment of Pu and Np for the separation and coextraction of these elements in a nitric acid solution using UV light irradiation. Also, the separation and coextraction of Pu and Np were substantiated in principle by the solvent extraction using 30% TBP/n-dodecone after or during the photochemical valence adjustment. By only one photochemical separation operation, about 86% of Pu and about 99% of Np were distributed into the organic phase and the aqueous phase, respectively, and then by only one photochemical coextraction operation, about 86% of Pu was distributed together with about 99% of Np into the same organic phase. Based on these experimental data, we determined that the photochemical oxidation reaction was due to the photoexcted nitric acid species, ′NO 3 −. To confirm the strong oxidative ability of this species, the photochemical dissolution tests of UO 2 powder in a nitric acid solution by UV light irradiation were carried out. The irradiation rate and the concentration of nitric acid solution significantly effects the photochemical dissolution reaction, we have also accomplished for the first time the photochemical dissolution of UO 2 at room temperature.

Recovery of uranium from U3O8 irradiated with thermal neutrons

The extraction of uranium with different concentrations of HDEHP in n-hexane from varying concentrations of nitric acid solutions was investigated. Uranium in the organic phase was quantitatively stripped with a solution containing 8M H2SO4 and 6M HCl, the partition coefficient was determined by X-ray fluorescence and U. V. spectrophotometry. The assay of95Zr,95Nb,239Np and other gamma-emitters was made with a Ge(Li) detector coupled to a 4096 multichannel analyzer.

Optical and X‐ray Topographic Studies of Barium Fluoride Single Crystals

AbstractSingle crystals of synthetic barium fluoride have been cleaved along {111} planes and the freshly cleaved faces have been etched in (1 : 250) concentration of nitric acid solution. One to one correspondence of dislocation etch pits have been observed on matched pairs. The same crystal has been investigated using X‐ray topographic technique. By selecting 0222 and 0222 reflections and MoKα1 radiation, stereopair projection topographs have been obtained and critically compared with the optical micrograph. One‐to‐one correspondence between dislocation out crop images and dislccation etch pits have been established. Due to dislocation contrast, the outcrop of dislocation images have been observed with the associated dislocation etch pits. The orientation of the Burgers vectors of the dislocation lines have been identified using AgKα1 radiation with 1111, 1111 and 1111 reflections and the implications have been discussed.