Decomposition Of Impurities Research Articles

Removal and Decomposition of Impurities in Wastewater From the HyBRID Decontamination Process of the Primary System in a Nuclear Power Plant

Decontamination wastewater generated from the HyBRID decontamination process of the primary system in a nuclear power plant contains impurities such as sulfate ions, metal ions containing radioactive nuclides, and hydrazine (carcinogenic agent). For this reason, it is necessary to develop a technology to remove these impurities from the wastewater to a safe level. In this study, it has been conducted to remove the impurities using a decontamination wastewater surrogate, and a treatment process of the HyBRID decontamination wastewater has been established. The performance and applicability of the treatment process have been verified through 1 L scale of replicates and a pilot scale (300 L/batch) test.

Efficient purification of Al30 by organic complexation method

A method was developed for preparing high purity Al30O8(OH)56(H2O)2418+ (Al30) through elimination of impurities by complexation. Polyaluminum chloride II (PAC30) with Alc content of 75% was adopted as the source of Al30. The PAC30 was prepared under conditions of total aluminum concentration 0.1 mol/L and OH−/Al ratio 2.2 to obtain the highest content of Al30. A precipitation/metathesis method, organic solvent precipitation method and organic complexation method were examined to separate and purify Al30. It was found that only by the organic complexation method could high purity Al30 products be obtained in large yield economically. In the experiments, benzoic acid was used as the coordinating reagent to decompose the main impurity AlO4Al12(OH)24(H2O)127+ (Al13), and the Al30 product could be obtained by precipitation and metathesis operations. It was noteworthy that the decomposition of impurities by benzoic acid could be completed in 2 hr. The Al30 product was characterized by Ferron assay, 27Al-NMR, SEM, XRD and TGA. The results showed that the purity of the Al30 product could exceed 92%.

ІЧ-СПЕКТРОМЕТРИЧНІ ТА ТЕРМОГРАВІМЕТРИЧНІ ДОСЛІДЖЕННЯ КОМПЛЕКСІВ КОБАЛЬТУ, КУПРУМУ ТА ЦИНКУ НА ОСНОВІ ГЛІФОСАТУ

The complexes with Co(II), Cu(II) and Zn(II) based on glyphosate (N-phosphonomethylglycine) have been synthesized and studied by means of IR-, electron diffusion spectroscopies, thermogravimetric and elemental analysis. The coordination behavior between glyphosate and carbacylamidophosphates was compared. By means of IR spectroscopy, it was found that regardless of the ratio of reacting components (metal salt and glyphosate) the coordination compounds of the same type for each metal are always formed. The spectrum of the glyphosate and complexes with it can be divided into two parts, corresponding to the different donor groups of the ligand. Between 1500 and 1800 cm-1 strong peaks are found, mostly associated with stretching motions of the carboxylate group, while the region 800–1200 cm-1 is dominated by peaks originating from the phosphonate. The changes in frequencies of phosphate P–O (Δ(PО)=127 cm-1 for Na4CuL2, 144 cm-1 for Na4CоL2 and 21 cm-1 for ZnHL); NH– and C=O (Δ(CО)=102 cm-1 for Na4CuL2, 133 cm-1 for Na4CоL2, and 123 cm-1 for ZnHL) peaks indicate the involvement of these groups in coordination. The ν(C–O)a is shifted to higher frequency and broadened. The thermal decomposition process of glyphosate was studied by the DT and TG analysis. The results showed that the thermal decomposition temperature of glyphosate was above 198°C. And the decomposition process was divided into three stages: the zero stage is the decomposition of impurities, and the mass loss in the first and second stage may be methylene and carbonyl, respectively. It has been found that the ligand in the mentioned complexes is coordinated tridentivly via the nitrogen atom of amino group and oxygen atoms of the carbonyl and phosphate groups. The electronic spectrum of diffuse reflection of the cobalt (II) complex showed only one peak in the 534 nm region, corresponding to 4T1g (F)→ 4T1g (P) transition. This fact indicating the octahedral environment of the cobalt atom in complexes and causes its pink coloration. On the base of TGA and DTA analysis, IR spectroscopy and elemental analysis, the following compositions of the complexes were proposed: Na4CuL2, Na4CоL2 and ZnHL. Based on the literature data and our studies it was assumed that above structures contain fivemembered chelate rings with the amine, carboxylate, and phosphonate groups of the glyphosate ligand involved in chelation. Unlike 3d-metal complexes with carbacylamidophosphates, the phosphoryl group of glyphosate does not participate in coordination.

Kinetics of the thermal treatment of an iron-molybdenum catalyst

The samples of iron molybdate obtained by the mixing of the solutions of ammonium heptamolybdate and iron nitrate were studied by thermal analysis. The temperature ranges and kinetic parameters of dehydration processes, the decomposition of impurities, and a topochemical reaction between iron and molybdenum oxides were determined. Data on the concentrations of solid phase components as functions of the temperature and duration of heat treatment were acquired.

Thermal analysis of 5′-deoxy-5′-iodo-2′,3′-O-isopropylidene-5-fluorouridine

The melting temperature, melting enthalpy, and specific heat capacities (C p) of 5′-deoxy-5′-iodo-2′,3′-O-isopropylidene-5-fluorouridine (DIOIPF) were measured using DSC-60 Differential Scanning Calorimetry. The melting temperature and melting enthalpy were obtained to be 453.80 K and 33.22 J g−1, respectively. The relationship between the specific heat capacity and temperature was obtained to be C p/J g−1 K−1 = 2.0261 – 0.0096T + 2 × 10−5 T 2 at the temperature range from 320.15 to 430.15 K. The thermal decomposition process was studied by the TG–DTA analyzer. The results showed that the thermal decomposition temperature of DIOIPF was above 487.84 K, and the decomposition process can be divided into three stages: the first stage is the decomposition of impurities, the mass loss in the second stage may be the sublimation of iodine and thermal decomposition process of the side-group C4H2O2N2F, and the third stage may be the thermal decomposition process of both the groups –CH3 and –CH2OCH2–. The obtained thermodynamic basic data are helpful for exploiting new synthetic method, engineering design, and commercial process of DIOIPF.

Study on thermal decomposition and the non-isothermal decomposition kinetics of glyphosate

The thermal decomposition process and non-isothermal decomposition kinetic of glyphosate were studied by the Differential thermal analysis (DTA) and Thermogravimetric analysis (TGA). The results showed that the thermal decomposition temperature of glyphosate was above 198 °C. And the decomposition process was divided into three stages: The zero stage is the decomposition of impurities, and the mass loss in the first and second stage may be methylene and carbonyl, respectively. The mechanism function and kinetic parameters of non-isothermal decomposition of glyphosate were obtained from the analysis of DTA–TG curves by the methods of Kissinger, Flynn–Wall–Ozawa, Distributed activation energy model, Doyle and Satava-Sestak, respectively. In the first stage, the kinetic equation of glyphosate decomposition obtained showed that the decomposition reaction is a Valensi equation of which is two-dimensional diffusion, 2D. Its activation energy and pre-exponential factor were obtained to be 201.10 kJ mol−1 and 1.15 × 1019 s−1, respectively. In the second stage, the kinetic equation of glyphosate decomposition obtained showed that the decomposition reaction is a Avrami–Erofeev equation of which is nucleation and growth, and whose reaction order (n) is 4. Its activation energy and pre-exponential factor were obtained to be 251.11 kJ mol−1 and 1.48 × 1021 s−1, respectively. Moreover, the results of thermodynamical analysis showed that enthalpy change of ΔH≠, entropy change of ΔS≠ and the change of Gibbs free energy of ΔG≠ were, respectively, 196.80 kJ mol−1,107.03 J mol−1 K−1, and 141.77 kJ mol−1 in the first stage of the process of thermal decomposition; and 246.26 kJ mol−1,146.43 J mol−1 K−1, and 160.82 kJ mol−1 in the second stage.

Corrosion of transport pipelines for CO2–Effect of water ingress

Abstract Both field experience and lab data indicate that the corrosion rate of carbon steel in pure dense phase CO 2 is near zero if no free water is present. The question is whether this also applies when other contaminants like SO x , NO x , H 2 S and O 2 are present in moderate amounts. In a pipeline network with different types of CO 2 sources, the commingling of streams with various impurities can give a very complex mixture, and side reactions like oxidation and decomposition of impurities can be foreseen. An important issue is how the contaminants partition between the various phases during pressure reduction and when free water is present. The corrosion mechanisms under these conditions are not well understood, and it becomes more and more uncertain what will happen when the concentration of contaminants including water increases. The paper addresses these issues and discusses recent corrosion flow loops and autoclaves results obtained in an ongoing sub-sea CO 2 transmission pipeline project.

Properties of ZnO nanocrystals prepared by radiation method

Zinc oxide nanoparticles were prepared by irradiation of aqueous solutions containing zinc(II) ions, propan-2-ol, polyvinyl alcohol, and hydrogen peroxide. Zinc oxide was found in solid phase either directly after irradiation, or after additional heat treatment. Various physicochemical parameters, including scintillation properties of prepared materials, were studied. After decomposition of impurities and annealing of oxygen vacancies, the samples showed intensive emission in visible spectral range and well-shaped exciton luminescence at 390–400 nm. The best scintillating properties had zinc oxide prepared from aqueous solutions containing zinc formate as initial precursor and hydrogen peroxide. Size of the crystalline particles ranged from tens to hundreds nm, depending on type of irradiated solution and post-irradiation thermal treatment.

The purification of perfluorinated compounds for commercial use

Two procedures for the purification of perfluorinated compounds have been studied: the decomposition of impurities using concentrated alkali, and additional fluorination of products with elementary fluorine catalysed by fluorides of transition metals. Characteristics of purified products of several classes (perfluorinated alkanes, ethers and trialkylamines) have been presented. The problems of systematization of some classes of perfluoroorganic compounds—alkanes, ethers, tertiary amines, cyclic analogues based on their physicochemical properties have been discussed. The connection between the change of boiling points of perfluorinated compounds and the number of carbon atoms has been established and the corresponding empirical equation has been proposed. Questions of interchangeability of perfluorinated organic compounds of several classes, for use as dielectrics, have been discussed. The influence of admixtures of by-products on the dielectric properties of perfluorinated compounds has been considered.

Development of a High Temperature Isotopic Exchange Process for Recovering Tritium from Fusion Fuel Impurities

AbstractA High Temperature Isotopic Exchange (HITEX) process has been developed for processing of fusion fuel streams. The design has advantages over previous systems which have been based on catalytic oxidation or decomposition of impurities, since it eliminates the need for impurity oxidation and electrolysis of DTO, and does not rely on complicated catalytic decomposition reactions. A conceptual flowsheet of complete HITEX-based fuel processing system is described. Testing of the HITEX reactor is underway with deuterated impurities. Details of the experimental HITEX test loop are reported in this paper, and the test loop is compared to a HITEX design recently proposed for ITER (International Thermonuclear Experimental Reactor).

A high-temperature isotopic exchange process for recovering tritium from fusion fuel impurities

A High-Temperature Isotopic Exchange (HITEX) process has been developed for processing of fusion fuel streams. The design has advantages over previous systems which have been based on catalytic oxidation or decomposition of impurities, since it eliminates the need for impurity oxidation and electrolysis of DTO, and does not rely on complicated catalytic decomposition reactions. A conceptual flowsheet of a complete HITEX-based fuel processing system is described. Testing of the HITEX reactor is under way with deuterated impurities. Details of the experimental HITEX test loop are reported in this paper, and the test loop is compared to a HITEX design recently proposed for ITER.