Influence of moisture content on NO2 sorption ability of cedar wood

This study examined the influence of moisture content (MC) on NO2 sorption ability of cedar (Cryptomeria japonica) wood using the specimens with different MCs. Four MC conditions were applied, namely 0%, 8.6%, 12.7% and 16.5%, based on the differences of bonding condition of water molecule in the wood substances. As a result, the NO2 sorption volume increased drastically due to the presence of water, and as the MC increased, the NO2 sorption volume increased slightly. The NO generation volume and nitric acid concentration in the specimens were evaluated after an aeration test, and it was strongly indicated that the NO2 reacted with water in the specimen, and that the NO generation volume increased as the content of multilayer adsorbed water increased. The nitric acid seemed to be formed by the reaction between NO2 and water, and it was then held in the specimen. Based on the NO2 sorption volume calculated using the NO generation volume, it was shown that the NO2 sorption after 12-h aeration was caused mainly by the reaction between NO2 and water. Furthermore, the presence of both water and extractives contributed to the NO2 sorption in the initial period, and the presence of water contributed greatly to the NO2 sorption over the long term.

Processing Technogenic Raw Materials-Phosphorus Slags with the Production of Precipitated Nanosilica and Simultaneous Recovery of Valuable Components

The paper provides a flow sheet of the phosphorus slag processing to produce precipitated silica (white soot). The process conditions for opening phosphorus slag at the I stage of leaching have been selected: the nitric acid concentration is 3.5 mol/dm3; the ratio S:L = 1:3.5; the temperature is 60 oС; and the process duration is 1 hour. The parameters of the white soot production II stage have been determined: the HNO3 concentration is 6.5 mol/dm3; the ratio S:L = 1:3.5; the temperature is 50 oС; and the process duration is 1 hour. The temperature effect on the white soot structure and the specific surface have been established. At optimal process parameters, the white soot batches have been obtained with the main SiO2 component content of 88.2 and 90.5 %, and a specific surface of 170 and 182 m2/g, respectively. The through recovery of silicon into a commercial product is 98.0 % of its initial content in slag.

Extraction behavior of Pu(IV), Th(IV), and fission product elements with hexapropyl and hexabutyl phosphoramides

Hexapropyl phosphoramide (HPPA) and hexabutyl phosphoramide (HBPA) were examined for the macrolevel extraction and stripping of tetravalent metal ions such as Pu(IV) and Th(IV). The solvation number of Pu(IV) with both the phosphoramides were measured. The number of stages was evaluated for the quantitative extraction and stripping of Pu(IV) and Th(IV) in cross-current mode with 1.1 M phosphoramides in xylene from the nitric acid medium. The distribution ratios for the extraction of Th(IV) were measured with 1.1 M phosphoramides in xylene as a function of equilibrium aqueous phase Th(IV) and nitric acid concentration. In addition, distribution ratios for the extraction of fission product elements such as Zr, Tc, Ru, lanthanides (La, Pr, Nd and Gd) and activation product Am were also measured with 1.1 M HPPA and HBPA in n-Dodecane (n-DD) system as a function of aqueous phase nitric acid concentration. The extraction data generated with phosphoramides were compared with a 1.1 M TBP/n-DD system.

Making Oxalic Acid From Palm Oil Pelepah (Elaeis Guineensis) Through Nitric Acid Oxidation Reaction

Palm oil palm is one of the solid waste produced by oil palm plantations every harvest. Chemical analysis of palm oil palm oil pellets showed that there are components of cellulose, hemiscellulose, and lignin that show that palm oil pellets have the opportunity to be further processed into useful and economically valuable products. Palm waste contains cellulose by 34.89%, hemiscellulose by 27.14%, and lignin by 19.87%. The analysis conducted on raw materials includes the analysis of water content and cellulose levels of palm oil palm oil. 46.6% and cellulose levels of 29.2%. In this study quantitative analysis was conducted in the form of cellulose conversion and oxalic acid yield. The largest cellulose conversion was obtained at the use of 70% nitric acid concentration and 80 minutes reaction time of 58.56%.

ДОСЛІДЖЕННЯ ПРОЦЕСУ НІТРАТНОКИСЛОТНОЇ ПЕРЕРОБКИ ФОСФОГІПСУ З ОДЕРЖАННЯМ КОНЦЕНТРАТУ РІДКІСНОЗЕМЕЛЬНИХ ЕЛЕМЕНТІВ

Investigate the process of extraction of rare earth elements from phosphogypsum by its interaction with nitric acid, concentration 25, 30 and 35%, at a ratio of "phosphogypsum: acid" 1: 2 and a temperature of 700C to obtain purified calcium sulfate. Regularities of the process of extraction of concentrate of rare earth elements from phosphogypsum by acid leaching are obtained. Experimental studies were performed using the titrimetric method using Trilon B to determine the concentration of rare earth elements in the obtained filtrates. A review of scientific and technical literature in the field of promising methods of processing phosphogypsum. The most alternative method of processing phosphogypsum is to obtain rare earth elements by acid leaching, which is provided by the use of mineral acids. Based on the obtained data, it was found that when the acid concentration increases from 25 to 35%, the content of rare earth elements (REE) in the filtrates of the samples increases from 0.21 to 1.68 g/dm3, respectively. It was found that the degree of extraction of REE concentrate from phosphogypsum is highest at an acid concentration of 25% and is 22.8%, and with increasing concentration of HNO3, it decreases by almost 2.5 times. The optimal concentration of the nitric acid solution was determined, which is 25% and interacts with phosphogypsum for the subsequent extraction of the precipitate of rare earth elements.The optimal temperature of nitric acid processing of phosphogypsum, which is 70 0C, was revealed. Regularities of the process of extraction of concentrate of rare earth elements from phosphogypsum by acid leaching are obtained.The use of nitric acid for the production of rare earth elements from phosphogypsum and for the production of purified phosphogypsum sediment from soluble impurities scientifically substantiated. The content of rare earth elements in the filtrate was determined at various acid concentrations. The efficiency of sediment removal of rare earth elements from phosphogypsum by interaction with nitric acid at a concentration of 25, 30 and 35%, respectively, was established. Purified phosphogypsum can then be used to produce gypsum binder in the construction industry and in fertilizer technology in agriculture. Concentrate of rare earth elements can be used in medicine, metallurgy and other industries with the selection of individual elements and in general.

Development of a Simple and Fast Procedure Based on Acid Dilution for Determination of Macro and Microelements in Guarana-Based Beverages by ICP OES

A simple analytical procedure is proposed for the direct analysis of guarana-based beverages in order to determine nutrient elements by inductively coupled plasma optical emission spectrometry (ICP OES). A Box-Behnken design, combined with Derringer’s desirability function, was applied to the simultaneous optimization of the ICP OES radiofrequency (RF), sample volume and nitric acid concentration. Using this approach, optimal conditions were established as RF power of 1.40 kW, and 5.0 mL of sample diluted twice with 0.5 mol L-1 HNO3. The optimized procedure allowed the determination of Cu, Fe, Mn, Zn, K, Ca, S, P and Mg with limits of quantification of 10.0, 2.0, 0.6, 6.0, 66.0, 65.0, 235, 40.0 and 20.0 μg L-1, respectively. Accuracy of the method was evaluated through analysis of water standard reference material (SRM NIST 1643f) and by additionrecovery experiments, in which satisfactory recoveries were obtained. The procedure was applied for the analysis of guarana-based soft and energy drinks. The concentration ranges (mg L-1) were: 0.36‑43.3 (Ca), 4.04-192 (K), 0.36-44.8 (Mg), 10.1-1,073 (S), 0.04-92.4 (P), < 0.010-0.0174 (Cu), < 0.002-0.294 (Fe), < 0.006-0.06 (Zn) and < 0.0006-0.168 (Mn).

MODELING OF HYDROCHEMICAL OXIDATION OF HEAZLEWOODITE WITH NITRIC ACID

В работе представлены результаты математического моделирования окислительного растворения хизлевудита в растворах азотной кислоты в условиях равнодоступной поверхности вращающегося диска с применением метода полного факторного эксперимента. Получены и проанализированы зависимости скорости процесса гидрохимического окисления сульфида никеля (W, моль/смс) от продолжительности взаимодействия (τ, с), влияния концентрации азотной кислоты (С, моль/дм), частоты вращения диска (ω, с) и температуры (Т, К). Определены основные кинетические параметры: константа скорости и эффективная энергия активации процесса. Установлены режимы взаимодействия хизлевудита с азотной кислотой, выявлены вероятные лимитирующие стадии взаимодействия. The paper presents the results of mathematical modeling of the oxidative dissolution of hizlewudite in solutions of nitric acid using the rotating disk method and the factor experimental design. The dependences of specific speed of dissolution of sulfide of nickel Nickel sulfide (W, mol/cmc) on the duration of interaction (τ, s), the influence of nitric acid concentration (C, mol/dm), frequencies of rotation disk (ω, s) and temperatures (T, K) were obtained and analyzed. The main kinetic parameters are determined: the rate constant and the activation energy of the process. Established modes of interaction heazlewoodite with nitric acid, identified probable limiting stage of the interaction.

Studies on volatilization behavior of RuO4 from nitric acid medium

This paper reports volatilization behavior of RuO4 from nitric acid medium using UV–Vis spectroscopy. Ruthenium (III) solution was oxidized to Ru (VIII) using potassium metaperiodate. The absorption peak of RuO4 at 385 nm was used to measure Ru(VIII) concentration in solution. The volatilization kinetics has been studied at different temperature and used to derive rate constant and activation energy values. Almost 82% Ruthenium (VIII) has been volatilized from nitric acid medium at 70 °C whereas it is only 15% at 25 °C. Effect of different parameters like temperature, potassium metaperiodate concentration and nitric acid concentration on volatilization has been studied in depth and reported in this paper.

Interference of Zr(IV) during the extraction of trivalent Nd(III) from the aqueous waste generated from metallic fuel reprocessing

A metallic alloy of uranium–zirconium and uranium–plutonium–zirconium has been proposed as a fuel for fast reactors, owing to the possibility of achieving high breeding ratio in a short span of time. About 6–10 wt.% of zirconium has been added to these actinide fuels to increase the melting temperature and thermal-mechanical stability. Aqueous reprocessing of the spent metallic fuel generates the high-level liquid waste (HLLW) that contains about 60 % of the total zirconium from the fuel. In view of this, the extraction behavior of a trivalent representative ion, Nd(III) in the presence of Zr(IV) was studied from nitric acid medium using the candidate ligands proposed for trivalent actinide separation from HLLW, such as N,N,N′N′-tetraoctyldiglycolamide (TODGA), and N,N-di-octyl-2-hydroxyacetamide (DOHyA). The extraction was studied as a function of nitric acid concentration, zirconium and neodymium concentration and Nd(III) to Zr(IV) ratio. The findings of dynamic light scattering (DLS) and ATR-FTIR spectral techniques were used for understanding the complex chemistry of Zr(IV) extraction under different conditions. Poor extraction of nitric acid, smaller aggregate size, no third phase formation during the extraction of Zr(IV) and Nd(III) and other unique solvent properties favor the DOHyA molecule in n-dodecane as a solvent for partitioning of trivalent actinides from HLLW generated from metallic fuel reprocessing.