Development of NaNO2–O2 system as an oxidant at uranium leaching processes

A process of ferrous ion oxidation by sodium nitrite in sulfate uranium in situ leaching solutions was investigated. Kinetic, spectrophotometric, and heat effect studies have been made in order to investigate the chemistry of the oxidation process. As a result the method of ferrous ion oxidation in uranium in situ leaching solution was developed that makes possible to decrease sodium nitrite consumption by 20?C30 times comparing with traditional oxidation technique. It was founded also that process of ferrous ion oxidation can be conducted with partial sodium nitrite recirculation.     

Transport properties in the nanofiltration of NaNO3–water solutions with a weak acid polyelectrolyte membrane

The nanofiltration of 0.02–1.0 mol/dm³ NaNO₃ solutions at pH 4.0 and 8.0 using a dynamically-formed zirconium hydrous oxide-polyacrylate (FIP-ZPA) membrane has been investigated at 318 K. The practical transport coefficients for hydrodynamic permeability (L_p), reflection (σ) and solute permeability (ω), were calculated from the nanofiltration results using irreversible thermodynamic equations.     

HPLC荧光法快速检测食品中的NaNO2

建立了HPLC荧光检测法测定不同食品中的NaNO2。碱性条件下以乙酸锌作为蛋白质沉淀剂纯化提取NaNO2。以C8柱作为分析柱,反相C18柱作为预柱,流动相V(水)∶V(乙腈)=60∶40,荧光检测器在激发波长375 nm发射波长415 nm条件下检测,相关系数r=0.9999,方法检出限为0.01 mg/kg,回收率84.6%~103%,相对标准偏差1.0%~5.0%。方法可用于食品中NaNO2的检测。     

SELECTIVE AND EFFICIENT OXIDATION OF DIARYL CARBAZIDE TO DIARYL CARBAZONE WITH NaNO2–ACETIC ANHYDRIDE UNDER MILD CONDITIONS

ABSTRACT

In this paper, ten diaryl carbazide undergo selective and rapid oxidation to the corresponding diaryl carbazone using NaNO₂–acetic anhydride as a novel oxidant under mild conditions for the first time.     

Alumina–Methanesulfonic Acid (AMA)/NaNO2 as an Efficient Procedure for the Chemoselectivite N‐Nitrosation of Secondary Amines

A combination of alumina/methanesulfonic acid (AMA) and sodium nitrite was used as an effective nitrosating agent for the nitrosation of secondary amines under mild and heterogeneous conditions in good to excellent yields.     

在NaNO3存在下浮选CuSCN间接测定抗坏血酸

建立了浮选CuSCN间接测定抗坏血酸(Vc)的方法。研究表明,在NaNO3存在下,Cu(Ⅱ)被抗坏血酸还原生成的Cu(Ⅰ)与SCN-形成CuSCN沉淀而被浮选。结果表明,Vc量在2.64~15.8 mg/L范围内与CuSCN的浮选率呈良好的线性关系,回归方程为:E/%=6.008ρ-3.673,r=0.9962。此方法可用于水果和药片中Vc量测定。     

Thermodynamic Model for the Solubility of Cr(OH)3(am) in Concentrated NaOH and NaOH–NaNO3 Solutions

The main objective of this study was to develop a thermodynamic model for predicting Cr(III) behavior in concentrated NaOH and in mixed NaOH–NaNO₃ solutions for application to developing effective caustic leaching strategies for high-level nuclear waste sludges. To meet this objective, the solubility of Cr(OH)₃(am) was measured in 0.003 to 10.5 m NaOH, 3.0 m NaOH with NaNO₃ varying from 0.1 to 7.5 m, and 4.6 m NaNO₃ with NaOH varying from 0.1 to 3.5 m at room temperature (22 ± 2°C). A combination of techniques, X-ray absorption spectroscopy (XAS) and absorptive stripping voltammetry analyses, were used to determine the oxidation state and nature of aqueous Cr. A thermodynamic model, based on the Pitzer equations, was developed from the solubility measurements to account for dramatic increases in aqueous Cr with increases in NaOH concentration. The model includes only two aqueous Cr species, Cr(OH) ₄ ^– and Cr₂O₂(OH) ₄ ^– (although the possible presence of a small percentage of higher oligomers at >5.0 m NaOH cannot be discounted) and their ion–interaction parameters with Na⁺. The logarithms of the equilibrium constants for the reactions involving Cr(OH) ₄ ^– [Cr(OH)₃(am) + OH^– Cr(OH) ₄ ^– ] and Cr₂O₂(OH) ₄ ^2– [2Cr(OH)₃(am) + 2OH^– Cr₂O₂(OH) ₄ ^2– + 2H₂O] were determined to be –4.36 ± 0.24 and –5.24 ± 0.24, respectively. This model was further tested and provided close agreement between the observed Cr concentrations in equilibrium with Cr(OH)₃(am) in mixed NaOH–NaNO₃ solutions and with high-level tank sludges leached with and primarily containing NaOH as the major electrolyte.     

Crystal structure of (glycine) sodium nitrate Gly·NaNO3

The crystal structure of Gly·NaNO₃ was determined by single crystal diffraction methods (monoclinic crystal system, B11n, a = 14.339(3) Å, b = 9.136(3) Å, c = 5.263(3) Å, γ = 119.14(5)°). The structure is built from alternating layers of glycine organic molecules and inorganic layers consisting of Na⁺ ions and planar NO ₃ ^? ions stretching along the b axis. The surroundings of the Na atom include the oxygen atoms of the NO ₃ ^? groups and the oxygen atoms of glycine molecules. The structure has a system of hydrogen bonds.     

NaNO3掺杂Y2O3材料的制备及电流变性质

利用NaCO3和Y（NO3）3做主要原料，合成了一系列用稀土氧化物（Y2O3）作为基础材料的新型电流变材料——NaNO3掺杂Y2O3材料。对于这些材料的介电性质、微观结构和电流变性能的研究结果表明，NaNO3的掺杂可以明显地提高Y2O3材料的电流变活性。材料在二甲基硅油中的悬浮液的剪切应力随NaNO3在Y2O3中的掺杂程度有明显变化，当Na／Y（物质的量的比）为0．6时材料的电流变性能最好，     

NaNO3和NaClO4在N,N-二甲基甲酰胺中的离子溶剂化

利用红外光谱研究了NaNO₃和NaClO₄在N,N-二甲基甲酰胺(DMF)溶剂中发生离子-溶剂和离子-离子的相互作用, 分析结果表明, DMF的OC-N谱带发生了明显的变化. 定量计算了在Na⁺浓度为0.22~1.24 mol/kg范围内的溶剂化数为1~4. 对谱图中酰胺基上C-N和CO的特征峰强度随Na⁺浓度变化的对比, 推测离子溶剂化作用导致DMF的酰胺基内部形成共轭键. 利用量子化学方法进行优化及热力学性质计算, 得到C-N键伸缩振动频率及红外光谱强度变化规律. 优化结构与实验结论相符合. 由NaNO₃的ν₂谱带及NaClO₄的ν₁谱带的解析得到溶液中阴离子缔合效应的一般规律, 并通过阴离子缔合特征峰与酰胺基上的N-C-N面外振动峰(865 cm^-1)的变化情况, 讨论了溶液中的离子溶剂化作用.     

非过渡金属催化体系NHPI/DDQ/NaNO2催化分子氧选择氧化醇

考察了N-羟基邻苯二甲酰亚胺(NHPI),2,3-二氯-5,6-二氰基-1,4-苯醌(DDQ)与NaNO2组成的非金属催化体系,催化分子氧选择氧化醇的反应性能.结果表明,该体系可有效地催化芳香醇等生成相应的醛(酮).在80℃反应6h,苯甲醇转化率达到65%,苯甲醛选择性为99%.此外,该催化体系也能有效地催化其它醇的选...     

2,3-二氯-5,6-二氰基-1,4-苯醌/NaNO2

设计了一种由 2,3-二氯-5,6-二氰基-1,4-苯醌(DDQ)和NaNO2组成的复合催化剂,该催化剂在9,10-二氢蒽氧化脱氢生成蒽的反应中表现出很高的催化活性和选择性. 在120 ℃和1.3 MPa O2下反应 8 h, 9,10-二氢蒽转化率达到99%以上,蒽的选择性为99%. 采用红外光谱和核磁共振方法对催化氧化脱氢的反应历程进行了研究. 结果表明, 9,10-二氢蒽氧气氧化脱氢生成蒽的反应是通过DDQ/DDQH2和NO2/NO两个氧化还原对的电子传递来推动的,以DDQ/NaNO2为催化剂可以有效催化9,10-二氢蒽氧化脱氢生成蒽.     

甘氨酸和L-丝氨酸在LiNO3,NaNO3和KNO3水溶液中的体积性质

用Anton Paar DMA 55精密数字密度计测定了甘氨酸和L-丝氨酸在LiNO3, NaNO3和KNO3水溶液中的密度, 计算了氨基酸的表观摩尔体积、极限偏摩尔体积、迁移偏摩尔体积、理论水化数和体积作用系数. 根据静电相互作用和结构水合作用模型讨论了氨基酸的侧链和阳离子的性质对迁移偏摩尔体积的影响. 结果表明, 甘氨酸和L-丝氨酸在3种硝酸盐水溶液中的迁移体积均为正值, 并且随着盐溶液浓度的增大而增大. 氨基酸两性离子端基和阴阳离子间的静电作用对迁移体积的贡献是主要的, 静电作用削弱了两性离子带电中心对周围水分子的电致收缩效应, 造成氨基酸的理论水化数随盐溶液浓度的增加而减小. L-丝氨酸的侧链与离子之间的亲水-亲水相互作用对迁移体积有小的正贡献, 使得在同一种盐溶液中L-丝氨酸的迁移体积较甘氨酸的大. 同一种氨基酸在NaNO3和KNO3水溶液中的迁移体积较在LiNO3水溶液中的大, 主要是由于Li＋难以去水化. 在低浓度的盐溶液中氨基酸与盐之间的相互作用以1∶1形式为主, 随着溶液浓度的增大, 1∶2形式的相互作用逐渐增大     

Nitration Reaction Catalyzed by Horseradish Peroxidase in the Presence of H2O2 and NaNO2

The enzymatic nitration of phenol and m-cresol catalyzed by horseradish peroxidase was studied in the presence of H2O2 and NaNO2. The results showed that the nitration products of phenol were 2-nitro and 4-nitrophenols. There was also a small amount of by-products of hydroquinone and catechol. The influences of various reaction parameters, including pH, organic solvent type, and concentrations of NaNO2 and H2O2, on the nitration products were investigated. The yields of 4-nitrophenol and 2-nitrophenol were 14% and 12%, respectively. The nitration products of m-cresol were 4-nitro-m-cresol and 6-nitro-m-cresol, and the yields of 4-nitro-m-cresol and 6-nitro-m-cresol were 19% and 30%, respectively.     

Electrochemical reactivity of Li–Mn–O and Li–Fe–Mn–O spinels

Electrochemical reductive dissolution of Li–Mn–O and Li–Fe–Mn–O spinels and Li⁺ extraction/insertion in these oxides were performed using voltammetry of microparticles. Both electrochemical reactions are sensitive to the Fe/(Fe+Mn) ratio, specific surface area, Li content in tetrahedral positions, and Mn valence, and can be used for electrochemical analysis of the homogeneity of the elemental and phase composition of synthetic samples. The peak potential (E _P) of the reductive dissolution of the Li–Mn–O spinel is directly proportional to the logarithm of the specific surface area. E _P of Li–Fe–Mn–O spinels is mainly controlled by the Fe/(Fe+Mn) ratio. Li⁺ insertion/extraction can be performed with Mn-rich Li–Fe–Mn–O spinels in aqueous solution under an ambient atmosphere and it is sensitive to the regularity of the spinel structure, in particularly to the amount of Li in tetrahedral positions and the Mn valence. Electronic Publication     

Bubble points of hydrogen chloride–water–isopropanol and hydrogen chloride–water–isopropanol–benzene systems and liquid–liquid equilibria of hydrogen chloride–water–benzene and hydrogen chloride–water–isopropanol–benzene systems

Bubble points of the HCl–water–isopropanol and the HCl–water–isopropanol–benzene systems and liquid–liquid equilibria (LLE) of the HCl–water–benzene and the HCl–water– isopropanol–benzene systems were measured at 25–85°C and 30–70°C, respectively. The electrolyte nonrandom two-liquid model proposed by Chen et al. [C.-C. Chen, H.I. Britt, J.F. Boston, L.B. Evans, AIChE J. 28 (1982) 588–596] can satisfactorily correlate bubble points and liquid–liquid equilibria of the present mixed-solvent electrolyte systems over the entire range of temperature and concentrations using only binary adjustable parameters.     

On hydrolysis of Ba–Bi–O and K–Ba–Bi–O oxide systems

Fundamentally different behavior of Ba–Bi–O (Ba : Bi = 11 : 4, 1 : 1, 2: 3, and 1 : 5 mol/mol) and K_nBa_mBi_m+nO_y (m = n = 1, 2,...; exhibiting superconducting properties with T_c = 28–32 K) oxides and BaO₂ in hydrolysis reactions has been revealed by means of potentiometry and chemical analysis. Products of the oxides treatment with water do not contain H₂O₂, evidencing the absence of peroxide ions in their structure. The perovskite-type barium-bismuth(III) oxides are completely hydrolyzed into Ba(OH)₂ and Bi₂O₃ at room temperature.     

New Phase in the Bi–Sr–Ca–Cu–O System

Cooling a melt of a Bi–Sr–Ca–Cu–O system (Bi:Sr:Ca:Cu = 4:3:3:4 or 2:2:2:4) from 1000°C-1050°C yielded crystals of a new red-colored nonsuperconducting phase, accompanying the superconducting 2212 and 2201 phases. Based on the EPR spectra, it was concluded that copper is univalent in this compound. The new phase has a composition Bi_2.2Sr_1.6Ca_1.3Cu₂Ox. The X-ray diffraction pattern has been indexed, and the unit cell parameters of the phase have been determined: space group P2/m, a = 12.93, b = 4.55, c = 10.94 ; = 102.72°.     

BTATz–HNIW–CMDB propellants

The high nitrogen compound 3,6-bis(1H-1,2,3,4-tetrazol-5-yl-amino)-1,2,4,5-tetrazine and the high energy density material hexanitrohexaazaisowurtzitane (HNIW), were used as substitute of hexogen (RDX) in the composite modified double base (CMDB) propellant formulations, the propellant samples were prepared, the thermal behaviors, nonisothermal reaction kinetics, and thermal safety were carried out, and the eight important parameters were calculated and obtained as the self-accelerating decomposition temperature (T _SADT), thermal ignition temperature (T _TIT), critical temperatures of thermal explosion (T _b), critical temperature of hot-spot initiation (T _cr,hot-spot), characteristic drop height of impact sensitivity (H ₅₀), critical thermal explosion ambient temperature (T _acr), safety degree (S _d), and thermal explosion probability (P _TE). It shows that the content of HNIW has a large effect on the decomposition reaction mechanism of the CMDB propellant, when the content of HNIW is 10 %, the decomposition reaction are controlled by the random nucleation and subsequent growth (n = l), and the reaction mechanism obeys Mampel law; but when the content of HNIW is 20 %, the decomposition reaction are controlled by the chemical reaction (n = 1/4). The mechanism can not be changed by the catalysts, and they just make the apparent activation energy change slightly. For the sample, from BC01 to BC04, the values of T _SADT and T _TIT making an upward tendency, show the resistivity to heat: BC04 > BC03 > BC02 > BC01; the values of T _acr and S _d, BC01 are the maximum and BC02 are the minimum, show the heat sensitivity: BC01 > BC03 > BC04 > BC02. For the same radius, the thermal safety of the sphere sample is greater than that of the infinite cylinder one.     

Metal-Free–Catalyzed Oxidative Trimerization of Indoles Using NaNO2 to Construct Quaternary Carbon Centers: Synthesis of 2-(1H-Indol-3-yl)-2,3′-biindolin-3-ones

A simple, convenient, and efficient synthesis of 2-(1H-indol-3-yl)-2,3′-biindolin-3-one derivatives via a transition-metal-free-catalyzed oxidative trimeric reaction of indoles has been developed. This transformation may have occurred through a tandem oxidative homocoupling reaction by using NaNO₂ in pyridine as oxidant. This methodology provides an alternative approach for the direct generation of all-carbon quaternary centers at the C2 position of indoles.